I2–DMSO–PTSA a simple and metal free oxidative cross coupling of imidazo[1,2-a]pyridines

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A_review_of_advanced_and_practical_lithium_battery_materials

A review of advanced and practical lithium battery materialsRotem Marom,*S.Francis Amalraj,Nicole Leifer,David Jacob and Doron AurbachReceived 3rd December 2010,Accepted 31st January 2011DOI:10.1039/c0jm04225kPresented herein is a discussion of the forefront in research and development of advanced electrode materials and electrolyte solutions for the next generation of lithium ion batteries.The main challenge of the ﬁeld today is in meeting the demands necessary to make the electric vehicle fully commercially viable.This requires high energy and power densities with no compromise in safety.Three families of advanced cathode materials (the limiting factor for energy density in the Li battery systems)are discussed in detail:LiMn 1.5Ni 0.5O 4high voltage spinel compounds,Li 2MnO 3–LiMO 2high capacity composite layered compounds,and LiMPO 4,where M ¼Fe,Mn.Graphite,Si,Li x TO y ,and MO (conversion reactions)are discussed as anode materials.The electrolyte is a key component that determines the ability to use high voltage cathodes and low voltage anodes in the same system.Electrode–solution interactions and passivation phenomena on both electrodes in Li-ion batteries also play signiﬁcant roles in determining stability,cycle life and safety features.This presentation is aimed at providing an overall picture of the road map necessary for the future development of advanced high energy density Li-ion batteries for EV applications.IntroductionOne of the greatest challenges of modern society is to stabilize a consistent energy supply that will meet our growing energy demands.A consideration of the facts at hand related to the energy sources on earth reveals that we are not encountering an energy crisis related to a shortage in total resources.For instancethe earth’s crust contains enough coal for the production of electricity for hundreds of years.1However the continued unbridled usage of this resource as it is currently employed may potentially bring about catastrophic climatological effects.As far as the availability of crude oil,however,it in fact appears that we are already beyond ‘peak’production.2As a result,increasing oil shortages in the near future seem inevitable.Therefore it is of critical importance to considerably decrease our use of oil for propulsion by developing effective electric vehicles (EVs).EV applications require high energy density energy storage devices that can enable a reasonable driving range betweenDepartment of Chemistry,Bar-Ilan University,Ramat-Gan,52900,Israel;Web:http://www.ch.biu.ac.il/people/aurbach.E-mail:rotem.marom@live.biu.ac.il;aurbach@mail.biu.ac.ilRotem MaromRotem Marom received her BS degree in organic chemistry (2005)and MS degree in poly-mer chemistry (2007)from Bar-Ilan University,Ramat Gan,Israel.She started a PhD in electrochemistry under the supervision of Prof.D.Aurbach in 2010.She is currently con-ducting research on a variety of lithium ion battery materials for electric vehicles,with a focus on electrolyte solutions,salts andadditives.S :Francis AmalrajFrancis Amalraj hails from Tamil Nadu,India.He received his MSc in Applied Chemistry from Anna University.He then carried out his doctoral studies at National Chemical Laboratory,Pune and obtained his PhD in Chemistry from Pune University (2008).He is currently a postdoctoral fellow in Prof.Doron Aurbach’s group at Bar-Ilan University,Israel.His current research interest focuses on the synthesis,electrochemical and transport properties of high ener-getic electrode materials for energy conversion and storage systems.Dynamic Article Links CJournal ofMaterials ChemistryCite this:DOI:10.1039/c0jm04225k /materialsFEATURE ARTICLED o w n l o a d e d b y B e i j i n g U n i v e r s i t y o f C h e m i c a l T e c h n o l o g y o n 24 F e b r u a r y 2011P u b l i s h e d o n 23 F e b r u a r y 2011 o n h t t p ://p u b s .r s c .o r g | d o i :10.1039/C 0J M 04225KView Onlinecharges and maintain acceptable speeds.3Other important requirements are high power density and acceptable safety features.The energy storage ﬁeld faces a second critical chal-lenge:namely,the development of rechargeable systems for load leveling applications (e.g.storing solar and wind energy,and reducing the massive wasted electricity from conventional fossil fuel combustion plants).4Here the main requirements are a very prolonged cycle life,components (i.e.,relevant elements)abun-dant in high quantities in the earth’s crust,and environmentally friendly systems.Since it is not clear whether Li-ion battery technology can contribute signiﬁcantly to this application,battery-centered solutions for this application are not discussedherein.In fact,even for electrical propulsion,the non-petroleum power source with the highest energy density is the H 2/O 2fuel cell (FC).5However,despite impressive developments in recent years in the ﬁeld,there are intrinsic problems related to electrocatalysis in the FCs and the storage of hydrogen 6that will need many years of R&D to solve.Hence,for the foreseeable future,rechargeable batteries appear to be the most practically viable power source for EVs.Among the available battery technologies to date,only Li-ion batteries may possess the power and energy densities necessary for EV applications.The commonly used Li-ion batteries that power almost all portable electronic equipment today are comprised of a graphite anode and a LiCoO 2cathode (3.6V system)and can reach a practical energy density of 150W h kg À1in single cells.This battery technology is not very useful for EV application due to its limited cycle life (especially at elevated temperatures)and prob-lematic safety features (especially for large,multi-cell modules).7While there are ongoing developments in the hybrid EV ﬁeld,including practical ones in which only part of the propulsion of the car is driven by an electrical motor and batteries,8the main goal of the battery community is to be able to develop full EV applications.This necessitates the development of Li-ion batteries with much higher energy densities compared to the practical state-of-the-art.The biggest challenge is that Li-ion batteries are complicated devices whose components never reach thermodynamic stability.The surface chemistry that occurs within these systems is very complicated,as described brieﬂy below,and continues to be the main factor that determines their performance.9Nicole Leifer Nicole Leifer received a BS degree in chemistry from MIT in 1998.After teaching high school chemistry and physics for several years at Stuyvesant High School in New York City,she began work towards her PhD in solid state physics from the City University of New York Grad-uate Center.Her research con-sisted primarily of employing solid state NMR in the study of lithium ion electrode materialsand electrode surfacephenomena with Prof.Green-baum at Hunter College andProf.Grey at Stony Brook University.After completing her PhD she joined Prof.Doron Aurbach for a postdoctorate at Bar-Ilan University to continue work in lithium ion battery research.There she continues her work in using NMR to study lithium materials in addition to new forays into carbon materials’research for super-capacitor applications with a focus on enhancement of electro-chemical performance through the incorporation of carbonnanotubes.David Jacob David Jacob earned a BSc from Amravati University in 1998,an MSc from Pune University in 2000,and completed his PhD at Bar-Ilan University in 2007under the tutelage of Professor Aharon Gedanken.As part of his PhD research,he developed novel methods of synthesizing metal ﬂuoride nano-material structures in ionic liquids.Upon ﬁnishing his PhD he joined Prof.Doron Aurbach’s lithium ionbattery group at Bar-Ilan in2007as a post-doctorate and during that time developed newformulations of electrolyte solutions for Li-ion batteries.He has a great interest in nanotechnology and as of 2011,has become the CEO of IsraZion Ltd.,a company dedicated to the manufacturing of novelnano-materials.Doron Aurbach Dr Doron Aurbach is a full Professor in the Department of Chemistry at Bar-Ilan Univer-sity (BIU)in Ramat Gan,Israel and a senate member at BIU since 1996.He chaired the chemistry department there during the years 2001–2005.He is also the chairman of the Israeli Labs Accreditation Authority.He founded the elec-trochemistry group at BIU at the end of 1985.His groupconducts research in thefollowing ﬁelds:Li ion batteries for electric vehicles and for otherportable uses (new cathodes,anodes,electrolyte solutions,elec-trodes–solution interactions,practical systems),rechargeable magnesium batteries,electronically conducting polymers,super-capacitors,engineering of new carbonaceous materials,develop-ment of devices for storage and conversion of sustainable energy (solar,wind)sensors and water desalination.The group currently collaborates with several prominent research groups in Europe and the US and with several commercial companies in Israel and abroad.He is also a fellow of the ECS and ISE as well as an associate editor of Electrochemical and Solid State Letters and the Journal of Solid State Electrochemistry.Prof.Aurbach has more than 350journals publications.D o w n l o a d e d b y B e i j i n g U n i v e r s i t y o f C h e m i c a l T e c h n o l o g y o n 24 F e b r u a r y 2011P u b l i s h e d o n 23 F e b r u a r y 2011 o n h t t p ://p u b s .r s c .o r g | d o i :10.1039/C 0J M 04225KAll electrodes,excluding 1.5V systems such as LiTiO x anodes,are surface-ﬁlm controlled (SFC)systems.At the anode side,all conventional electrolyte systems can be reduced in the presence of Li ions below 1.5V,thus forming insoluble Li-ion salts that comprise a passivating surface layer of particles referred to as the solid electrolyte interphase (SEI).10The cathode side is less trivial.Alkyl carbonates can be oxidized at potentials below 4V.11These reactions are inhibited on the passivated aluminium current collectors (Al CC)and on the composite cathodes.There is a rich surface chemistry on the cathode surface as well.In their lithiated state,nucleophilic oxygen anions in the surface layer of the cathode particles attack electrophilic RO(CO)OR solvents,forming different combinations of surface components (e.g.ROCO 2Li,ROCO 2M,ROLi,ROM etc.)depending on the electrolytes used.12The polymerization of solvent molecules such as EC by cationic stimulation results in the formation of poly-carbonates.13The dissolution of transition metal cations forms surface inactive Li x MO y phases.14Their precipitation on the anode side destroys the passivation of the negative electrodes.15Red-ox reactions with solution species form inactive LiMO y with the transition metal M at a lower oxidation state.14LiMO y compounds are spontaneously delithiated in air due to reactions with CO 2.16Acid–base reactions occur in the LiPF 6solutions (trace HF,water)that are commonly used in Li-ion batteries.Finally,LiCoO 2itself has a rich surface chemistry that inﬂuences its performance:4LiCo III O 2 !Co IV O 2þCo II Co III 2O 4þ2Li 2O !4HF4LiF þ2H 2O Co III compounds oxidize alkyl carbonates;CO 2is one of the products,Co III /Co II /Co 2+dissolution.14Interestingly,this process seems to be self-limiting,as the presence of Co 2+ions in solution itself stabilizes the LiCoO 2electrodes,17However,Co metal in turn appears to deposit on the negative electrodes,destroying their passivation.Hence the performance of many types of electrodes depends on their surface chemistry.Unfortunately surface studies provide more ambiguous results than bulk studies,therefore there are still many open questions related to the surface chemistry of Li-ion battery systems.It is for these reasons that proper R&D of advanced materials for Li-ion batteries has to include bulk structural and perfor-mance studies,electrode–solution interactions,and possible reﬂections between the anode and cathode.These studies require the use of the most advanced electrochemical,18structural (XRD,HR microscopy),spectroscopic and surface sensitive analytical techniques (SS NMR,19FTIR,20XPS,21Raman,22X-ray based spectroscopies 23).This presentation provides a review of the forefront of the study of advanced materials—electrolyte systems,current collectors,anode materials,and ﬁnally advanced cathodes materials used in Li-ion batteries,with the emphasis on contributions from the authors’group.ExperimentalMany of the materials reviewed were studied in this laboratory,therefore the experimental details have been provided as follows.The LiMO 2compounds studied were prepared via self-combus-tion reactions (SCRs).24Li[MnNiCo]O 2and Li 2MnO 3$Li/MnNiCo]O 2materials were produced in nano-andsubmicrometric particles both produced by SCR with different annealing stages (700 C for 1hour in air,900 C or 1000 C for 22hours in air,respectively).LiMn 1.5Ni 0.5O 4spinel particles were also synthesized using SCR.Li 4T 5O 12nanoparticles were obtained from NEI Inc.,USA.Graphitic material was obtained from Superior Graphite (USA),Timcal (Switzerland),and Conoco-Philips.LiMn 0.8Fe 0.2PO 4was obtained from HPL Switzerland.Standard electrolyte solutions (alkyl carbonates/LiPF 6),ready to use,were obtained from UBE,Japan.Ionic liquids were obtained from Merck KGaA (Germany and Toyo Gosie Ltd.,(Japan)).The surface chemistry of the various electrodes was charac-terized by the following techniques:Fourier transform infrared (FTIR)spectroscopy using a Magna 860Spectrometer from Nicolet Inc.,placed in a homemade glove box purged with H 2O and CO 2(Balson Inc.air puriﬁcation system)and carried out in diffuse reﬂectance mode;high-resolution transmission electron microscopy (HR-TEM)and scanning electron microscopy (SEM),using a JEOL-JEM-2011(200kV)and JEOL-JSM-7000F electron microscopes,respectively,both equipped with an energy dispersive X-ray microanalysis system from Oxford Inc.;X-ray photoelectron spectroscopy (XPS)using an HX Axis spectrom-eter from Kratos,Inc.(England)with monochromic Al K a (1486.6eV)X-ray beam radiation;solid state 7Li magic angle spinning (MAS)NMR performed at 194.34MHz on a Bruker Avance 500MHz spectrometer in 3.2mm rotors at spinning speeds of 18–22kHz;single pulse and rotor synchronized Hahn echo sequences were used,and the spectra were referenced to 1M LiCl at 0ppm;MicroRaman spectroscopy with a spectrometerfrom Jobin-Yvon Inc.,France.We also used M €ossbauer spec-troscopy for studying the stability of LiMPO 4compounds (conventional constant-acceleration spectrometer,room temperature,50mC:57Co:Rh source,the absorbers were put in Perspex holders.In situ AFM measurements were carried out using the system described in ref.25.The following electrochemical measurements were posite electrodes were prepared by spreading slurries comprising the active mass,carbon powder and poly-vinylidene diﬂuoride (PVdF)binder (ratio of 75%:15%:10%by weight,mixed into N -methyl pyrrolidone (NMP),and deposited onto aluminium foil current collectors,followed by drying in a vacuum oven.The average load was around 2.5mg active mass per cm 2.These electrodes were tested in two-electrode,coin-type cells (Model 2032from NRC Canada)with Li foil serving as the counter electrode,and various electrolyte puter-ized multi-channel battery analyzers from Maccor Inc.(USA)and Arbin Inc.were used for galvanostatic measurements (voltage vs.time/capacity,measured at constant currents).Results and discussionOur road map for materials developmentFig.1indicates a suggested road map for the direction of Li-ion research.The axes are voltage and capacity,and a variety of electrode materials are marked therein according to their respective values.As is clear,the main limiting factor is the cathode material (in voltage and capacity).The electrode mate-rials currently used in today’s practical batteries allow forD o w n l o a d e d b y B e i j i n g U n i v e r s i t y o f C h e m i c a l T e c h n o l o g y o n 24 F e b r u a r y 2011P u b l i s h e d o n 23 F e b r u a r y 2011 o n h t t p ://p u b s .r s c .o r g | d o i :10.1039/C 0J M 04225Ka nominal voltage of below 4V.The lower limit of the electro-chemical window of the currently used electrolyte solutions (alkyl carbonates/LiPF 6)is approximately 1.5V vs.Li 26(see later discussion about the passivation phenomena that allow for the operation of lower voltage electrodes,such as Li and Li–graphite).The anodic limit of the electrochemical window of the alkyl carbonate/LiPF 6solutions has not been speciﬁcally determined but practical accepted values are between 4.2and 5V vs.Li 26(see further discussion).With some systems which will be discussed later,meta-stability up to 4.9V can be achieved in these standard electrolyte solutions.Electrolyte solutionsThe anodic stability limits of electrolyte solutions for Li-ion batteries (and those of polar aprotic solutions in general)demand ongoing research in this subﬁeld as well.It is hard to deﬁne the onset of oxidation reactions of nonaqueous electrolyte solutions because these strongly depend on the level of purity,the presence of contaminants,and the types of electrodes used.Alkyl carbonates are still the solutions of choice with little competition (except by ionic liquids,as discussed below)because of the high oxidation state of their central carbon (+4).Within this class of compounds EC and DMC have the highest anodic stability,due to their small alkyl groups.An additional beneﬁt is that,as discussed above,all kinds of negative electrodes,Li,Li–graphite,Li–Si,etc.,develop excellent passivation in these solutions at low potentials.The potentiodynamic behavior of polar aprotic solutions based on alkyl carbonates and inert electrodes (Pt,glassy carbon,Au)shows an impressive anodic stability and an irreversible cathodic wave whose onset is $1.5vs.Li,which does not appear in consequent cycles due to passivation of the anode surface bythe SEI.The onset of these oxidation reactions is not well deﬁned (>4/5V vs.Li).An important discovery was the fact that in the presence of Li salts,EC,one of the most reactive alkyl carbonates (in terms of reduction),forms a variety of semi-organic Li-con-taining salts that serve as passivation agents on Li,Li–carbon,Li–Si,and inert metal electrodes polarized to low potentials.Fig.2and Scheme 1indicates the most signiﬁcant reduction schemes for EC,as elucidated through spectroscopic measure-ments (FTIR,XPS,NMR,Raman).27–29It is important to note (as reﬂected in Scheme 1)that the nature of the Li salts present greatly affects the electrode surface chemistry.When the pres-ence of the salt does not induce the formation of acidic species in solutions (e.g.,LiClO 4,LiN(SO 2CF 3)2),alkyl carbonates are reduced to ROCO 2Li and ROLi compounds,as presented in Fig. 2.In LiPF 6solutions acidic species are formed:LiPF 6decomposes thermally to LiF and PF 5.The latter moiety is a Lewis acid which further reacts with any protic contaminants (e.g.unavoidably present traces of water)to form HF.The presence of such acidic species in solution strongly affects the surface chemistry in two ways.One way is that PF 5interactswithFig.1The road map for R&D of new electrode materials,compared to today’s state-of-the-art.The y and x axes are voltage and speciﬁc capacity,respectively.Fig.2A schematic presentation of the CV behavior of inert (Pt)elec-trodes in various families of polar aprotic solvents with Li salts.26D o w n l o a d e d b y B e i j i n g U n i v e r s i t y o f C h e m i c a l T e c h n o l o g y o n 24 F e b r u a r y 2011P u b l i s h e d o n 23 F e b r u a r y 2011 o n h t t p ://p u b s .r s c .o r g | d o i :10.1039/C 0J M 04225Kthe carbonyl group and channels the reduction process of EC to form ethylene di-alkoxide species along with more complicated alkoxy compounds such as binary and tertiary ethers,rather than Li-ethylene dicarbonates (see schemes in Fig.2);the other way is that HF reacts with ROLi and ROCO 2Li to form ROH,ROCO 2H (which further decomposes to ROH and CO 2),and surface LiF.Other species formed from the reduction of EC are Li-oxalate and moieties with Li–C and C–F bonds (see Scheme 1).27–31Efforts have been made to enhance the formation of the passivation layer (on graphite electrodes in particular)in the presence of these solutions through the use of surface-active additives such as vinylene carbonate (VC)and lithium bi-oxalato borate (LiBOB).27At this point there are hundreds of publica-tions and patents on various passivating agents,particularly for graphite electrodes;their further discussion is beyond the scope of this paper.Readers may instead be referred to the excellent review by Xu 32on this subject.Ionic liquids (ILs)have excellent qualities that could render them very relevant for use in advanced Li-ion batteries,including high anodic stability,low volatility and low ﬂammability.Their main drawbacks are their high viscosities,problems in wetting particle pores in composite structures,and low ionic conductivity at low temperatures.Recent years have seen increasing efforts to test ILs as solvents or additives in Li-ion battery systems.33Fig.3shows the cyclic voltammetric response (Pt working electrodes)of imidazolium-,piperidinium-,and pyrrolidinium-based ILs with N(SO 2CF 3)2Àanions containing LiN(SO 2CF 3)2salt.34This ﬁgure reﬂects the very wide electrochemical window and impressive anodic stability (>5V)of piperidium-and pyr-rolidium-based ILs.Imidazolium-based IL solutions have a much lower cathodic stability than the above cyclic quaternary ammonium cation-based IL solutions,as demonstrated in Fig.3.The cyclic voltammograms of several common electrode mate-rials measured in IL-based solutions are also included in the ﬁgure.It is clearly demonstrated that the Li,Li–Si,LiCoO 2,andLiMn 1.5Ni 0.5O 4electrodes behave reversibly in piperidium-and pyrrolidium-based ILs with N(SO 2CF 3)2Àand LiN(SO 2CF 3)2salts.This ﬁgure demonstrates the main advantage of the above IL systems:namely,the wide electrochemical window with exceptionally high anodic stability.It was demonstrated that aluminium electrodes are fully passivated in solutions based on derivatives of pyrrolidium with a N(SO 2CF 3)2Àanion and LiN(SO 2CF 3)2.35Hence,in contrast to alkyl carbonate-based solutions in which LiN(SO 2CF 3)2has limited usefulness as a salt due to the poor passivation of aluminium in its solutions in the above IL-based systems,the use of N(SO 2CF 3)2Àas the anion doesn’t limit their anodic stability at all.In fact it was possible to demonstrate prototype graphite/LiMn 1.5Ni 0.5O 4and Li/L-iMn 1.5Ni 0.5O 4cells operating even at 60 C insolutionsScheme 1A reaction scheme for all possible reduction paths of EC that form passivating surface species (detected by FTIR,XPS,Raman,and SSNMR 28–31,49).Fig.3Steady-state CV response of a Pt electrode in three IL solutions,as indicated.(See structure formulae presented therein.)The CV presentations include insets of steady-state CVs of four electrodes,as indicated:Li,Li–Si,LiCoO 2,and LiMn 1.5Ni 0.5O 4.34D o w n l o a d e d b y B e i j i n g U n i v e r s i t y o f C h e m i c a l T e c h n o l o g y o n 24 F e b r u a r y 2011P u b l i s h e d o n 23 F e b r u a r y 2011 o n h t t p ://p u b s .r s c .o r g | d o i :10.1039/C 0J M 04225Kcomprising alkyl piperidium-N(SO2CF3)2as the IL solvent and Li(SO2CF3)2as the electrolyte.34Challenges remain in as far as the use of these IL-based solutions with graphite electrodes.22Fig.4shows the typical steady state of the CV of graphite electrodes in the IL without Li salts.The response in this graph reﬂects the reversible behavior of these electrodes which involves the insertion of the IL cations into the graphite lattice and their subsequent reduction at very low potentials.However when the IL contains Li salt,the nature of the reduction processes drastically changes.It was recently found that in the presence of Li ions the N(SO2CF3)2Àanion is reduced to insoluble ionic compounds such as LiF,LiCF3, LiSO2CF3,Li2S2O4etc.,which passivate graphite electrodes to different extents,depending on their morphology(Fig.4).22 Fig.4b shows a typical SEM image of a natural graphite(NG) particle with a schematic view of its edge planes.Fig.4c shows theﬁrst CVs of composite electrodes comprising NG particles in the Li(SO2CF3)2/IL solution.These voltammograms reﬂect an irreversible cathodic wave at theﬁrst cycle that belongs to the reduction and passivation processes and their highly reversible repeated Li insertion into the electrodes comprising NG. Reversible capacities close to the theoretical ones have been measured.Fig.4d and e reﬂect the structure and behavior of synthetic graphiteﬂakes.The edge planes of these particles are assumed to be much rougher than those of the NG particles,and so their passivation in the same IL solutions is not reached easily. Their voltammetric response reﬂects the co-insertion of the IL cations(peaks at0.5V vs.Li)together with Li insertion at the lower potentials(<0.3V vs.Li).Passivation of this type of graphite is obtained gradually upon repeated cycling(Fig.4e), and the steady-state capacity that can be obtained is much lower than the theoretical one(372mA h gÀ1).Hence it seems that using graphite particles with suitable morphologies can enable their highly reversible and stable operation in cyclic ammonium-based ILs.This would make it possible to operate high voltage Li-ion batteries even at elevated temperatures(e.g. 4.7–4.8V graphite/LiMn1.5Ni0.5O4cells).34 The main challenge in thisﬁeld is to demonstrate the reasonable performance of cells with IL-based electrolytes at high rates and low temperatures.To this end,the use of different blends of ILs may lead to future breakthroughs.Current collectorsThe current collectors used in Li-ion systems for the cathodes can also affect the anodic stability of the electrolyte solutions.Many common metals will dissolve in aprotic solutions in the potential ranges used with advanced cathode materials(up to5V vs.Li). Inert metals such as Pt and Au are also irrelevant due to cost considerations.Aluminium,however,is both abundantand Fig.4A collection of data related to the behavior of graphite electrodes in butyl,methyl piperidinium IL solutions.22(a)The behavior of natural graphite electrodes in pure IL without Li salt(steady-state CV is presented).(b)The schematic morphology and a SEM image of natural graphite(NG)ﬂakes.(c)The CV response(3ﬁrst consecutive cycles)of NG electrodes in IL/0.5lithium triﬂuoromethanesulfonimide(LiTFSI)solution.(d and e)Same as(b and c)but for synthetic graphiteﬂakes.DownloadedbyBeijingUniversityofChemicalTechnologyon24February211Publishedon23February211onhttp://pubs.rsc.org|doi:1.139/CJM4225Kcheap and functions very well as a current collector due to its excellent passivation properties which allow it a high anodic stability.The question remains as to what extent Al surfaces can maintain the stability required for advanced cathode materials (up to 5V vs.Li),especially at elevated temperatures.Fig.5presents the potentiodynamic response of Al electrodes in various EC–DMC solutions,considered the alkyl carbonate solvent mixture with the highest anodic stability,at 30and 60 C.37The inset to this picture shows several images in which it is demonstrated that Al surfaces are indeed active and develop unique morphologies in the various solutions due to their obvious anodic processes in solutions,some of which lead to their effective passivation.The electrolyte used has a critical impact on the anodic stability of the Al.In general,LiPF 6solutions demonstrate the highest stability even at elevated temperatures due to the formation of surface AlF 3and even Al(PF 6)3.Al CCs in EC–DMC/LiPF 6solutions provide the highest anodic stability possible for conventional electrode/solution systems.This was demonstrated for Li/LiMn 1.5Ni 0.5O 4spinel (4.8V)cells,even at 60 C.36This was also conﬁrmed using bare Al electrodes polarized up to 5V at 60 C;the anodic currents were seen to decay to negligible values due to passivation,mostly by surface AlF 3.37Passivation can also be reached in Li(SO 2CF 3),LiClO 4and LiBOB solutions (Fig.5).Above 4V (vs.Li),the formation of a successful passivation layer on Al CCs is highly dependent on the electrolyte formula used.The anodic stability of EC–DMC/LiPF 6solutions and Al current collectors may be further enhanced by the use of additives,but a review of additives in itself deserves an article of its own and for this readers are again referred to the review by Xu.32When discussing the topic of current collectors for Li ion battery electrodes,it is important to note the highly innovative work on (particularly anodic)current collectors by Taberna et al.on nano-architectured Cu CCs 47and Hu et al.who assembled CCs based on carbon nano-tubes for ﬂexible paper-like batteries,38both of whom demonstrated suberb rate capabilities.39AnodesThe anode section in Fig.1indicates four of the most promising groups of materials whose Li-ion chemistry is elaborated as follows:1.Carbonaceous materials/graphite:Li ++e À+C 6#LiC 62.Sn and Si-based alloys and composites:40,41Si(Sn)+x Li ++x e À#Li x Si(Sn),X max ¼4.4.3.Metal oxides (i.e.conversion reactions):nano-MO +2Li ++2e À#nano-MO +Li 2O(in a composite structure).424.Li x TiO y electrodes (most importantly,the Li 4Ti 5O 12spinel structure).43Li 4Ti 5O 12+x Li ++x e À#Li 4+x Ti 5O 12(where x is between 2and 3).Conversion reactions,while they demonstrate capacities much higher than that of graphite,are,practically speaking,not very well-suited for use as anodes in Li-ion batteries as they generally take place below the thermodynamic limit of most developed electrolyte solutions.42In addition,as the reactions require a nanostructuring of the materials,their stability at elevated temperatures will necessarily be an issue because of the higher reactivity (due to the 1000-fold increase in surface area).As per the published research on this topic,only a limited meta-stability has been demonstrated.Practically speaking,it does not seem likely that Li batteries comprising nano-MO anodes will ever reach the prolonged cycle life and stability required for EV applications.Tin and silicon behave similarly upon alloying with Li,with similar stoichiometries and >300%volume changes upon lith-iation,44but the latter remain more popular,as Si is much more abundant than Sn,and Li–Si electrodes indicate a 4-fold higher capacity.The main approaches for attaining a workable revers-ibility in the Si(Sn)–Li alloying reactions have been through the use of both nanoparticles (e.g.,a Si–C nanocomposites 45)and composite structures (Si/Sn–M1–M2inter-metalliccompounds 44),both of which can better accommodate these huge volume changes.The type of binder used in composite electrodes containing Si particles is very important.Extensive work has been conducted to determine suitable binders for these systems that can improve the stability and cycle life of composite silicon electrodes.46As the practical usage of these systems for EV applications is far from maturity,these electrodes are not dis-cussed in depth in this paper.However it is important to note that there have been several recent demonstrations of how silica wires and carpets of Si nano-rods can act as much improved anode materials for Li battery systems in that they can serveasFig.5The potentiodynamic behavior of Al electrodes (current density measured vs.E during linear potential scanning)in various solutions at 30and 60 C,as indicated.The inset shows SEM micrographs of passivated Al surfaces by the anodic polarization to 5V in the solutions indicated therein.37D o w n l o a d e d b y B e i j i n g U n i v e r s i t y o f C h e m i c a l T e c h n o l o g y o n 24 F e b r u a r y 2011P u b l i s h e d o n 23 F e b r u a r y 2011 o n h t t p ://p u b s .r s c .o r g | d o i :10.1039/C 0J M 04225K。

Selective Deposition of Metal Nanoparticles Inside or Outside Multiwalled Carbon Nanotubes

tubular inner core is expected to yield to conﬁne-effects similar to those existing inside the pores zeolites.23Diffusion of molecules inside wide pores similarly to waterﬂowing through a pipe.It conventionally takes place following the Poiseuillediffusion,where moleculeϪmolecule colli-much higher than moleculeϪwall collisions.the size of the pore or of the pipe decreases,the interaction of the molecules with the walls cannot be neglected anymore.24Theﬂow then follows the Knud-model.If the size of the pore is further decreased tothe dynamic diameter of molecules in the gasparticular effects due to conﬁnement of the mol-the pore appear.25These effects are well-knowncase of zeolites which present cavities in the 1Ϫ10Å.They are extensively described in theof Derouane.23The existence of similar effects inpores,that is,in the nanometer range,was a mat-debate during several years.Recently,it was how-demonstrated that they also exist in organized me-soporous silicates like MCM-41and SBA-15that present few nanometers.26Similar effects are thus sus-to also exist inside CNTs.access this information and to be able to per-investigation of the catalytic properties of met-inside or outside CNTs,one has toﬁrst master the synthesis of metal nanoparticles selectively localized in-outside of carbon nanotubes.Several groups al-attempted such localized selective deposition.main synthesis routes were suggested:(1)Deposi-vature and the size of the inner cavity are changed, and hence no curvature/conﬁnement effects can duced from the catalytic behavior.(2)Asymmetric tionalization.Theﬁrst asymmetric functionalization reported by Lee et al.who managed to graft different functional groups on each tip of the same CNT. similar concept was used by Jiang et al.to perform the asymmetric functionalization of the innerouter surface of opened CNTs.29Chen et ed dation with nitric acid to functionalize capedand,depending on the reaction conditions,tively open their ends.30Functionalization deeply modiﬁes the surface properties of the CNTs.ever,none of these reports mentions effectsported metal nanoparticles.The characterization of the sample is not straightfor-ward with respect to the localization of the supported metal nanoparticles.Winter et al.,as well as Ersen demonstrated that metal nanoparticles supported CNTs are difﬁcult to localize from conventionalview TEM images because of ambiguous estimates projection effects.31,32It is nearly impossible tomine the3D location in a2D image for particlespear to be in the center of the tube or next toner wall of the tube without tilting the specimen TEM.Electron tomography(3D TEM)appears to suitable technique that can clearly evidence the location of the particle with respect to the nanotube and further yields some statistics about the ratioticles inside and outside the CNTs.(A)SEM image of the pristine CNTs.Inset:HRTEM image of a CNT tip.(B)Statistical distribution of theirdiam-organic nanopar-in-CNTslocal-selectingtolo-from pH1.5to9.5.Deprotonation of the functional groups occurs whenever the HNO3-treated CNTs are in contact with water,thus leaving a negatively charged carbon surface.This surface charge improves signiﬁ-cantly the interaction between the CNT and metal cat-ions of the precursors used during the subsequent im-pregnation.The functional groups attract the M xϩions and help their dispersion,thus leading to metal nano-particles evenly decorating the CNTs after calcination and reduction.Selective Deposition of Metal Nanoparticles Inside CNTs.In-cipient wetness impregnation is a well-known tech-nique used for catalyst preparation.35A solid catalyst support is brought in contact with a solution contain-ing the metal precursor.The volume of this solution is adjusted to the porous volume of the solid so that it to-Figure2.SEM images of the1wt%Ni/CNT sample prepared by incipient wet-ness impregnation.The same area was acquired in SE(left)and TE(right)mode.of the external surface and an image tubule.Figure2shows that many particles outside the CNT,in agreement with Ersen believe that during the incipient wetness impregna-process,the aqueous solution containingmainlyﬁlls the inner channel.However,tension of water(72mN·mϪ1)is lowercritical surface tension of the CNTs(180mNof the CNT surface with the Ni precursor cannot be avoided.The external surface of also covered with solution,which leadsthe calcination and reduction of Ni nanoparti-the outer surface.based our new synthesis procedure onsurface of the CNTs.Hence,a higherexpected.Because of its low surface tension),the ethanolic solution wets the nanotubeandﬁlls the inner channel,as describedLaplace equation.36In a second step,distilled water are then added.The functionaliza-with nitric acid created many oxygen-containing groups which decrease the hydrophobic of the CNT surface and allow its wetting organic and aqueous solvents(contactHowever,the intrinsic lipophilicity of theleads to lower liquid/solid interface energiessolvents than for aqueous ones.Thereforephase is expected to remain outsideand to displace the thinﬁlm of ethanolic located on the outer surface to the innersample is dried at room temperature overnight at323K for10h to remove any remainingThe sample isﬁnally calcined in air atreduced in pure hydrogen at673K forreference sample prepared by the incipientSchematic view of a longitudinal crossnanotube during the different steps for deposition of nanoparticles inside CNTs:(a)impregna-the ethanolic solution containing the metalimpregnation with distilled water to washthe outer surface from metal deposition;c) calcination,and reduction,metal particles are inner surface of the CNT with a high selectivity.Representative TEM image of the sampleprepared by2-step impregnation.Most of nanoparticles seem to be inside the tubule.boiling for organic corre-nano-solvents is order to pro-In atheaqueous solution containing the Ni precursor.Finally,all samples were dried,calcined,and reduced in the same conditions as previously.The SEM investigation at low accelerating voltage shows that small nanoparti-cles are homogeneously decorating the outer surface of the CNTs (Figure 4).The choice of the solvent A af-fected neither the Ni particle dispersion on the CNT sup-port nor the particle size distribution.TEM investiga-tion conﬁrmed that particles with diameters ranging from 3to 10nm are homogeneously decorating the whole external surface of the CNTs (Figure 5).Conse-quently,it appears that the physical properties of sol-vent A do not have a signiﬁcant impact on the ﬁnal ma-terial when synthesized under our conditions.Usedthe point (K)Figure 4.SEM images of 1wt %Ni/CNT samples “metal outside”prepared with solvents of various boiling point and solubility in water (A,benzene;B,ethanol;C,octane;D,N ,N -dimethylformamide).The nature of the solvent affects neither the dispersion nor the average particle size.Figure 5.TEM images obtained for the samples “metal outside”prepared with different organic solvents:ethylene glycol (left),tetrahydrofuran (right).The nature of the solvent affects neither the dispersion nor the particle size.Additional experiments that are not reported here show that the boiling point of solvent A has the initial drying step is done at higher tempera-example,at a temperature close to or higher the boiling point of the solvent.In this case,evaporates and therefore no longer protects channel.The aqueous solution containing goes into the nanotube by capillarity,thus of selectivity.From Table 1,it is also worth other parameters,like the polaritiy of solvent not seem to play a role during the synthesis.dispersion and size distribution of the Ni for all samples make us conclude that the neither chemically modiﬁes the external Figure 6.TEM tilt series obtained by tilting the sample “metal outside”prepared with octane from ؊35°to ؉40°.Figure 7.(A)Typical 2D-TEM image of the sample “metal inside”,used to reconstruct its volume.(B)Longitudinal section through the reconstructed volume.(C)Modeling of the reconstructed volume:(pink)carbon nanotube,(red)Ni particles inside the tube,(blue)Ni particles on the external surface).2.Schematic view of a longitudinal cross section nanotube during the different steps for the deposition of nanoparticles outside CNTs:(a)impregna-with the organic solvent to protect the inner tubule metal deposition;(b)impregnation with the aqueous containing the metal precursor;(c)after drying,and reduction,metal particles are decorating surface of the CNT with a high selectivity.Figure8.(A)One of the2D-TEM images from the tilts series used for 3D-TEM analysis of the sample“metal outside”prepared with ben-zene.(B)Transeversal and a longitudinal sections through the vol-ume obtained by reconstruction.erentially outside decoration of the tube.A typical pro-jection of the object and several sections through the volume as obtained from the reconstruction are pre-sented in Figure8.By extracting the nanoparticles and nanotube contributions from the total volume,we ob-tained the exact position of the nanoparticles with re-spect to the outer surface and estimated thus the ratioinside/outside in the case of the two-step impregnation process proposed here.For this sample,the selectivityof particles deposited on the outer surface is ratherhigh,close to85%.The higher selectivity for the exter-nal deposition was attributed to the fact that the aque-ous solution evaporation on the outer surface was moreefﬁcient,as all the solution is in direct contact with air.The evaporation of the organic solvent is much sloweras itﬁlls the tubule and it is in contact with air only atthe tube tips.For both types of samples,“metal inside”and“metal outside”,the particle size ranges from3to7nm for the particles inside and4to9nm for the par-ticles outside.These values are inline with the SEM andTEM observations(Figures3Ϫ6)and conﬁrm that thenature of the solvent affects neither the dispersion northe average particle size.CONCLUSIONSelective,localized deposition of metal nanoparti-cles on carbon nanotubes is possible by using a combi-nation of organic and aqueous solvents.By testing dif-ferent solvents we demonstrated that other parameterslike the miscibility with water and the boiling pointhave no crucial effect in our synthesis conditions.The difference in the liquid/solid interface energies of both solvents with the CNT surface is a crucial parameter.This method allows the avoidance of any additional。

静电纺丝法制备纳米氧化铟锡及其导电性能

收稿日期：2020⁃10⁃06。

收修改稿日期：2020⁃11⁃13。

中央高校基本业务费(No.3207042009C2)资助。

#共同第一作者。

＊通信联系人。

E⁃mail ：************.cn ，***********.cn第37卷第3期2021年3月Vol.37No.3491⁃498无机化学学报CHINESE JOURNAL OF INORGANIC CHEMISTRY静电纺丝法制备纳米氧化铟锡及其导电性能任鑫川#刘苏婷#李志慧宋承堃代云茜＊孙岳明＊(东南大学化学化工学院，南京211189)摘要：采用静电纺丝-溶胶凝胶法，以SnCl 2、InCl 3、聚乙烯吡咯烷酮(PVP)等为原料，乙醇胺为水解控制剂，合成了超细氧化铟锡(ITO)纳米纤维及富氧缺陷的ITO 纳米颗粒。

采用透射电子显微镜(TEM)、选区电子衍射(SAED)、扫描电子显微镜(SEM)、热重分析(TGA)、X 射线衍射(XRD)、X 射线电子能谱(XPS)、四探针电阻仪，系统研究了超细ITO 纤维及颗粒的形貌、晶型、氧缺陷及导电性能。

在400℃空气煅烧后，纤维中的PVP 高分子骨架发生热分解，获得超细、多孔ITO 纳米纤维，晶型为立方相。

进一步升高煅烧温度至800℃，ITO 纳米纤维转变为富氧缺陷的纳米颗粒，晶格氧空位含量高达38.9%。

随着煅烧温度升高，Sn 4+掺入到In 2O 3晶格中，发生晶格膨胀，晶面间距增大。

煅烧温度由400℃升高至800℃，未发生立方相向六方相的转变，晶型稳定，晶粒尺寸从32nm 生长到44nm ，晶格应变(ε0)从1.943×10-3减小至1.422×10-3，应变诱导的晶格弛豫逐渐减小。

此外，高温煅烧可抑制In 2O 3晶粒(111)晶面的增长，随着In 2O 3的(400)与(222)晶面比值(I (400)/I (222))的增加，ITO 电导率逐渐升高。

在800℃获得的ITO 纳米颗粒导电率最高。

Chapter 3 Self-Diffusion and Impurity Diffusion in Group III Metals

(References, see page 145)
(11) (12) Figure Reference
(1)
(2a)
(2b)
(3)XD Q (eV Nhomakorabea and D(Tm) T-range (K) (10À4 m2 sÀ1) (kJ moleÀ1) (10À12 m2 sÀ1) ðT =T m Þ
0
Self-Diffusion and Impurity Diffusion in Group III Metals
Sc b hcp 1,608 1,812 0.453 0.331 0.527 1.59
Y a hcp 1,752 1,803 0.363 0.575 1.58 b fcc
La g bcc 1,134 1,193 0.531
Al fcc 933 0.404
In fct 430 0.458 0.494 1.07 a hcp
123
124
Table 3.2
(4) T-range (K) ðT =T m Þ No. of data points 5 5 sc61 1 example
91
Self-diffusion and impurity diffusion in a-yttrium
(5) Material, purity Experimental method Remarks on the pp Further remarks Also studied (6) (7) (8) (9) (10) (11)
Tl b bcc 507 577 0.345 0.387 0.551 1.60
Table 3.1 Impurity diffusion in scandium

High-powerlithiumbatteriesfromfunctionalizedcarbon-nanotubeelectrodes

High-power lithium batteries from functionalized carbon-nanotube electrodesSeung Woo Lee 1†,Naoaki Yabuuchi 2†,Betar M.Gallant 2,Shuo Chen 2,Byeong-Su Kim 1,Paula T.Hammond 1and Yang Shao-Horn 2,3*Energy storage devices that can deliver high powers have many applications,including hybrid vehicles and renewable energy.Much research has focused on increasing the power output of lithium batteries by reducing lithium-ion diffusion distances,but outputs remain far below those of electrochemical capacitors and below the levels required for many applications.Here,we report an alternative approach based on the redox reactions of functional groups on the surfaces of carbon yer-by-layer techniques are used to assemble an electrode that consists of additive-free,densely packed and functionalized multiwalled carbon nanotubes.The electrode,which is several micrometres thick,can store lithium up to a reversible gravimetric capacity of ∼200mA h g 21electrode while also delivering 100kW kg electrode 21of power and providing lifetimes in excess of thousands of cycles,both of which are comparable to electrochemical capacitor electrodes.A device using the nanotube electrode as the positive electrode and lithium titanium oxide as a negative electrode had a gravimetric energy ∼5times higher than conventional electrochemical capacitors and power delivery ∼10times higher than conventional lithium-ion batteries.Amajor challenge in the ﬁeld of electrical energy storage is to bridge the performance gap between batteries and electroche-mical capacitors by developing materials that can combine the advantages of both devices.Batteries exhibit high energy as a result of Faradaic reactions in the bulk of active particles,but are rate-limited.Electrochemical capacitors 1–3can deliver high power at the cost of low energy storage by making use of surface ion adsorption (referred to as double-layer capacitance)and surface redox reactions (referred to as pseudo-capacitance).Lithium rechargeable batteries ( 150W h kg cell 21and 1kW kg cell 21)therefore have higher gravimetric energy but lower power capability than electrochemical capacitors ( 5W h kg cell 21and 10kW kg cell 21)1.Energy and power versatility are crucial for hybrid applications 2.For example,although conventional batteries have been used in light vehicles,hybrid platforms for heavy vehicles and machineries demand delivery of much higher currents,so higher energy and comparable power capability relative to electrochemical capacitors are needed to meet this demand 1,2.Considerable research efforts have been focused on increasing the power characteristics of lithium rechargeable batteries by redu-cing the dimensions of lithium storage materials down to the nano-metre scale 4–12,which would reduce the lithium diffusion time that accompanies the Faradaic reactions of active particles.However,nanostructured lithium storage electrodes 5,13still have a lower power capability than electrochemical capacitor electrodes.On the other hand,researchers have shown that the gravimetric energy of electrochemical capacitors can be increased by using electrode materials with enhanced gravimetric capacitances (gravimetric charge storage per volt),which can be achieved through the use of carbon subnanometre pores for ion adsorption 1,14or by taking advantage of the pseudocapacitance of nanostructured transition metal oxides 15–17.The high cost of ruthenium-based oxides is prohibitive for many applications,and the cycling instability of manganese-based oxides 17–19remains a major technical challenge.A promising approach is to use the Faradaic reactions of surface functional groups on nanostructured carbon electrodes,which can store more energy than the double-layer capacitance on convention-al capacitor electrodes 1and also provide high power capability.Here,we report the use of an entirely different class of electrodes for lithium storage,which are based on functionalized multiwalled carbon nanotubes (MWNTs)that include stable pseudo-capacitive functional groups,and are assembled using the layer-by-layer (LBL)technique 20.These additive-free LBL-MWNT electrodes exhibit high gravimetric energy (200W h kg electrode 21)delivered at an exceptionally high power of 100kW kg electrode 21in Li /LBL-MWNT cells when normalized to the single-electrode weight,with no loss observed after completing thousands of cycles.LBL-MWNT electrodes show signiﬁcantly higher gravimetric energy not only over electrochemical capacitor electrodes,but also over high-power lithium battery electrodes,with gravimetric powers greater than 10kW kg electrode 21.In addition,cells (analogous to asymmetric electrochemical capacitors)consisting of LBL-MWNTs and a lithiated Li 4Ti 5O 12(LTO)negative electrode have comparable gravimetric energy to LTO /LiNi 0.5Mn 1.5O 4cells 21at low gravimetric power,but can also deliver much higher energy at higher power.Gravimetric energy and power at the cell level may be estimated by dividing these values based on LBL-MWNT weight by a factor of 5(ref.22).Furthermore,we show that the Faradaic reactions between the lithium ions and the surface functional groups on the MWNTs are responsible for the high gravimetric energy found in Li /LBL-MWNT and LTO /LBL-MWNT cells.Physical characteristics of LBL-MWNT electrodesStable dispersions of negatively and positively charged MWNTs were obtained by functionalization of the exterior surfaces with car-boxylic-acid (MWNT–COOH)and amine-containing (MWNT–NH 2)groups,respectively 23.Uniform MWNT electrodes on glass1Department of Chemical Engineering,Massachusetts Institute of T echnology,Cambridge,Massachusetts 02139,USA,2Department of Mechanical Engineering,Massachusetts Institute of T echnology,Cambridge,Massachusetts 02139,USA,3Department of Materials Science and Engineering,Massachusetts Institute of T echnology,Cambridge,Massachusetts 02139,USA;†These authors contributed equally to this work.*e-mail:shaohorn@coated with indium tin oxide (ITO)(Fig.1a)were assembled by alternate adsorption of charged MWNTs 23.Electrode thickness increases linearly with the number of positively and negatively charged layer pairs (bilayers),as shown in Fig.1b.The transparency of the MWNT ﬁlms decreased linearly with increasing thickness up to 0.3m m (Fig.1b).The ﬁlms were then heat-treated sequentially at 1508C in vacuum for 12h,and at 3008C in H 2for 2h to increase ﬁlm mechanical stability and electrical conductivity bined proﬁlometry and quartz crystal microbalance measurements gave an electrode density of 0.83g cm 23(Supplementary Fig.S1)follow-ing the heat treatments,which is one of the highest densities reported for carbon nanotube electrodes 24,25.Cross-sectional scan-ning electron microscope (SEM)images showed that the individual MWNTs were randomly distributed throughout the ﬁlm thickness,and the MWNT ﬁlms were uniform and conformal on the substrate (Fig.1c).Moreover,the LBL-MWNT electrodes had an inter-connected network of individual MWNTs (Fig.1c,inset)with well-distributed pores of 20nm,as revealed by transmission electron microscopy (TEM)imaging of an LBL-MWNT electrode slice (Fig.1d).Role of surface functional groups on LBL-MWNTelectrodesX-ray photoemission spectroscopy (XPS)analysis of the LBL-MWNT electrodes after heat treatment revealed that signiﬁcant amounts of oxygen-containing and nitrogen-containing surface functional groups remained on the nanotube surface.The atomic composition of a representative LBL-MWNT electrode was found to be 85.7%carbon,10.6%oxygen and 3.7%nitrogen (C 0.86O 0.11N 0.04;Supplementary Table S1).The presence of two dis-tinct peaks (531.7+0.1eV and 533.4+0.1eV)in the O 1s spectrum (Supplementary Fig.S2a)could be attributed to oxygen atoms inthe carbonyl groups 26,27and various other oxygen groups (Supplementary Fig.S2c)bound to the edges 26,28of the graphene sheets forming the MWNT sidewalls.High-resolution TEM images of functionalized MWNTs revealed that acid treatments roughened the exterior walls of the MWNTs (Supplementary Fig.S3),exposing carbon atoms on the edge sites.Edge carbon atoms are known to bind with oxygenated species more strongly than carbon atoms in the basal plane 29,which is in good agreement with the XPS ﬁnding that more oxygenated species are detected on LBL-MWNT electro-des than on pristine MWNTs.In addition,the chemical environment of the nitrogen atoms in the LBL-MWNT electrodes was mostly in the form of amide groups (Supplementary Fig.S2b),as indicated by the N 1s peak centred at 400.1eV (ref.30).Two small additional peaks in the N 1s spectrum suggest that some nitrogen atoms are pyr-idinic N-6(ref.30)(398.5+0.1eV)and tied in oxidized nitrogen-containing functional groups (402.3eV)30.These surface functional groups can undergo Faradaic reactions,as indicated by the potential-dependent gravimetric capacitance obtained from cyclic voltammetry measurements (Fig.2a).The typical gravi-metric capacitance of LBL-MWNT electrodes in the voltage range 3–4.25V versus Li (with a comparable voltage scale of 0to 1.2V versus standard hydrogen electrode (SHE))is 125F g 21,which is comparable to the values reported for functionalized MWNTs 23,31and porous carbon materials 32,33in aqueous solutions.Reducing the lower potential limit from 3.0to 1.5V led to a signiﬁcant increase in the gravimetric capacitance from 125to 250F g 21measured at 4.0and 2.5V versus Li.Recent studies have shown that carbonyl (C ¼O)groups can be reduced by Li þand reversibly oxidized in the voltage range from 3.5to 1.5V versus Li in aromatic carbonyl derivative organic materials such as poly(2,5-dihydroxy-1,4-benzoqui-none-3,6-methylene)34and Li 2C 6O 6(ref.35).It is thereforepostulated0.00.51.01.52.02.53.03.5acbdT h i c k n e s s (µm )Number of bilayersFigure 1|Physical characteristics of LBL-MWNT electrodes.a ,Digital image of representative MWNT electrodes on ITO-coated glass slides.The number on each image indicates the number of bilayers (n )in (MWNT–NH 2/MWNT–COOH)n .b ,Thickness of the LBL-MWNT electrodes as a function of the number of bilayers.A linear relationship is apparent for LBL-MWNT electrodes with thicknesses from 20nm to 3m m.Error bars show the standard deviation of the thickness,computed from three samples for each thickness.T ransmittance measured at 550nm as a function of the number of bilayers is shown in the inset.Error bars show the standard deviation of transmittance computed from three measurements.c ,SEM cross-sectional image of an LBL-MWNT electrode on an ITO-coated glass slide after heat treatments.A higher-magniﬁcation image is shown in the inset,revealing that MWNT s are entangled in the direction perpendicular to the electrode surface.d ,TEM image of an LBL-MWNT electrode slice,showing pore sizes of the order of 20nm.DOI:10.1038/NNANO.2010.116that the doubled gravimetric capacitance obtained from lowering the lower voltage limit of Li /LBL-MWNT cells (with open-circuit voltages of 3.2V)from 3.0to 1.5V versus Li can be attributed to the Faradaic reactions of surface oxygen on LBL-MWNTs,such as C ¼O LBL-MWNT þLi þþe 2↔C 2OLi LBL-MWNT ,which can become accessible at vol-tages lower than 3V versus Li.The role of surface functional groups in providing high capaci-tances in LBL-MWNTs was further conﬁrmed by comparing the speciﬁc capacitance of LBL-MWNTs before and after exposure to 4%H 2and 96%Ar by volume at 5008C for 10h.The gravimetric current and capacitance values of the LBL-MWNTelectrode decreased considerably (by 40%)after this heat treatment,as shown in Fig.2b.XPS analysis showed that this high-temperature heat treatment decreased the amount of surface oxygen and nitrogen functional groups on the MWNTs.The intensities of the distinct C 1s peaks (assigned to carbon atoms in C 2N (ref.36)or C 2O (ref.37)centred at 285.9+0.1eV,carbonyl C ¼O (refs 27,37)groups at 286.7+0.1eV,and amide N 2C ¼O or carboxylic COOR groups at 288.4+0.1eV (ref.36))were greatly reduced (by 70%)relative to those of sp 2(284.5eV)and sp 3(285.2eV)hybridized carbon 37follow-ing heat treatment,as shown in Fig.2c.This experiment therefore pro-vides further evidence that the redox of surface oxygen-containing functional groups with lithium ions is responsible for the large gravi-metric capacitances of LBL-MWNT electrodes in organic electrolytes.The contribution of double-layer capacitance to LBL-MWNT capacitances is relatively small compared to that of Faradaic reactions,and can be estimated by comparing cyclic voltammograms of compo-site electrodes (80wt%MWNTs and 20wt%binder)that include pristine MWNTs with those containing functionalized MWNTs(see Supplementary Information).Composite electrodes with MWNT–COOH and MWNT–NH 2show much higher gravimetric capacitances (factor of 2)than pristine MWNTs (Fig.2d;Supplementary Fig.S4),indicating the dominant contribution from the surface functional groups.In addition,we show that surface func-tional groups on MWNTs are better used in LBL-MWNT electrodes than in composite electrodes.The capacitance normalized to MWNT weight for LBL-MWNT electrodes is 2.5times higher than that of con-ventional composite electrodes (Fig.2d).Considering that the MWNT–COOH and MWNT–NH 2in the composite electrodes have similar ratios of carbon and oxygen atomic percentages as the LBL electrodes (Supplementary Table S1),this result suggests that the binder-free porous network structure of LBL-MWNT electrodes allows better utilization of the surface functional groups than compo-site electrodes with binder,which can block the redox of the surface functional groups.Moreover,the volumetric capacitances of LBL-MWNT electrodes are even greater (by a factor of 5)than those of composite MWNT electrodes because of their higher elec-trode density (0.83g cm 23for LBL-MWNTs versus 0.45g cm 23for composite electrodes).Lithium storage characteristics of LBL-MWNT electrodesThe speciﬁc and volumetric capacitances of LBL-MWNT electrodes are greater than those of conventional composite electrodes based on carbon 32,38in organic electrolytes.Because LBL-MWNT electrodes have no additives,the gravimetric capacitance normalized to electrode weight is identical to that normalized to MWNT weight.It is interesting to point out that the gravimetric capacitances of these LBL-MWNT electrodes are comparable to those of12345−1.0−0.50.00.51.0acbdI (A g M W N T −1)I (A g M W N T −1)I (A g M W N T −1)E (V versus Li)−1,000−50005001,0001.48 ± 0.14 µm at 1 mV s −10.31 ± 0.01 µm at 1 mV s −10.31 ± 0.01 µm at 1 mV s −1PVdF-MWNT (pristine)PVdF-MWNT (−NH 2)PVdF-MWNT (−COOH)3.0 −4.25 VBefore 500 °C H 2 treatmentBefore 500 °C H 2 treatment After 500 °C H 2 treatmentAfter 500 °C H 2 treatment4.2 V4.5 V4.5 V4.2 V d Q /d E (F g MWNT −1)d Q /d E (F g MWNT −1)d Q /d E (F g MWNT −1)12345−0.6−0.30.00.30.6−600−300300600E (V versus Li)292290288286284282C 1s LBL-MWNTC−NN−C C−O sp 2−Csp 3−CI n t e n s i t y (a .u .)Binding energy (eV)12345−1.0−0.50.00.51.0−1,000−5005001,000E (V versus Li)−−O−−O COOR C Figure 2|Potential-dependent electrochemical behaviour of LBL-MWNT and functionalized MWNT composite electrodes measured in two-electrode lithium cells.a ,Cyclic voltammogram data for an LBL-MWNT electrode obtained with different upper-and lower-potential limits.Reducing the lower-potential limit from 3to 1.5V versus Li resulted in increased current and gravimetric capacitance.b ,Cyclic voltammogram data for an LBL-MWNT electrode before and after 5008C H 2-treatment in 4%H 2and 96%Ar by volume for 10h.c ,XPS C 1s spectra of an LBL-MWNT electrode before and after this additional heat treatment,which is seen to remove a considerable amount of surface oxygen and nitrogen functional groups from the MWNT surface.d ,Cyclic voltammogram data for an LBL-MWNT electrode and composite electrodes of pristine MWNT,MWNT–COOH and MWNT–NH 2,with the LBL-MWNT electrode having higher current and capacitance normalized to the MWNT weight than the composite electrodes.The composite electrodesconsisted of 20wt%PVdF and 80wt%posite MWNT electrodes were prepared from slurry casting and dried at 1008C for 12h under vacuum.The thickness of the LBL-MWNT electrode was 0.3m m,and the thicknesses of the pristine MWNT,MWNT–COOH and MWNT–NH 2composite electrodes were 40,50and 30m m,respectively.The density of the composite electrodes was 0.45g cm 23.DOI:10.1038/NNANO.2010.116nanostructured composite electrodes with manganese-based oxides ( 40wt%oxides),even though higher capacitances normalized toactive material mass only (for example,up to 600F g MnO221;ref.39)are typically reported.Moreover,taking into account the LBL-MWNT electrode density of 0.83g cm 23,we obtain a volumetric capacitance of 180F cm 23for LBL-MWNT electrodes,which is higher than that of nanostructured carbon ( 50F cm 23)in organic electrolytes 32and nanostructured MnO 2electrodes( 150F cm 23)in aqueous electrolytes 16,40.Very few studies have reported the volumetric capacitance of entire electrodes,and we note that this is,to our knowledge,the highest value reported.Storing energy on the surfaces of MWNTs enables LBL-MWNT electrodes to have a high rate capability.For a given thickness,the current at 3V was found to increase linearly with scan rate from cyclic voltammetry,indicating a surface-redox limited process (Fig.3a,including inset),which is in good agreement with the proposed mechanism of redox of functional groups on MWNT surfaces.LBL-MWNT electrodes were also examined by means of galvanostatic measurements,allowing direct comparison with the performance of high-power battery materials.The gravi-metric capacity of 0.3-m m electrodes was found to be 200mA h g 21at low rates such as 0.4A g 21,which is in good agreement with the estimated capacity of LBL-MWNT electrodes based on the proposed Faradaic reaction between Li and surface oxygen (C 0.86O 0.11N 0.04).Half of the gravimetric capacity (100mA h g 21)was retained at exceptionally high discharge rates of 180A g 21(corresponding to full discharge in less than 2s),as shown in Fig.3b.Moreover,the capacity (stored charge)of LBL-MWNT electrodes increases linearly with electrode thickness (Fig.3c,inset),and a high power capability is maintained with elec-trode thickness increasing to 3m m (Supplementary Fig.S5).The speciﬁc energy and power of LBL-MWNTelectrodes with thick-nesses up to 3.0m m,in the 1.5–4.5V range,are shown in Fig.4a (for volumetric energy and power data see Supplementary Fig.S7).Although the powercapabilityof LBL-MWNTelectrodes reduces some-what with increasing thickness,electrodes of 3.0m m can still deliver a very high gravimetric energy of 200W h kg electrode 21at a large gravimetric power of 100kW kg electrode 21,based on single-electrode weight alone.At low powers,their gravimetric energy ( 500W h kg electrode 21)approaches that of LiFePO 4and LiCoO 2(refs 5,35,41;Supplementary Fig.S6).At high powers (greater than 10kW kg electrode 21),LBL-MWNT electrodes show higher gravimetric energy than carbon-nanotube-based electrodes for electrochemical capacitors ( 70W h kg electrode 21;ref.25),thin-ﬁlm batteries 22,nano-structured lithium battery materials 5,13and high-power lithium battery materials 4,42(Supplementary Fig.S6).As conventional composite electrodes are much thicker than the 3.0-m m LBL-MWNT elec-trodes (.10times),where ion transport in the electrodes can limit power capability,future studies are needed to examine how the power and energy performance of LBL-MWNT electrodes changes with thicknesses up to tens and hundreds of micrometres.LBL-MWNT electrodes can be tested over 1,000cycles without any observable capacity loss,as shown in Fig.4b.Further cycling of a 1.5-m m LBL-MWNT electrode revealed no capacity loss up to 2,500cycles,even after the cell was left open circuit for 30days (Supplementary Fig.S8).The voltage proﬁles in the ﬁrst and 1,000th cycles to 4.5V are virtually unchanged (Fig.4c and Supplementary Fig.S8).TEM and XPS analysis of cycled electro-des (1,000cycles to 4.5V,followed by an additional 1,000cycles to 4.7V versus Li)provided further evidence for this cycling stab-ility,with no distinctive change being noted in the surface atomic structure and surface functional groups after cycling (Supplementary Fig.S9).The stability of the functional groups on these MWNTs is remarkable when compared to the consider-able losses of carbonyl derivative molecules within 50to 100cycles reported recently 34,35,43.We hypothesize that the cycling stability of the LBL-MWNT electrodes can be linked to the strong chemical covalent bonding of the surface functional groups on the MWNTs,in contrast to the gradual separation occurring between the active carbonyl groups and carbon addi-tives in composite electrodes during cycling.Because a lithium negative electrode is not practical for real applications,we investigated the use of LBL-MWNT electrodes with a lithiated Li 4Ti 5O 12(LTO)composite electrode (see−1.0−0.50.00.51.0a bE (V versus Li)I (m A )249 A g −1183 A g −137 A g −14.5 V(0.31±0.01 µm)550 A g −12 A g −10.4 A g −16012345E (V v e r s u s L i )E (V versus Li)70140210Q (mA h g −1)Q (µA h)12345−80−404080I (µA )c Figure 3|Electrochemical characteristics of LBL-MWNT electrodes in two-electrode lithium cells with 1M LiPF 6in a mixture of ethylene carbonate and dimethyl carbonate (volume ratio 3:7).a ,Cyclicvoltammogram data for a 0.3-m m LBL-MWNT electrode over a range of scan rates.The current at 3V versus scan rate is shown in the inset.b ,Charge and discharge proﬁles of an electrode of 0.3m m obtained over a wide range of gravimetric current densities between 1.5and 4.5V versus Li.Before each charge and discharge measurement for the data in Fig.3b,cells were held at 1.5and 4.5V for 30min,respectively.c ,Cyclic voltammogram data forelectrodes with different thicknesses collected at a scanning rate of 1mV s 21in the voltage range 1.5–4.5V versus Li.The integrated charge increases linearly with electrode thickness,as shown in the inset.DOI:10.1038/NNANO.2010.116Supplementary Information).Although the electrode gravimetric energy and power in LTO /LBL-MWNT cells is reduced due to the lower cell voltage (Fig.4d),the rate capability,gravimetric capacity and capacity retention are comparable to cells with a Li negative electrode (Supplementary Fig.S10).Interestingly,although LTO /LBL-MWNT cells show comparable gravimetric energy to LTO /LiNi 0.5Mn 1.5O 4cells at low power,they exhibit signiﬁcantly higher gravimetric energy at powers greater than10kW kg electrode 21(ref.21;Fig.4d and Supplementary Fig.S11).Using a conservative assumption that the mass of the battery is ﬁve times greater than that of the LBL-MWNT 22,which is higher than the 2.5(ref.4)typically used for conventional lithium rechargeable batteries due to reduced electrode thicknesses (such as 3m m)demonstrated in this study,LTO /LBL-MWNT storage devices are expected to deliver 30W h kg cell 21at 5kW kg cell 21.This value is signiﬁcantly higher than that of current electrochemical capacitors with a gravimetric energy of 5W h kg cell 21at 1kW kg cell 21(refs 1,32).Finally,we show that LBL-MWNT electrodes can also be used in symmetrical LBL-MWNT /LBL-MWNT cells (cell voltage in the range 0–3V).As there is no net Faradaic reaction of surface oxygen-containing functional groups on MWNTs,they exhibit speciﬁc capacitances ( 95F g 21)comparable to those (702120F g 21)in electrochemical capacitors reported previously 44,but considerably lower than that of Li /LBL-MWNT cells.Symmetric cells therefore deliver gravimetric energy comparable toconventional electrochemical capacitors 1,32,but lower than Li /LBL-MWNT and LTO /LBL-MWNT cells (Fig.4d).ConclusionsIn summary,LBL-MWNT electrodes,which are conformal,densely packed and additive-free,can exhibit gravimetric energies up to 200W h kg electrode 21at a gravimetric power of 100kW kg electrode 21,where the gravimetric energy and power at the cell level can be estimated by dividing these values by a factor of 5.The energy stored in the LBL-MWNT electrodes can be con-trolled by the electrode thickness (Fig.3c,inset)and upper voltage limit (Supplementary Fig.S12).Redox of surface oxygen-containing functional groups on LBL-MWNT electrodes by lithium ions in organic electrolytes,which can be accessed reversibly at high power,are predominantly responsible for the observed high energy and power capabilities of LBL-MWNT electrodes,as can be seen in the high-resolution TEM (HRTEM)image of the LBL-MWNT elec-trode in Fig.5.We have demonstrated energy and power capabilities of LBL-MWNT electrodes with thicknesses of a few micrometres that will open up new opportunities in the development of high-performance electrical energy storage for microsystems,and ﬂexible,thin-ﬁlm devices 22.Further research will seek to validate the reported energy and power capabilities of MWNT electrodes with thicknesses of the order of tens and hundreds of micrometres,and minimize energy loss during charge and discharge (charging voltages of LBL-MWNT107a b cd1061054.5 V (1.48 ± 0.14 µm) at 250 mA g −1104103102G r a v i m e t r i c p o w e r (W k g −1)107106105104103102G r a v i m e t r i c p o w e r (W k g −1)Gravimetric energy (W h kg −1)101102103Gravimetric energy (W h kg −1)Q (m A h g −1)Cycle number01st cycle1,000th cycle 102030012345050100150200Q (mA h g −1)E (V v e r s u s L i )Q (µA h)Figure 4|Gravimetric energy and power densities,and cycle life of LBL-MWNT electrodes obtained from measurements of two-electrode cells.a ,Ragone plot for Li /LBL-MWNT cells with different thicknesses ( 0.3–3.0m m).The corresponding loading density of LBL-MWNT electrodes ranges from 0.025–0.25mg cm 22.Only the LBL-MWNT weight was considered in the gravimetric energy and power density calculations.b ,Gravimetric capacities of Li /LBL-MWNT cells as a function of cycle number,measured at a current density of 0.25A g 21once every 100cycles,after voltage holds at the end of charging and discharging for 30min.Within each 100cycles,these cells were cycled at an accelerated rate of 2.5A g 21.c ,Voltage proﬁles of a 1.5-m m electrode in the ﬁrst and 1,000th cycles,for which negligible changes were noted.d ,Ragone plot for Li /LBL-MWNT (black squares),L TO /LBL-MWNT (green circles),L TO /LiNi 0.5Mn 1.5O 4(grey circles)and LBL-MWNT /LBL-MWNT (orange triangles)cells with 4.5V versus Li as the upper-potential limit.The thickness of the LBL-MWNT electrode was 0.3m m for asymmetric Li /LBL-MWNT and L TO /LBL-MWNT,and 0.4m m for symmetric LBL-MWNT /LBL-MWNT.Gravimetric energy and maximum power densities were reduced for the L TO /LBL-MWNT cells subjected to the same testing conditions due to a lower cell voltage.DOI:10.1038/NNANO.2010.116electrodes are higher than those on discharge,even at low rates).Large-scale thicker electrodes of tens of micrometres can be produced using a recently developed sprayed LBL system 45that uses an auto-mated process to reduce assembly time dramatically (about 70times faster than the conventional dipping of LBL systems used in this study).Modiﬁcation of the surface functional groups on carbon 46,47may allow the tuning of redox potentials and increase efﬁciency by reducing the voltage difference during charge and discharge.MethodsMaterials.MWNTs prepared by chemical vapour deposition were purchased from NANOLAB (95%purity;outer diameter,15+5nm).Carboxylated MWNTs (MWNT–COOH)and amine-functionalized MWNTs (MWNT–NH 2)wereprepared and assembled onto ITO-coated glass slides (procedures are described in detail elsewhere 23).Cross-sectional scanning electron microscope (SEM)images of MWNT electrodes after heat treatments were obtained using a JEOL 6320SEM operated at 5kV.Fabrication of layer-by-layer MWNT electrodes.MWNT–COOH and MWNT–NH 2powder samples were sonicated for several hours in Milli-Q water (18M V cm)to form a uniform dispersion,and this was followed by dialysis using Milli-Q water for several days,resulting in a stable dispersion of functionalized MWNTs in solution (0.5mg ml 21).pH values of the solutions were adjusted to pH 2.5(MWNT–NH 2)and pH 3.5(MWNT–COOH),respectively,and the solutions were sonicated for 1h just before LBL assembly.All-MWNT electrodes were assembled with a modiﬁed Carl Zeiss DS50programmable slide stainer.Details of LBLassembly of MWNT electrodes can be found elsewhere 23.Assembled LBL-MWNT electrodes were dried in air,and these ﬁlms were then heat-treated sequentially at 1508C in vacuum for 12h,and at 3008C in H 2for 2h to increase mechanical stability.X-ray photoelectron spectroscopy (XPS).A Kratos Axis Ultra XPS instrument (Kratos Analytical)with a monochromatized Al K a X-ray source was used to analyse the surface chemistry of functionalized MWNTs and LBL-MWNTelectrodes.The take-off angle relative to the sample substrate was 908.Curve ﬁtting of the photoemission spectra was performed following a Shirley-type background subtraction.An asymmetric C 1s peak from sp 2hybridized carbons centred at 284.5eV was generated for raw ing this asymmetric peak as a reference,all other peaks were ﬁtted by the Gaussian–Lorentzian function.The experimental uncertainty of the XPS binding energy was +0.1eV.The relative sensitivity factors used to scale the peaks of C 1s ,O 1s and N 1s were 0.278,0.780and 0.477,respectively.Electrochemical measurements.Electrochemical measurements were conducted using a two-electrode electrochemical cell (Tomcell)consisting of an LBL-MWNT electrode on ITO-coated glass,two sheets of microporous membrane (Celgard 2500,Celgard)and lithium foil as the counter-electrode.LBL-MWNT electrode areas of 100or 50mm 2were used for electrochemical measurements with Li foil andlithiated LTO negative electrodes.The weights of the LBL-MWNT electrodes were determined from the area and the mass area density (see SupplementaryInformation).The loading density of the LBL-MWNT electrodes ranged from 0.025to 0.25mg cm 22.A piece of aluminium foil (25m m thick and with an areaof 1mm ×7mm in contact with the LBL-MWNT electrode)was attached to one edge and used as a current collector.The electrolyte solution was 1M LiPF 6dissolved in a mixture of ethylene carbonate (EC)and dimethyl carbonate (DMC)with a 3:7volume ratio (3.5ppm H 2O impurity,Kishida Chem.).The separators were wetted by a minimum amount of electrolyte to reduce the background current.Cyclic voltammetry and galvanostatic measurements of the lithium cells were performed using a Solartron 4170at room temperature.Received 26March 2010;accepted 13May 2010;published online 20June 2010References1.Simon,P.&Gogotsi,Y.Materials for electrochemical capacitors.Nature Mater.7,845–854(2008).ler,J.R.&Simon,P.Materials science—electrochemical capacitors forenergy management.Science 321,651–652(2008).3.Amatucci,G.G.,Badway,F.,Du Pasquier,A.&Zheng,T.An asymmetric hybridnonaqueous energy storage cell.J.Electrochem.Soc.148,A930–A939(2001).4.Kang,B.&Ceder,G.Battery materials for ultrafast charging and discharging.Nature 458,190–193(2009).5.Lee,Y.J.et al .Fabricating genetically engineered high-power lithium-ionbatteries using multiple virus genes.Science 324,1051–1055(2009).6.Nazar,L.F.et al .Nanostructured materials for energy storage.Int.J.Inorg.Mater.3,191–200(2001).7.Arico,A.S.et al .Nanostructured materials for advanced energy conversion andstorage devices.Nature Mater.4,366–377(2005).8.Poizot,P.et al .Nano-sized transition-metaloxides as negative-electrodematerials for lithium-ion batteries.Nature 407,496–499(2000).9.Sides,C.R.et al .Nanoscale materials for lithium-ion batteries.MRS Bull.27,604–607(2002).10.Bruce,P.G.,Scrosati,B.&Tarascon,J.M.Nanomaterials for rechargeablelithium batteries.Angew.Chem.Int.Ed.47,2930–2946(2008).11.Tarascon,J.M.&Armand,M.Issues and challenges facing rechargeable lithiumbatteries.Nature 414,359–367(2001).12.Armand,M.&Tarascon,J.M.Building better batteries.Nature 451,652–657(2008).13.Wu,X.L.et al .LiFePO 4nanoparticles embedded in a nanoporous carbonmatrix:superior cathode material for electrochemical energy-storage devices.Adv.Mater.21,2710–2714(2009).14.Chmiola,J.et al .Anomalous increase in carbon capacitance at pore sizes lessthan 1nanometer.Science 313,1760–1763(2006).15.Hu,C.C.,Chen,W.C.&Chang,K.H.How to achieve maximum utilization ofhydrous ruthenium oxide for supercapacitors.J.Electrochem.Soc.151,A281–A290(2004).16.Fischer,A.E.et al .Incorporation of homogeneous,nanoscale MnO 2withinultraporous carbon structures via self-limiting electroless deposition:implications for electrochemical capacitors.Nano Lett.7,281–286(2007).17.Reddy,A.L.M.,Shaijumon,M.M.,Gowda,S.R.&Ajayan,P.M.CoaxialMnO 2/carbon nanotube array electrodes for high-performance lithium batteries.Nano Lett.9,1002–1006(2009).18.Kim,D.K.et al .Spinel LiMn 2O 4nanorods as lithium ion battery cathodes.NanoLett.8,3948–3952(2008).19.Be´langer,D.,Brousse,T.&Long,J.W.Manganese oxides:battery materials make the leap to electrochemical capacitors.Electrochem.Soc.Interf.17,49–52(2008).20.Decher,G.Fuzzy nanoassemblies:toward layered polymeric multicomposites.Science 277,1232–1237(1997).21.Xiang,H.F.et al .Effect of capacity matchup in the LiNi 0.5Mn 1.5O 4/Li 4Ti 5O 12cells.J.Power Sources 183,355–360(2008).22.Dudney,J.N.Thin ﬁlm micro-batteries.Electrochem.Soc.Interf.17,44–48(2008).23.Lee,Seung Woo et al .Layer-by-layer assembly of all carbon nanotube ultrathinﬁlms for electrochemical applications.J.Am.Chem.Soc.131,671–679(2009).24.Niu,C.M.et al .High power electrochemical capacitors based on carbonnanotube electrodes.Appl.Phys.Lett.70,1480–1482(1997).25.Futaba,D.N.et al .Shape-engineerable and highly densely packed single-walledcarbon nanotubes and their application as super-capacitor electrodes.Nature Mater.5,987–994(2006).26.Zielke,U.,Huttinger,K.J.&Hoffman,W.P.Surface-oxidized carbon ﬁbers:I.Surface structure and chemistry.Carbon 34,983–998(1996).27.Kozlowski,C.&Sherwood,P.M.A.X-ray photoelectron-spectroscopic studiesof carbon-ﬁbre surfaces.Part 5.The effect of pH on surface oxidation.J.Chem.Soc.Farad.Trans.I 81,2745–2756(1985).28.Frackowiak,E.et al .Electrochemical storage of lithium multiwalled carbonnanotubes.Carbon 37,61–69(1999).29.Zhu,X.Y.,Lee,S.M.,Lee,Y.H.&Frauenheim,T.Adsorption and desorption ofan O 2molecule on carbon nanotubes.Phys.Rev.Lett.85,2757–2760(2000).30.Burg,P.et al .The characterization of nitrogen-enriched activated carbons by IR,XPS and LSER methods.Carbon 40,1521–1531(2002).Surface functional groups:Faradaic RXN centresOOLi Li Li+OO Figure 5|Schematic of the energy storage mechanism of LBL-MWNT electrodes.Faradaic reactions between surface oxygen functional species (orange arrows)and Li schematically illustrated on an HRTEM image of the LBL-MWNT electrodes.Intact graphite layers inside the MWNT s (white arrows)are indicated as electron conduction channels.DOI:10.1038/NNANO.2010.116。

Metal Corrosion

[4] Corrosion on Plasma Etched Metal Lithography from Processing and Environmental Factors. K.E.Mautts, Electrochemical Society Proceedings, Vol. 97-31, page 240, 1997. [5] Characterization of Metal Pattern Density and Metal Stack Composition on Chlorine Residues from Metal Etch Process. S. Y. Loong et al, SPIE Conference on Multilevel Interconnect T[6e]cPhrneovleongtyio, nVolf. C35o0rr8o,sSioannDtaaCmlagrae, ACfafelicfotirnngiaP. lSaespmteamEbtcehre1d99A8l .Alloy Lithography. G. Gebara et al. Proceedings of the 10th Symposium on Plasma Processing. Dielectric Science and Technology and E[7l]eRcterodnuictiDoniviosfioCno, rVroosl.io9n4-D2e0f,epcatsgeon42M1e,t1a9l 9A4ll.oy Interconnections. G. Gebara and K. Mautz, VMIC Conference, page 326, June 1993.
光罩透射率对铝金属蚀刻腐蚀缺陷的影响铝金属蚀刻工艺中最重要的缺陷是作铝者金：属姚残涛锋留，和上铝海金交属通大腐学蚀微。电铝子学金院属残留往往取决蚀刻腔体的环境，而铝金属腐蚀往往要复杂的多，而造成起复杂性的一个重要原因就是在干法蚀刻工艺（主蚀刻步骤，图1）中，它是一个使用氯等离子体的金属蚀刻工艺 (参见公式1) 。 Al + Cl2 => AlCl3 (可挥发性,主蚀刻气体) (1) BCl3=> BCl3+ + BClx(轰击) (2) BClx + Cl => BClx+1 (消耗侧壁上的氯) (3) CHF3 /CH4 =>生成聚合物层保护侧壁 (4)

LUBRICANT COMPOSITION FOR METAL WORKING

专利名称：LUBRICANT COMPOSITION FOR METAL WORKING发明人：SAWANO HIROYUKI申请号：JP10466584申请日：19840525公开号：JPH0221435B2公开日：19900514专利内容由知识产权出版社提供摘要：PURPOSE:The titled compsn. with excellent lubricity, rustproofness and degreasing ability, comprising a polyacrylic resin (alkali metal salt), a specified alkaline earth metal compd., and an aliph. sulfonic acid alkali (alkaline earth) metal salt or an amine. CONSTITUTION:100pts.wt. polyacrylic resin (alkali metal salt) of formula I (wherein R<1> is H or 1-4C alkyl; R<2> is H, 1-8C alkyl or alkali metal such as Na or K) having MW of 20,000-60,000, is compounded with 0.1-10pts.wt. at least one alkaline earth metal compd. selected from among an alkaline earth metal salt of a saturated fatty acid of formula II (wherein R<3> is 9-33C alkyl; M is alkaline earth metal), an alkali (alkaline earth) metal acrylate and an inorg. alkaline earth metal compd. such as CaCO3 and 1-20pts.wt. at least one compd. selected from among an alkali (alkaline earth) metal salt of an aliph. sulfonic acid of formula III (wherein R<4> is 1-40C alkyl) and an amine such as triethanolamine, and diluted in water.申请人：IDEMITSU KOSAN CO更多信息请下载全文后查看。

硅氧烷化合物的合成与应用进展

材料工程Journal of Materials Engineering第4 9卷第4期2021年4月第13-22页Vol. 4 9 No. 4Apr. 2021 pp. 13 — 22硅氧烷化合物的合成与应用进展Research progress in synthesis andapplication of siloxane compounds程玉桥，路双，冯喆，赵文辉，张治婷，赵越(天津工业大学化学与化工学院，天津300387)CHENG Yu-qiao ,T/U Shuang ,FENG Zhe,ZHAO Wen-hui ,ZHANG Zhi-t.ing,ZHAO Yue(School of Chemistry and Chemical Engineering ,TiangongUniversity? Tianjin 300387 , China)摘要：基于硅氧键特点以及不同条件的化学反应是构建结构迥异、性能独特的新型有机/无机硅氧功能材料的重要方法，近年来，引起了学术界的普遍关注。

新型硅氧功能材料兼具有机/无机化合物性质，以其良好的生物相容性、耐高低温性以及电绝缘性能被广泛应用于众多领域。

本文综述了硅氧烷化合物设计、合成与应用的研究领域及发展现状，重点介绍线性结构(一维结构)、非线性结构(二维结构)、多面体低聚倍半硅氧烷化合物(三维结构)以及有机/无机杂化硅氧烷化合物的设计及合成方法，并通过研究可拉伸聚硅氧烷弹性体、硅氧烷化合物涂层、新型驱油用硅氧功能材料等多种方式以增进硅氧烷化合物在生物医学、航空航天、功能材料及三次采油方面的应用进展。

关键词：线性结构；非线性结构；多面体低聚倍半硅氧烷；有机/无机杂化硅氧烷化合物；合成方法doi ： 10. 11868/. issn. 1001-4381.2020. 000125中图分类号：O613.72文献标识码：A 文章编号：10014381(2021)04-0013-10Abstract ： Chemical reactions based on the characteristics of silicon-oxygen bonds and differentconditions are important methods to construct new organic/inorganic siloxane functional materialswith very different structures and unique properties , which have aroused widespread attention in the academic community. The new silicon-oxygen functional materials have both organic/inorganic compound properties , and are widely used in many fields for their good biocompatibility , high and lowtemperature resistance , and electrical insulation properties. The research fields and developmentstatus of the design , synthesis and application of siloxane compounds were reviewed in this paper , focusing on the design and synthesis methods of linear structure (one-dimensional structure ),nonlinear structure (t.wo-climensional structure ) , polyhedral oligomeric silsesquioxane compounds (three-dimensional structure) and organic/inorganic hybrid siloxane compounds , and the application progress of siloxane compounds in biomedicine , aerospace , functional materials and tertiary oilrecovery will be promoted by studying stretchable polysiloxane elastomer , siloxane compound coating , new silicone functional materials for oil displacement and so on.Key words : linear structure ； nonlinear structure ； polyhedral oligomeric silsesquioxane ； organic/inorganic hybrid siloxane compounds ;synthesis method随着材料科学的不断发展，硅氧烷化合物因其良好的耐热性、生物相容性、高透气性和高绝缘性能在诸多领域占据着重要地位。

光催化中表面等离子体与半导体间的电子转移与能量转移

光催化中表面等离子体与半导体间的电子转移与能量转移吴世康【摘要】近年来,表面等离子诱导的光催化反应由于可在阳光激发下通过电子转移、电荷分离进行选择性光氧化还原反应,引起了有机化学与环境科学界的广泛关注.本文在近年有关文献的基础上对等离子光催化领域一些基础性问题进行探讨,如贵金属-纳米颗粒的可见光激发、LSPR的生成、贵金属与半导体材料间的电子转移、贵金属纳米颗粒与半导体间的等离子诱导共振能量转移(PIRET),以及等离子光催化体系的结构和组成等,这些方面对体系光催化能力的影响.%Recently,the plasmon-induced surface photo-catalytic reaction attracts more and more attention in the area of organic chemistry and the environmental sciences,because it can improve the photo-oxidation and reduction andthe selectivity of reaction by electron-transfer and energy-transfer processes under excitation of sun-light.Some fundamental problems in the field of plasmon photo-catalyst have been discussed in this paper on the base of the recent international literatures.The discussed topics include:the LSPR formation under excitation of noble-metallic nano-particles by visible light and the electron-transfer between noble-metal and semi-conductor;the plasmon induced resonance energy transfer (PIRET) between plasmon particle and semiconductor;and the effect of structure and components of plasmon catalyst on the catalytic ability of catalysts.【期刊名称】《影像科学与光化学》【年(卷),期】2018(036)001【总页数】13页(P1-13)【关键词】局域的等离子共振(LSPR);等离子光催化;电子转移;等离子诱导的共振能量转移(PIRET);二氧化钛【作者】吴世康【作者单位】中国科学院理化技术研究所,北京100190【正文语种】中文纳米尺寸的等离子体可特征性地导致入射光的局域和浓缩，从而形成一类新型的光源、热源、载流子源等，这种特征使近年来对等离子的研究取得了巨大的进展[1]。

211050371_正负压一体式无空气X_射线光电子能谱原位转移仓的开发及研制

第 29 卷第 1 期分析测试技术与仪器Volume 29 Number 1 2023年3月ANALYSIS AND TESTING TECHNOLOGY AND INSTRUMENTS Mar. 2023大型仪器功能开发(30 ~ 36)正负压一体式无空气X射线光电子能谱原位转移仓的开发及研制章小余，赵志娟，袁　震，刘　芬（中国科学院化学研究所，北京　100190）摘要：针对空气敏感材料的表面分析，为了获得更加真实的表面组成与结构信息，需要提供一个可以保护样品从制备完成到分析表征过程中不接触大气环境的装置. 通过使用O圈密封和单向密封柱，提出一种简便且有效的设计概念，自主研制了正负压一体式无空气X射线光电子能谱（XPS）原位转移仓，用于空气敏感材料的XPS测试，利用单向密封柱实现不同工作需求下正负压两种模式的任意切换. 通过对空气敏感的金属Li片和CuCl粉末进行XPS分析表明，采用XPS原位转移仓正压和负压模式均可有效避免样品表面接触空气，保证测试结果准确可靠，而且采用正压密封方式转移样品可以提供更长的密封时效性. 研制的原位转移仓具有设计小巧、操作简便、成本低、密封效果好的特点，适合给有需求的用户开放使用.关键词：空气敏感；X射线光电子能谱；原位转移；正负压一体式中图分类号：O657; O641; TH842 文献标志码：B 文章编号：1006-3757（2023）01-0030-07 DOI：10.16495/j.1006-3757.2023.01.005Development and Research of Inert-Gas/Vacuum Sealing Air-Free In-Situ Transfer Module of X-Ray Photoelectron SpectroscopyZHANG Xiaoyu， ZHAO Zhijuan， YUAN Zhen， LIU Fen（Institute of Chemistry Chinese Academy of Sciences, Beijing 100190, China）Abstract：For the surface analysis of air sensitive materials, and from the sample preparation to characterization, it is necessary to provide a device that can protect samples from exposing to the atmosphere environment so as to obtain accurate and impactful data of the surface chemistry. Through the use of O-ring and one-way sealing, a simple and effective design concept has been demonstrated, and an inert-gas/vacuum sealing air-free X-ray photoelectron spectroscopic (XPS) in-situ transfer module has been developed to realize the XPS analysis of air sensitive materials. The design of one-way sealing was achieved conveniently by switching between inert-gas and vacuum sealing modes in face of different working requirements. The XPS analysis of air-sensitive metal Li sheets and CuCl powders showed that both the sealing modes (an inert-gas/vacuum sealing) of the XPS in-situ transfer module can effectively avoid air contact on the sample surface, and consequently, can ensure the accuracy and reliability of XPS data. Furthmore, the inert gas sealing mode can keep the sample air-free for a longer time. The homemade XPS in-situ transfer module in this work is characterized by a compact design, convenient operation, low cost and effective sealing, which is suitable for the open access to the users who need it.收稿日期：2022−12−07；　修订日期：2023−01−17.基金项目：中国科学院化学研究所仪器孵化项目[Instrument and Device Functional Developing Project of Institute of Chemistry Chinese Academy of Sciences]作者简介：章小余（1986−），女，硕士，工程师，主要研究方向为电子能谱技术及材料表面分析，E-mail：xyiuzhang@ .Key words：air-sensitive；X-ray photoelectron spectroscopy；in-situ transfer；inert-gas/vacuum sealingX射线光电子能谱（XPS）是一种表面灵敏的分析技术，通常用于固体材料表面元素组成和化学态分析[1]. 作为表面分析领域中最有效的方法之一，XPS广泛应用于纳米科学、微电子学、吸附与催化、环境科学、半导体、冶金和材料科学、能源电池及生物医学等诸多领域[2-3]. 其中在催化和能源电池材料分析中，有一些样品比较特殊，比如碱金属电池[4-6]、负载型纳米金属催化剂[7-8]和钙钛矿材料[9]对空气非常敏感，其表面形态和化学组成接触空气后会迅速发生改变，直接影响采集数据的准确性和有效性，因此这类样品的表面分析测试具有一定难度. 目前，常规的光电子能谱仪制样转移过程通常是在大气环境中，将样品固定在标准样品台上，随后放入仪器进样室内抽真空至1×10−6 Pa，再转入分析室内进行测试. 这种制备和进样方式无法避免样品接触大气环境，对于空气敏感材料，其表面很容易与水、氧发生化学反应，导致无法获得材料表面真实的结构信息.为了保证样品表面状态在转移至能谱仪内的过程中不受大气环境影响，研究人员采用了各种技术来保持样品转移过程中隔绝空气. 比如前处理及反应装置与电子能谱仪腔室间真空传输[10-12]、外接手套箱 [13-14]、商用转移仓[15-16]、真空蒸镀惰性金属比如Al层（1.5~6 nm）[17]等. 尽管上述技术手段有效，但也存在一些缺点，例如配套装置体积巨大、试验过程不易操作、投入成本高等，这都不利于在普通实验室内广泛应用. 而一些电子能谱仪器制造商根据自身仪器的特点也研发出了相应配套的商用真空传递仓，例如Thermofisher公司研发的一种XPS 真空转移仓，转移过程中样品处于微正压密封状态，但其价格昂贵，体积较大，转移过程必须通过手套箱大过渡舱辅助，导致传递效率低，单次需消耗至少10 L高纯氩气，因此购置使用者较少，利用率低.另外有一些国内公司也研发了类似的商品化气体保护原位传递仓，采用微正压方式密封转移样品，但需要在能谱仪器进样室舱门的法兰上外接磁耦合机械旋转推拉杆，其操作复杂且放置样品的有效区域小，单次仅可放置尺寸为3 mm×3 mm的样品3～4个，进样和测试效率较低. 因此，从2016年起本实验团队开始自主研制XPS原位样品转移装置[18]，经过结构与性能的迭代优化[19]，最终研制出一种正负压一体式无空气XPS原位转移仓[20]（本文简称XPS原位转移仓），具有结构小巧、操作便捷、成本低、密封效果好、正压和负压密封两种模式转移样品的特点. 为验证装置的密封时效性能，本工作选取两种典型的空气敏感材料进行测试，一种是金属Li材料，其化学性质非常活泼，遇空气后表面迅速与空气中的O2、N2、S等反应导致表面化学状态改变. 另一种是无水CuCl粉末，其在空气中放置短时间内易发生水解和氧化. 试验结果表明，该XPS 原位转移仓对不同类型的空气敏感样品的无空气转移均可以提供更便捷有效的密封保护. 目前，XPS原位转移仓已在多个科研单位的实验室推广使用，支撑应用涉及吸附与催化、能源环境等研究领域.1　试验部分1.1　XPS原位转移仓的研制基于本实验室ESCALAB 250Xi型多功能光电子能谱仪器（Thermofisher 公司）的特点，研究人员设计了XPS原位转移仓. 为兼顾各个部件强度、精度与轻量化的要求，所有部件均采用钛合金材料.该装置从整体结构上分为样品台、密封罩和紧固挡板三个部件，如图1（a）~（c）所示. 在密封罩内部通过单向密封设计[图1（e）]使得XPS原位转移仓实现正负压一体，实际操作中可通过调节密封罩上的螺帽完成两种模式任意切换. 同时，从图1（e）中可以直观看到，密封罩与样品台之间通过O圈密封，利用带有螺钉的紧固挡板将二者紧密固定. 此外，为确保样品台与密封罩对接方位正确，本设计使用定向槽定位样品台与密封罩位置，保证XPS原位转移仓顺利传接到仪器进样室.XPS原位转移仓使用的具体流程：在手套箱中将空气敏感样品粘贴至样品台上，利用紧固挡板使样品台和密封罩固定在一起，通过调节密封罩上的螺帽将样品所在区域密封为正压惰性气氛（压强为300 Pa、环境气氛与手套箱内相同）或者负压真空状态，其整体装配实物图如图1（d）所示. 该转移仓结构小巧，整体尺寸仅52 mm×58 mm×60 mm，可直接放入手套箱小过渡舱传递. 由于转移仓尺寸小，其第 1 期章小余，等：正负压一体式无空气X射线光电子能谱原位转移仓的开发及研制31原料成本大大缩减，整体造价不高. 转移仓送至能谱仪进样室后，配合样品停放台与进样杆的同时双向对接，将转移仓整体固定在进样室内，如图1（f ）所示. 此时关闭进样室舱门开始抽真空，当样品台与密封罩内外压强平衡后密封罩自动解除真空密封，但仍然处于O 圈密闭状态. 等待进样室真空抽至1×10−4Pa 后，使用能谱仪进样室的样品停放台摘除脱离的密封罩[如图1（g ）所示]，待真空抽至1×10−6Pa ，即可将样品送入分析室进行XPS 测试.整个试验过程操作便捷，实现了样品从手套箱转移至能谱仪内不接触大气环境.1.2　试验过程1.2.1　样品准备及转移试验所用手套箱是布劳恩惰性气体系统（上海）有限公司生产，型号为MB200MOD （1500/780）NAC ；金属Li 片购自中能锂业，纯度99.9%；CuCl 购自ALFA 公司，纯度99.999%.金属Li 片的制备及转移：将XPS 原位转移仓整体通过手套箱过渡舱送入手套箱中，剪取金属Li 片用双面胶带固定于样品台上，分别采用正压、负压两种密封模式将XPS 原位转移仓整体从手套箱中取出，分别在空气中放置0、2、4、8、18、24、48、72 h 后送入能谱仪内，进行XPS 测试.CuCl 粉末的制备及转移：在手套箱中将CuCl 粉末压片[21]，使用上述同样的制备方法，将XPS 原位转移仓整体在空气中分别放置0、7、24、72 h 后送入能谱仪内，进行XPS 测试.1.2.2　样品转移方式介绍样品在手套箱中粘贴完成后，分别采用三种方式将其送入能谱仪. 第一种方式是在手套箱内使用标准样品台粘贴样品，将其装入自封袋密封，待能谱仪进样室舱门打开后，即刻打开封口袋送入仪器中开始抽真空等待测试，整个转移过程中样品暴露空气约15 s. 第二种方式是使用XPS 原位转移仓负压密封模式转移样品，具体操作步骤：利用紧固挡板将样品台和密封罩固定在一起，逆时针（OPEN ）旋动螺帽至顶部，放入手套箱过渡舱并将其抽为真空，此过程中样品所在区域也抽至负压. 取出整体装置后再顺时针（CLOSE ）旋动螺帽至底部，将样品所在区域进一步锁死密封. 样品在负压环境中转移至XPS 实验室，拆卸掉紧固挡板，随即送入能谱仪进样室内. 第三种方式是使用XPS 原位转移仓正压密封模式转移样品，具体操作步骤：利用紧固挡板将样品台和密封罩固定在一起，顺时针（CLOSE ）旋螺帽抽气管限位板单向密封柱密封罩主体O 圈样品台紧固挡板(e) 密封罩对接停放台机械手样品台对接进样杆(a)(b)(c)(d)(g)图1　正负压一体式无空气XPS 原位转移仓系统装置（a ）样品台，（b ）密封罩，（c ）紧固挡板，（d ）整体装配实物图，（e ）整体装置分解示意图，（f ）样品台与密封罩在进样室内对接完成，（g ）样品台与密封罩在进样室内分离Fig. 1　System device of inert-gas/vacuum sealing air-free XPS in-situ transfer module32分析测试技术与仪器第 29 卷动螺帽至底部，此时样品所在区域密封为正压惰性气氛. 直至样品转移至XPS 实验室，再使用配套真空抽气系统（如图2所示），通过抽气管将样品所在区域迅速抽为负压，拆卸掉紧固挡板，随即送入能谱仪进样室内.图2　能谱仪实验室内配套真空抽气系统Fig. 2　Vacuum pumping system in XPSlaboratory1.2.3　XPS 分析测试试验所用仪器为Thermo Fisher Scientific 公司的ESCALAB 250Xi 型多功能X 射线光电子能谱仪，仪器分析室基础真空为1×10−7Pa ，X 射线激发源为单色化Al 靶（Alk α，1 486.6 eV ），功率150 W ，高分辨谱图在30 eV 的通能及0.05 eV 的步长等测试条件下获得，并以烃类碳C 1s 为284.8 eV 的结合能为能量标准进行荷电校正.2　结果与讨论2.1　测试结果分析为了验证XPS 原位转移仓的密封性能，本文做了一系列的对照试验，选取空气敏感的金属Li 片和CuCl 粉末样品进行XPS 测试，分别采用上述三种方式转移样品，并考察了XPS 原位转移仓密封状态下在空气中放置不同时间后对样品测试结果的影响.2.1.1　负压密封模式下XPS 原位转移仓对金属Li片的密封时效性验证将金属Li 片通过两种（标准和负压密封）方式转移并在空气中放置不同时间，对这一系列样品进行XPS 测试，Li 1s 和C 1s 高分辨谱图结果如图3（a ）（b ）所示，试验所测得的Li 1s 半峰宽值如表1所列. 根据XPS 结果分析，金属Li 片采用标准样品台进样（封口袋密封），短暂暴露空气约15 s ，此时Li 1s 的半峰宽为1.62 eV. 而采用XPS 原位转移仓负压密封模式转移样品时，装置整体放置空气18 h 内，Li 1s 的半峰宽基本保持为（1.35±0.03） eV. 放置空气24 h 后，Li 1s 的半峰宽增加到与暴露空气15 s 的金属Li 片一样，说明此时原位转移仓的密封性能衰减，金属Li 片与渗入内部的空气发生反应生成新物质导致Li 1s 半峰宽变宽. 由图3（b ）中C 1s 高分辨谱图分析，结合能位于284.82 eV 的峰归属为C-C/污染C ，位于286.23 eV 的峰归属为C-OH/C-O-CBinding energy/eVI n t e n s i t y /a .u .Li 1s半峰宽增大暴露 15 s密封放置 24 h 密封放置 18 h 密封放置 8 h 密封放置 4 h 密封放置 0 h6058565452Binding energy/eVI n t e n s i t y /a .u .C 1s(a)(b)暴露 1 min 暴露 15 s 密封放置 24 h 密封放置 18 h 密封放置 0 h292290288284282286280图3　金属Li 片通过两种（标准和负压密封）方式转移并在空气中放置不同时间的（a ）Li 1s 和（b ）C 1s 高分辨谱图Fig. 3　High-resolution spectra of (a) Li 1s and (b) C 1s of Li sheet samples transferred by two methods (standard andvacuum sealings) and placed in air for different times第 1 期章小余，等：正负压一体式无空气X 射线光电子能谱原位转移仓的开发及研制33键，位于288.61~289.72 eV的峰归属为HCO3−/CO32−中的C[22]. 我们从C 1s的XPS谱图可以直观的看到，与空气短暂接触后，样品表面瞬间生成新的结构，随着暴露时间增加到1 min，副反应产物大量增加（HCO3−/CO32−）. 而XPS原位转移仓负压密封模式下在空气中放置18 h内，C结构基本不变，在空气中放置24 h后，C结构只有微小变化. 因此根据试验结果分析，对于空气极其敏感的材料，在负压密封模式下，建议XPS原位转移仓在空气中放置时间不要超过18 h. 这种模式适合对空气极其敏感样品的短距离转移.表 1 通过两种（标准和负压密封）方式转移并在空气中放置不同时间的Li 1s的半峰宽Table 1　Full width at half maxima (FWHM) of Li 1stransferred by two methods (standard and vacuum sealings) and placed in air for different times样品说明进样方式半峰宽/eV密封放置0 h XPS原位转移仓负压密封模式转移1.38密封放置2 h同上 1.39密封放置4 h同上 1.36密封放置8 h同上 1.32密封放置18 h同上 1.32密封放置24 h同上 1.62暴露15 s标准样品台进样（封口袋密封）1.622.1.2　正压密封模式下原位转移仓对金属Li片的密封时效性验证将金属Li片通过两种（标准和正压密封）方式转移并在空气中放置不同时间，对这一系列样品进行XPS测试，Li 1s高分辨谱图结果如图4所示，所测得的Li 1s半峰宽值如表2所列. 根据XPS结果分析，XPS原位转移仓正压密封后，在空气中放置72 h内，Li 1s半峰宽基本保持为（1.38±0.04） eV，说明有明显的密封效果，金属Li片仍然保持原有化学状态. 所以对于空气极其敏感的材料，在正压密封模式下，可至少在72 h内保持样品表面不发生化学态变化. 这种模式适合长时间远距离（可全国范围内）转移空气敏感样品.2.1.3　负压密封模式下XPS原位转移仓对空气敏感样品CuCl的密封时效性验证除了金属Li片样品，本文还继续考察XPS原位转移仓对空气敏感样品CuCl的密封时效性. 图5为CuCl粉末通过两种（标准和负压密封）方式转移并在空气中放置不同时间的Cu 2p高分辨谱图. XPS谱图中结合能[22]位于932.32 eV的峰归属为Cu+的Cu 2p3/2，位于935.25 eV的峰归属为Cu2+的Cu 2p3/2，此外，XPS谱图中位于940.00~947.50 eV 处的峰为Cu2+的震激伴峰，这些震激伴峰被认为是表 2 通过两种（标准和正压密封）方式转移并在空气中放置不同时间的Li 1s的半峰宽Table 2　FWHM of Li 1s transferred by two methods(standard and inert gas sealings) and placed in air fordifferent times样品说明进样方式半峰宽/eV 密封放置0 h XPS原位转移仓正压密封模式转移1.42密封放置2 h同上 1.35密封放置4 h同上 1.35密封放置8 h同上 1.34密封放置18 h同上 1.38密封放置24 h同上 1.39密封放置48 h同上 1.42密封放置72 h同上 1.38暴露15 s标准样品台进样（封口袋密封）1.62Binding energy/eVIntensity/a.u.Li 1s半峰宽比正压密封的宽半峰宽=1.62 eV半峰宽=1.38 eV暴露 15 s密封放置 72 h密封放置 48 h密封放置 24 h密封放置 18 h密封放置 0 h605856545250图4　金属Li片通过两种（标准和正压密封）方式转移并在空气中放置不同时间的Li 1s高分辨谱图Fig. 4　High-resolution spectra of Li 1s on Li sheet samples transferred by two methods (standard and inert gas sealings) and placed in air for different times34分析测试技术与仪器第 29 卷价壳层电子向激发态跃迁的终态效应所产生[23]，而在Cu +和Cu 0中则观察不到.根据XPS 结果分析，CuCl 在XPS 原位转移仓保护（负压密封）下，即使放置空气中72 h ，测得的Cu 2p 高分辨能谱图显示只有Cu +存在，说明CuCl 并未被氧化. 若无XPS 原位转移仓保护，CuCl 粉末放置空气中3 min 就发生了比较明显的氧化，从测得的Cu 2p 高分辨能谱图能够直观的看到Cu 2+及其震激伴峰的存在，并且随着放置时间增加到40 min ，其氧化程度也大大增加. 因此，对于空气敏感的无机材料、纳米催化剂和钙钛矿材料等，采用负压密封模式转移就可至少在72 h 内保持样品表面不发生化学态变化.3　结论本工作中自主研制的正负压一体式无空气XPS原位转移仓在空气敏感样品转移过程中可以有效隔绝空气，从而获得样品最真实的表面化学结构.试验者可根据样品情况和实验室条件选择转移模式，并在密封有效时间内将样品从实验室转移至能谱仪中完成测试. 综上所述，该XPS 原位转移仓是一种设计小巧、操作简便、密封性能优异、成本较低的样品无水无氧转移装置，因此非常适合广泛开放给有需求的试验者使用. 在原位和准原位表征技术被广泛用于助力新材料发展的现阶段，希望该设计理念能对仪器功能的开发和更多准原位表征测试的扩展提供一些启示.参考文献：黄惠忠. 论表面分析及其在材料研究中的应用[M ].北京: 科学技术文献出版社, 2002: 16-18.［ 1 ］杨文超, 刘殿方, 高欣, 等. X 射线光电子能谱应用综述[J ]. 中国口岸科学技术，2022，4（2）：30-37.[YANG Wenchao, LIU Dianfang, GAO Xin, et al.TheapplicationofX -rayphotoelectronspectroscopy [J ]. China Port Science and Technology ，2022，4 （2）：30-37.]［ 2 ］郭沁林. X 射线光电子能谱[J ]. 物理，2007，36（5）：405-410. [GUO Qinlin. X -ray photoelectron spectro-scopy [J ]. Physics ，2007，36 （5）：405-410.]［ 3 ］Malmgren S, Ciosek K, Lindblad R, et al. Con-sequences of air exposure on the lithiated graphite SEI [J ]. Electrochimica Acta ，2013，105 ：83-91.［ 4 ］Zhang Y H, Chen S M, Chen Y, et al. Functional poly-ethylene glycol-based solid electrolytes with enhanced interfacial compatibility for room-temperature lithium metal batteries [J ]. Materials Chemistry Frontiers ，2021，5 （9）：3681-3691.［ 5 ］周逸凡, 杨慕紫, 佘峰权, 等. X 射线光电子能谱在固态锂离子电池界面研究中的应用[J ]. 物理学报，2021，70（17）：178801. [ZHOU Yifan, YANG Muzi,SHE Fengquan, et al. Application of X -ray photoelec-tron spectroscopy to study interfaces for solid-state lithium ion battery [J ]. Acta Physica Sinica ，2021，70（17）：178801.]［ 6 ］Huang J J, Song Y Y, Ma D D, et al. The effect of thesupport on the surface composition of PtCu alloy nanocatalysts: in situ XPS and HS-LEIS studies [J ].Chinese Journal of Catalysis ，2017，38 （7）：1229-1236.［ 7 ］Koley P, Shit S C, Sabri Y M, et al. Looking into moreeyes combining in situ spectroscopy in catalytic bio-fuel upgradation with composition-graded Ag-Co core-shell nanoalloys [J ]. ACS Sustainable Chemistry &Engineering ，2021，9 （10）：3750-3767.［ 8 ］Opitz A K, Nenning A, Rameshan C, et al. Enhancingelectrochemical water-splitting kinetics by polarization-driven formation of near-surface iron(0): an in situ XPS study on perovskite-type electrodes [J ]. Ange-wandte Chemie (International Ed in English)，2015，54（9）：2628-2632.［ 9 ］Czekaj I, Loviat F, Raimondi F, et al. Characterization［ 10 ］Binding energy/eVI n t e n s i t y /a .u .Cu 2pCu +Cu 2+暴露 3 min暴露 40 min 密封放置 7 h 密封放置 72 h 密封放置 24 h密封放置 0 h960950945935925955940930920图5　CuCl 粉末通过两种（标准和负压密封）方式转移并在空气中放置不同时间的Cu 2p 高分辨谱图Fig. 5　High-resolution spectra of Cu 2p on CuCl powder samples transferred by two methods (standard and vacuumsealings) and placed in air for different times第 1 期章小余，等：正负压一体式无空气X 射线光电子能谱原位转移仓的开发及研制35of surface processes at the Ni-based catalyst during the methanation of biomass-derived synthesis gas: X -ray photoelectron spectroscopy (XPS)[J ]. Applied Cata-lysis A:General ，2007，329 ：68-78.Rutkowski M M, McNicholas K M, Zeng Z Q, et al.Design of an ultrahigh vacuum transfer mechanism to interconnect an oxide molecular beam epitaxy growth chamber and an X -ray photoemission spectroscopy analysis system [J ]. Review of Scientific Instruments ，2013，84 （6）：065105.［ 11 ］伊晓东, 郭建平, 孙海珍, 等. X 射线光电子能谱仪样品前处理装置的设计及应用[J ]. 分析仪器，2008（5）：8-11. [YI Xiaodong, GUO Jianping, SUN Haizhen, et al. Design of a sample pretreatment device for X -ray photoelectron spectrometer [J ]. Analytical Instrumentation ，2008 （5）：8-11.]［ 12 ］Aurbach D, Weissman I, Schechter A, et al. X -ray pho-toelectron spectroscopy studies of lithium surfaces pre-pared in several important electrolyte solutions. A comparison with previous studies by Fourier trans-form infrared spectroscopy [J ]. Langmuir ，1996，12（16）：3991-4007.［ 13 ］Światowska-Mrowiecka J, Maurice V, Zanna S, et al.XPS study of Li ion intercalation in V 2O 5 thin films prepared by thermal oxidation of vanadium metal [J ].Electrochimica Acta ，2007，52 （18）：5644-5653.［ 14 ］Weingarth D, Foelske-Schmitz A, Wokaun A, et al. Insitu electrochemical XPS study of the Pt/[BF 4]system [J ]. Electrochemistry Communications ，2011，13 （6）：619-622.［ 15 ］Schneider J D, Agocs D B, Prieto A L. Design of asample transfer holder to enable air-free X -ray photo-electron spectroscopy [J ]. Chemistry of Materials ，2020，32 （19）：8091-8096.［ 16 ］Karamurzov B S, Kochur A G, Misakova L B, et al.Calculation of the pure surface composition of the bin-ary alloy according to XPS data obtained after the al-loy surface contact with air [J ]. Journal of Structural Chemistry ，2015，56 （3）：576-581.［ 17 ］章小余, 赵志娟. 一种半原位XPS 样品转移装置: 中国, 201620925237.5[P ]. 2017-02-15.［ 18 ］章小余, 袁震, 赵志娟. 一种半原位X 射线光电子能谱分析仪的样品转移装置: 中国, 201720056623.X [P ]. 2017-12-08.［ 19 ］袁震, 章小余, 赵志娟. 一种样品转移装置及转移方法: 中国, 2011203822.1[P ]. 2022-03-01.［ 20 ］刘芬, 赵志娟, 邱丽美, 等. XPS 分析固体粉末时的样品制备法研究[J ]. 分析测试技术与仪器，2007，13（2）：107-109. [LIU Fen, ZHAO Zhijuan, QIU Limei, et al. Study of sample preparation method for XPS analysis of powdered samples [J ]. Analysis and Testing Technology and Instruments ，2007，13 （2）：107-109.]［ 21 ］Wagner C D, Riggs W M, Davis L E, et al. Handbookof X -ray photoelectron spectroscopy [M ]. Eden Prair-ie, Minnesota, 1978.［ 22 ］Watts J F, Wolstenholme J. 表面分析(XPS 和AES)引论[M ]. 吴正龙, 译. 上海: 华东理工大学出版社,2008.［ 23 ］36分析测试技术与仪器第 29 卷。

新型金属硫化物二维半导体材料性质探明

新型金属硫化物二维半导体材料性质探明
佚名
【期刊名称】《分析测试学报》
【年(卷),期】2014(33)4
【摘要】中国科学院半导体研究所超晶格国家重点实验室博士后杨圣雪、博士生
李燕，在研究员李京波、中科院院士李树深和夏建白等人的指导下，取得二维GaS超薄半导体基础研究的新进展，探明了新型超薄金属硫化物二维半导体材料
性质。

相关成果发表在英国皇家化学会主办的《纳米尺度》上，并被选为热点论文。

【总页数】1页(P448-448)
【关键词】中国科学院半导体研究所;金属硫化物;材料性质;二维;国家重点实验室;
中科院院士;基础研究;纳米尺度
【正文语种】中文
【中图分类】O614
【相关文献】
1.二维半导体过渡金属硫化物的逻辑集成器件 [J], 李卫胜;周健;王瀚宸;汪树贤;于
志浩;黎松林;施毅;王欣然
2.二维过渡金属硫化物硫化铼材料的表面增强拉曼散射效应 [J],
3.二维过渡金属硫化物二次谐波:材料表征、信号调控及增强 [J], 曾周晓松;王笑;
潘安练
4.中科院探明新型金属硫化物二维半导体材料性质 [J], 无
5.二维过渡金属硫化物热电材料的研究进展 [J], 柏祖志;郭勇;刘聪聪
因版权原因，仅展示原文概要，查看原文内容请购买。

ida金属螯合亲和层析介质

ida金属螯合亲和层析介质引言：ida金属螯合亲和层析介质是一种重要的生物分离技术，广泛应用于生物医学、生物化学和生物工程等领域。

它是通过金属离子与靶分子之间的特异性配位作用，实现对靶分子的高效分离和纯化的方法。

本文将介绍ida金属螯合亲和层析介质的原理、制备方法、应用领域及发展前景。

一、ida金属螯合亲和层析介质的原理ida金属螯合亲和层析介质的原理基于金属离子与靶分子之间的特异性配位作用。

ida（亚铁二胺四乙酸）是一种广泛应用的金属螯合剂，它能够与多种金属离子形成稳定的配合物。

通过将ida固定在载体上，可以构建ida金属螯合亲和层析介质。

二、ida金属螯合亲和层析介质的制备方法制备ida金属螯合亲和层析介质的方法主要包括固定化ida的选择、载体的选择和固定化方法的选择。

固定化ida时，可以选择将ida 直接固定在载体上，也可以选择使用交联剂将ida与载体交联。

常用的载体包括琼脂糖、聚丙烯酰胺凝胶等。

三、ida金属螯合亲和层析介质的应用领域ida金属螯合亲和层析介质在生物医学、生物化学和生物工程等领域有广泛的应用。

在生物医学领域，ida金属螯合亲和层析介质可用于药物分离纯化、疾病诊断和治疗等方面。

在生物化学领域，ida 金属螯合亲和层析介质可用于蛋白质纯化、酶分离和多肽合成等方面。

在生物工程领域，ida金属螯合亲和层析介质可用于基因工程药物的纯化和制备等方面。

四、ida金属螯合亲和层析介质的发展前景ida金属螯合亲和层析介质作为一种高效、选择性的分离技术，具有广阔的发展前景。

随着生物医学和生物工程领域的不断发展，对高纯度生物分子的需求越来越大，ida金属螯合亲和层析介质作为一种有效的分离工具将会得到更广泛的应用。

同时，随着新型材料和新型固定化方法的不断涌现，ida金属螯合亲和层析介质在分离效率和选择性上将会有更大的突破。

结论：ida金属螯合亲和层析介质是一种重要的生物分离技术，通过金属离子与靶分子之间的特异性配位作用，实现对靶分子的高效分离和纯化。

METHYLATION PATTERN ANALYSIS OF HAPLOTYPES IN TISS

专利名称：METHYLATION PATTERN ANALYSIS OFHAPLOTYPES IN TISSUES IN DNA MIXTURE 发明人：LO, Yuk-Ming Dennis,CHAN, KwanChee,CHIU, Rossa Wai Kwun,JIANG,Peiyong,SUN, Kun申请号：CN2016/090642申请日：20160720公开号：WO2017/012544A1公开日：20170126专利内容由知识产权出版社提供摘要：Systems, apparatuses, and method are provided for determining the contributions of different tissues to a biological sample that includes a mixture of cell-free DNA molecules from various tissues types, e.g., as occurs in plasma or serum and other body fluids. Embodiments can analyze the methylation patterns of the DNA mixture (e.g., methylation levels at particular loci) for a particular haplotype and determine fractional contributions of various tissue types to the DNA mixture, e.g., of fetal tissue types or tissue types of specific organs that might have a tumor. Such fractional contributions determined for a haplotype can be used in a variety of ways.申请人：THE CHINESE UNIVERSITY OF HONG KONG地址：Office of Research and Knowledge Transfer Services Room 301, Pi Ch'iu Building, Shatin, New Territories Hong Kong 999077 CN国籍：CN代理人：INSIGHT INTELLECTUAL PROPERTY LIMITED更多信息请下载全文后查看。

2-24 Selective Uranium Extraction from Salt Lake Brine by Amidoximated Saccharomyces cerevisiae

·82·IMP&HIRFL Annual Report20152-24Selective Uranium Extraction from Salt Lake Brine byAmidoximated Saccharomyces cerevisiaeBai Jing,Yin Xiaojie and Qin ZhiUranium concentration in salt lake brines is tens even thousands times higher than seawater,which makes salt lake brine being another ideal resource for uranium.However,the content of salt lake brine is very complicate,a large amount of K,Na,Ca,Mg elements coexisting with uranium.Hence,only sorbent with high uranium selectivity can be well used in uranium extraction from salt lake brine.Fig.1(color online)Uranium sorption from salt lake brine by raw biomass and amidoximated S.cerevisiae.To enhance the selectivity of Saccharomyces cere-visiae for uranium,amidoximation of the biomass was performed.–CN groups wasﬁrstly grafted on the biomass surface by radical induced grafting reaction (PAN-B),followed by converting nitrile(–CN)groups to amidoxime(–C(NH2)NOH)groups through reaction with free hydroxylamine(amidoximation).Amidoxi-mated S.cerevisiae(PAO-B)can be obtained through these two steps.The eﬀect of solution pH,extraction time,initial uranium concentration and ion strength on uranium sorption by amdoximated S.cerevisiae was studied in detail and optimum uranium sorption condi-tion was conﬁrmed.Desorption experiment was alsoperformed and the corresponding results showed that amidoximation did not decrease the uranium sorption capacity of the biomass and the amidoximated S.cerevisiae couldbe used at least three times with little loss of uranium uptake capacity.Trace uranium extraction from real salt lake brine samples were conducted,and75%of uranium in the salt lake brine samples was successful absorbed by amidoximated biomass while hardly any uranium was absorbed by raw biomass(Fig.1).Hence,amidoximation can obviously enhance the uranium selectivity of the biomass and amidoximated S.cerevisiae has the potential to selectively extract traceuranium ions from salt lake brine.2-25Gas-phase Chemistry of Short-lived Re Carbonyl Complexes Part1:Adsorption Enthalpy on Teﬂon SurfaceWang Yang1,Qin Zhi1,Fan Fangli1,Hiromitsu.Haba2,Yukiko.Komori2and Shinya.Yanou2 (1Institute of Modern Physics,Chinese Academy of Sciences,Lanzhou730070,China;2Nishina Center for Accelerator-Based Science,RIKEN,Wako,Saitama351-0198,Japan) In the collaboration of RI Applications Team from RIKEN(Japan)and the Nuclear Chemistry Group from IMP(China),the short-lived Re carbonyl complexes were synthesized and investigated.As the lighter homologs of superheavy element Bh,Re belongs to period6,group7of the periodic table.Short-lived Re isotopes with half-lives of several minutes were produced in the reactions of nat Gd(23Na7+,xn)172−177Re at Nishina center of RIKEN.The nat Gd2O3target with a thickness of340µg·cm−2was prepared by electro deposition onto a2µm Ti foil. The23Na7+ion beam was extracted from RILAC(RIKEN Linear Accelerator).The beam energy was130.6MeV cot. The Gas-ﬁlled Recoil Ion Separator(GARIS)was employed to separate the evaporation residues.A gasﬁlled recoil chamber was installed at the focal plane of GARIS[1].Then,volatile carbonyls were synthesized with short-lived Re isotopes and CO contained gas mixture.Gas-phase chemistry technique was used to measure the adsorption enthalpies of these carbonyls on Teﬂon(FEP)surface[2].Fig.1shows the experimental setups.Fig.2shows typicalγ-spectra measured with three diﬀerent kinds of transport.As a result,Re isotopes and their daughters W isotopes were observed in the charcoal trap when CO gas was added into Ar gas,which could prove that volatile Re carbonyls were synthesized with Re atoms and CO gas.After changing the isothermal temperature from25to–70◦C with10◦a step,breakthrough curves of these carbonyls were measured.Monte Carlo simulation program was used to get their adsorption enthalpies on Teﬂon surface.172,174176Re carbonyls were listed as representative,see Fig.3.。

蓝藻psi三聚体结构

蓝藻psi三聚体结构蓝藻 PSI 三聚体结构光系统 I（PSI）是光合作用中将光能转化为化学能的蛋白质复合物。

蓝藻 PSI 三聚体是 PSI 的一种特定的构型，由三个 PSI 单体组成。

PSI 单体结构每个 PSI 单体由 12 个核心亚基和 120 个辅助亚基组成。

核心亚基形成一个异源三聚体核心，包括 PsaA、PsaB 和 PsaC。

辅助亚基分为：天线蛋白亚基：负责捕获光能反应中心亚基：参与光诱导电荷分离电子传递亚基：参与电子供体和受体之间的电子传递三聚体形成蓝藻 PSI 三聚体是由三个 PSI 单体的自组装形成的。

该组装过程受辅助亚基的相互作用的调节，特别是 PsaJ 和 PsaL 亚基之间的相互作用。

PsaJ 和 PsaL 亚基是两个大型跨膜螺旋蛋白，它们介导 PSI 单体之间的相互作用。

它们形成一个疏水性接口，将三个单体连接在一起。

三聚体的特点与 PSI 单体相比，PSI 三聚体具有以下特点：更大的天线尺寸：三聚体的三个天线蛋白复合物共同形成一个更大的光捕获面积，从而提高了光合效率。

增加的反应中心数量：每个三聚体有三个反应中心，可以同时捕获和转化光能。

更强的稳定性：三聚体结构比单体结构更稳定，因为它有更多的相互作用。

功能作用蓝藻 PSI 三聚体作为光合作用中的主要光捕获和能量转化装置，发挥着以下功能：光能捕获：天线蛋白复合物捕获光能并将其传递到反应中心。

电荷分离：反应中心利用光能将电子从叶绿素分子激发到电子传递链。

电子传递：电子通过电子传递亚基从反应中心传递到最终的电子受体。

质子泵送：PSI 的电子传递链与质子泵送相偶联，这有助于建立跨膜质子梯度。

环境适应蓝藻 PSI 三聚体的结构和功能可以适应不同的环境条件，例如光照强度和营养可用性。

例如，在低光照条件下，蓝藻可以增加PSI 三聚体的数量以捕获更多的光能。

对苯二甲酸锌

Hydrothermal Synthesis and Crystal Structure of a Novel 2-Fold Interpenetrated Framework Based on Tetranuclear Homometallic ClusterRong-Yi Huang ÆXue-Jun Kong ÆGuang-Xiang LiuReceived:15December 2007/Accepted:11January 2008/Published online:5March 2008ÓSpringer Science+Business Media,LLC 2008Abstract A novel 2-fold parallel interpenetrated polymer,Zn 2(OH)(pheno)(p -BDC)1.5ÁH 2O (1)(pheno =phenan-threne-9,10-dione;p -BDC =1,4-benzenedicarboxylate)was prepared by hydrothermal synthesis and characterized by IR spectra,elemental analysis and single crystal X-ray plex 1crystallizes in the orthorhombic space group Pbca and affords a three-dimensional (3D)six-connected a -Po network.Keywords Carboxylate ligand ÁHomometallic complex Áa -Po1IntroductionIn the last decade,the construction by design of metal-organic frameworks (MOFs)using various secondary building units (SBUs)connected through coordination bonds,supramolecular contacts (e.g.,hydrogen bonding,p ÁÁÁp stacking,etc.),or their combination has been an increasingly active research area [1].The design and controlled assembly of coordination polymers based on nano-sized MO(OH)clusters and multi-functional car-boxylates have been extensively developed for their crystallographic and potential applications in catalysis,nonlinear optics,ion exchange,gas storage,magnetism and molecular recognition [2].In most cases,multinu-clear metal cluster SBUs can direct the formation of novel geometry and topology of molecular architectureand help to retain the rigidity of the networks [3].A number of carboxylate-bridged metal clusters have been utilized to build extended coordination frameworks.Among these compounds,frameworks from multinuclear zinc cluster SBUs,including dinuclear (Zn 2)[4],trinu-clear (Zn 3)[5],tetranuclear (Zn 4)[6],pentanuclear (Zn 5)[7],hexanuclear (Zn 6)[8],heptanuclear (Zn 7)[9],and octanuclear (Zn 8)[10]clusters have attracted great interest and have been investigated extensively.Addi-tionally,a series of systematic studies on this subject has demonstrated that an interpenetrated array cannot prevent porosity,but enhances the porous functionalities of the supramolecular frameworks [11].More importantly,the research upsurge in interpenetration structures was pro-moted by the fact that interpenetrated nets have been considered as potential super-hard materials [12]and possess peculiar optical and electrical properties [13].Herein we present the synthesis,structure,and spectral properties of a new coordination polymer based on tetranuclear homometallic cluster,Zn 2(OH)(pheno)(p -BDC)1.5ÁH 2O (1).2Experimental2.1Materials and MeasurementsAll commercially available chemicals are reagent grade and used as received without further puriﬁcation.Sol-vents were puriﬁed by standard methods prior to use.Elemental analysis for C,H and N were carried with a Perkin-Elmer 240C Elemental Analyzer at the Analysis Center of Nanjing University.Infrared spectra were obtained with a Bruker FS66V FT IR Spectrophotometer as a KBr pellet.R.-Y.Huang ÁX.-J.Kong ÁG.-X.Liu (&)Anhui Key Laboratory of Functional Coordination Compounds,College of Chemistry and Chemical Engineering,Anqing Normal University,Anqing 246003,P.R.China e-mail:liugx@J Inorg Organomet Polym (2008)18:304–308DOI 10.1007/s10904-008-9199-72.2Preparation of Zn2(OH)(pheno)(p-BDC)1.5ÁH2O(1)A mixture containing Zn(NO3)2Á6H2O(0.20mmol), p-1,4-benzenedicarboxylic acid(H2BDC)(0.20mmol), phenanthrene-9,10-dione(pheno)(0.10mmol)and NaOH (0.20mmol)in water(10mL)was sealed in a18mL Teﬂon lined stainless steel container and heated at150°C for72h.The reaction product was dark yellow block crystals of1,which were washed by deionized water sev-eral times and collected byﬁltration;Yield,78%. Elemental Analysis:Calcd.for C24H15N2O10Zn2:C,46.33; H,2.43;N,4.50%.Found:C,46.38;H,2.47;N,4.48%.IR (KBr pellet),cm-1(intensity):3437(br),3062(m),1587 (s),1523(m),1491(w),1424(m),1391(s),1226(w),1147 (w),1103(w),1051(w),875(w),843(m),740(w),728 (m),657(w).2.3X-ray Structure DeterminationThe crystallographic data collections for complex1were carried out on a Bruker Smart Apex II CCD with graphite-monochromated Mo-K a radiation(k=0.71073A˚)at 293(2)K using the x-scan technique.The data were inte-grated by using the SAINT program[14],which also did the intensities corrected for Lorentz and polarization effects.An empirical absorption correction was applied using the SADABS program[15].The structures were solved by direct methods using the SHELXS-97program; and,all non-hydrogen atoms were reﬁned anisotropically on F2by the full-matrix least-squares technique using the SHELXL-97crystallographic software package[16,17]. The hydrogen atoms were generated geometrically.All calculations were performed on a personal computer with the SHELXL-97crystallographic software package[17].The details of the crystal parameters,data collection and reﬁnement for four compounds are summarized in Table1. Selected bond lengths and bong angles for complex1are listed in Table2.3Results and DiscussionThe X-ray diffraction study for1reveals that the material crystallizes in the orthorhombic space group Pbca and features a2-fold parallel interpenetrated3D?3D net-work motif.The asymmetric unit contains two Zn(II) atoms,one hydroxyl,one pheno ligand,one and half of p-BDC molecules and one solvent water molecule.Selected bond lengths for1are listed in Table2.As shown in Fig.1, the Zn1ion,which is in the center of a tetrahedral geom-etry,is surrounded by three carboxylic oxygen atoms (Zn–O=1.918(5)–1.964(5)A˚)from three p-BDC ligands and one l3-OH oxygen atom(O9).The Zn–O distance is 1.965(5)A˚.Two nitrogen atoms(N1and N2)that belong to pheno,one p-BDC oxygen atom(O3A)and one hydroxyl oxygen atom(O9A)are ligated to the Zn2center in the equatorial plane with another oxygen atom(O9)that arises from the second hydroxyl group and one oxygen atom(O5)that arises from the second p-BDC molecule situated in the axial position.Each Zn2lies approximately in the equatorial position with a maximum deviation (0.048A˚)from the basal plane.In the structure,Zn–O and Zn–N bond distances are in the range of 2.0530(5)–2.112(5)and2.157(5)–2.184(2)A˚,respectively.There exist two types of p-BDC found in1(Scheme1); namely,monobidentate bridging(l3)and bi-bidentate bridging(l4)coordination modes.The bidentate bridging p-BDC connects mixed metals,where the smallest ZnÁÁÁZn distance is3.163A˚,to complete a homodinuclear cluster, which is further linked by l3-OH into a six-connected Table1Crystal data and summary of X-ray data collection for1Zn2(pheno)(OH)(BDC)1.5ÁH2O Empirical formula C24H15N2O10Zn2Molecular mass/g mol-1622.12Color of crystal Dark yellowCrystal fdimensions/mm0.1890.1690.12 Temperature/K293Lattice dimensionsa/A˚18.777(9)b/A˚13.657(6)c/A˚19.983(9)a/°90b/°90c/°90Unit cell volume(A˚3)5125(4)Crystal system OrthorhombicSpace group PbcaZ8l(Mo-K a)/mm-1 1.931D(cacl.)/g cm-3 1.613Radiation type Mo-K aF(000)2504Limits of data collection/° 2.04B h B25.05Total reﬂections24155Unique reﬂections,parameters4545,347No.with I[2r(I)2821R1indices[I[2r(I)]0.0657w R2indices0.1858Goodness ofﬁt 1.060Min/max peak(Final diff.map)/e A˚-3-0.658/2.322tetranuclear cluster that is jointly coordinated by six p-BDC molecules(Fig.2).The clusters are further extended by p-BDC into a single3D framework(Fig.3).For clarity, we used the topological method to analyze this3D framework.Thus,the six-connected SBU is viewed to be a six-connected node.Furthermore,based on consideration of the geometry of this node,the3D frame is classiﬁed as an a-Po net with41263topology(Fig.4).Of particular interest,the most intriguing feature of complex1is that a pair of identical3D single nets is interlocked with each other,thus directly leading to the formation of a2-fold interpenetrated3D?3D architecture(Fig.4)and the two pcu(a-Po)frameworks are related by a screw axis21[18]. Recently,a complete analysis of3D coordination networks shows that more than50interpenetrated pcu(a-Po)frames have been documented in the CSD database[18],including 2-fold,3-fold[19],and4-fold[20]interpenetration.In addition,several non-interpenetration motifs with a-Po topology have been reported to date[21].ZnZnO ZnZnZnZnO Znbidentate bidentate bidentate monodentateI IIScheme1Coordination modesof the bdc ligands in the structure of1;I is bis(bidentate),II is bi/monodentateFig.1ORTEP representation of complex1(the H atoms have beenomitted for the sake of clarity).The thermal ellipsoids are drawn at30%probabilityTable2Selected bond lengths(A˚)and angles(°)for1Symmetry transformations usedto generate equivalent atoms:#1x-1/2,y,-z+1/2;#2-x,-y+1,-z;#3-x+1/2,-y+1,z-1/2Zn(1)–O(1) 1.918(5)Zn(2)–O(9)#2 2.091(4)Zn(1)–O(4)#1 1.953(5)Zn(2)–O(9) 2.103(5)Zn(1)–O(6) 1.964(5)Zn(2)–O(3)#3 2.112(5)Zn(1)–O(9) 1.965(5)Zn(2)–N(1) 2.157(6)Zn(2)–O(5)#2 2.053(5)Zn(2)–N(2) 2.184(6)O(1)–Zn(1)–O(4)#197.9(2)O(9)–Zn(2)–O(3)#388.81(18)O(1)–Zn(1)–O(6)112.9(2)O(5)#2–Zn(2)–N(1)94.7(2)O(4)#1–Zn(1)–O(6)104.7(2)O(9)#2–Zn(2)–N(1)170.7(2)O(1)–Zn(1)–O(9)122.9(2)O(9)–Zn(2)–N(1)91.6(2)O(4)#1–Zn(1)–O(9)109.7(2)O(3)#3–Zn(2)–N(1)88.9(2)O(6)–Zn(1)–O(9)107.0(2)O(5)#2–Zn(2)–N(2)87.1(2)O(5)#2–Zn(2)–O(9)#291.9(2)O(9)#2–Zn(2)–N(2)98.3(2)O(5)#2–Zn(2)–O(9)173.72(19)O(9)–Zn(2)–N(2)94.5(2)O(9)#2–Zn(2)–O(9)81.82(19)O(3)#3–Zn(2)–N(2)164.3(2)O(5)#2–Zn(2)–O(3)#391.3(2)N(1)–Zn(2)–N(2)75.7(2)O(9)#2–Zn(2)–O(3)#397.42(19)Fig.2Polyhedral representation of the homotetranuclear unit as asix-connected node linked by p-BDC ligandsMoreover,rich inter and intra hydrogen-bonds between the water molecules and the carboxylate groups (Table 3)further strengthen the stacking of the supra-architecture (Fig.5).4Supplementary MaterialsCrystallographic data (excluding structure factors)for thestructures reported in this paper have been deposited with the Cambridge Crystallographic Data Center as supple-mentary publication DC-666555.Copies of the data can be obtained free of charge on application to CCDC,12Union Road,Cambridge CB21EZ,UK (Fax:+44-1223-336033;e-mail:deposit@).Acknowledgments This work was supported by the National Nat-ural Science Foundation of China (20731004)and the Natural Science Foundation of the Education Committee of Anhui Province,China(KJ2008B004).Fig.3Polyhedral presentation of one set of the 3D network along a -axis (a )and b -axis (b )Table 3Distance (A ˚)and angles (°)of hydrogen bonding for com-plex 1D–H ÁÁÁADistance of D ÁÁÁA (A ˚)Angle of D–H–A (°)O1W–H1WB ÁÁÁO2#1 2.677(9)164O9–H19ÁÁÁO1W#2 2.841(9)151C13–H13ÁÁÁO3#3 3.045(10)121C22–H22ÁÁÁO1W#43.353(10)167Symmetry transformations used to generate equivalent atoms:#1x,y,1+z;#2-x,1-y,-1+z;#3-x+1/2,-y+1,z -1/2;#4-x,1-y,1-zFig.4Simpliﬁed schematic representation of the 3D ?3D two-fold interpenetrated a -Po network in1Fig.5Projection of the structure of 1along b -axis (dotted lines represent 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The chemistry and applications of metal organic framworks

DOI: 10.1126/science.1230444, (2013);341 Science et al.Hiroyasu Furukawa The Chemistry and Applications of Metal-Organic FrameworksThis copy is for your personal, non-commercial use only.clicking here.colleagues, clients, or customers by , you can order high-quality copies for your If you wish to distribute this article to othershere.following the guidelines can be obtained by Permission to republish or repurpose articles or portions of articles): May 10, 2014 (this information is current as of The following resources related to this article are available online at/content/341/6149/1230444.full.html version of this article at:including high-resolution figures, can be found in the online Updated information and services, /content/suppl/2013/08/29/341.6149.1230444.DC1.html can be found at:Supporting Online Material /content/341/6149/1230444.full.html#ref-list-1, 13 of which can be accessed free:cites 358 articles This article /content/341/6149/1230444.full.html#related-urls 2 articles hosted by HighWire Press; see:cited by This article has been/cgi/collection/chemistry Chemistrysubject collections:This article appears in the following registered trademark of AAAS.is a Science 2013 by the American Association for the Advancement of Science; all rights reserved. The title Copyright American Association for the Advancement of Science, 1200 New York Avenue NW, Washington, DC 20005. (print ISSN 0036-8075; online ISSN 1095-9203) is published weekly, except the last week in December, by the Science o n M a y 10, 2014w w w .s c i e n c e m a g .o r g D o w n l o a d e d f r o m/10.1126/science.1230444Cite this article as H. FurukawaScienceDOI: 10.1126/science.1230444 liations is available in the full article online.*Corresponding author. E-mail: yaghi@30 AUGUST 2013 VOL 341 SCIENCE Published by AAASThe Chemistry and Applications of Metal-Organic FrameworksHiroyasu Furukawa,1,2Kyle E.Cordova,1,2Michael O’Keeffe,3,4Omar M.Yaghi1,2,4* Crystalline metal-organic frameworks(MOFs)are formed by reticular synthesis,which creates strong bonds between inorganic and organic units.Careful selection of MOF constituents can yield crystals of ultrahigh porosity and high thermal and chemical stability.These characteristics allow the interior of MOFs to be chemically altered for use in gas separation,gas storage,and catalysis,among other applications.The precision commonly exercised in their chemical modification and the ability to expand their metrics without changing the underlying topology have not been achieved with other solids.MOFs whose chemical composition and shape of building units can be multiply varied within a particular structure already exist and may lead to materials that offer a synergistic combination of properties.T he past decade has seen explosive growth in the preparation,characterization,andstudy of materials known as metal-organic frameworks(MOFs).These materials are con-structed by joining metal-containing units[sec-ondary building units(SBUs)]with organic linkers, using strong bonds(reticular synthesis)to create open crystalline frameworks with permanent po-rosity(1).The flexibility with which the metal SBUs and organic linkers can be varied has led to thousands of compounds being prepared and studied each year(Figs.1and2).MOFs have ex-ceptional porosity and a wide range of potential uses including gas storage,separations,and ca-talysis(2).In particular,applications in energy technologies such as fuel cells,supercapacitors, and catalytic conversions have made them ob-jects of extensive study,industrial-scale produc-tion,and application(2–4).Among the many developments made in this field,four were particularly important in advanc-ing the chemistry of MOFs:(i)The geometric principle of construction was realized by the link-ing of SBUs with rigid shapes such as squares and octahedra,rather than the simpler node-and-spacer construction of earlier coordination net-works in which single atoms were linked by ditopic coordinating linkers(1).The SBU approach not only led to the identification of a small number of preferred(“default”)topologies that could be targeted in designed syntheses,but also was cen-tral to the achievement of permanent porosity in MOFs(1).(ii)As a natural outcome of the use of SBUs,a large body of work was subsequently reported on the use of the isoreticular principle (varying the size and nature of a structure without changing its underlying topology)in the design of MOFs with ultrahigh porosity and unusuallylarge pore openings(5).(iii)Postsynthetic mod-ification(PSM)of MOFs—incorporating organicunits and metal-organic complexes through re-actions with linkers—has emerged as a powerfultool for changing the reactivity of the pores(e.g.,creating catalytic sites)(6).(iv)Multivariate MOFs(MTV-MOFs),in which multiple organic function-alities are incorporated within a single framework,have provided many opportunities for designingcomplexity within the pores of MOFs in a con-trolled manner(7).Below,we focus on these aspects of MOFchemistry because they are rarely achieved in oth-er materials and because they lead to the previous-ly elusive synthesis of solids by design.Unlikeother extended solids,MOFs maintain their under-lying structure and crystalline order upon expan-sion of organic linkers and inorganic SBUs,aswell as after chemical functionalization,whichgreatly widens the scope of this chemistry.Wereview key developments in these areas and dis-cuss the impact of this chemistry on applicationssuch as gas adsorption and storage,catalysis,andproton conduction.We also discuss the conceptof MTV-MOFs in relation to the sequence of func-tionality arrangement that is influenced by theelectronic and/or steric interactions among thefunctionalities.Highly functional synthetic crys-talline materials can result from the use of suchtechniques to create heterogeneity within MOFstructures.Design of Ultrahigh PorosityDuring the past century,extensive work was doneon crystalline extended structures in which metalions are joined by organic linkers containing Lewisbase–binding atoms such as nitriles and bipyridines(8,9).Although these are extended crystal struc-tures and not large discrete molecules such as poly-mers,they were dubbed coordination“polymers”—a term that is still in use today,although we preferthe more descriptive term MOFs,introduced in1995(10)and now widely accepted.Becausethese structures were constructed from long or-ganic linkers,they encompassed void space andtherefore were viewed to have the potential to be1Department of Chemistry,University of California,Berkeley,CA94720,USA.2Materials Sciences Division,Lawrence Berkeley National Laboratory,Berkeley,CA94720,USA.3Department of Chemistry,Arizona State University,Tempe,AZ87240,USA. 4NanoCentury KAIST Institute and Graduate School of Energy,Environment,Water,and Sustainability(World Class Univer-sity),Daejeon305-701,Republic of Korea.*Corresponding author.E-mail:yaghi@ln(No.ofstructures)YearDoubling time9.3 years5.7 years3.9 years2010200520001995199019851980197512108642No.ofMOFstructures7000600050004000300020001000Year2122222199199199199199198198198198198197197197197Total (CSD)Extended (1D, 2D, 3D)MOFs (3D)Fig.1.Metal-organic framework structures(1D,2D,and3D)reported in the Cambridge Struc-tural Database(CSD)from1971to2011.The trend shows a striking increase during this period for all structure types.In particular,the doubling time for the number of3D MOFs(inset)is the highest among all reported metal-organic structures. SCIENCE VOL34130AUGUST20131230444-1BAZn 4O(CO 2)6M 3O 3(CO 2)3 (M = Zn, Mg, Co, Ni, Mn, Fe, and Cu)Ni 4(C 3H 3N 2)8In(C 5HO 4N 2)4Zr 6O 4(OH)4-(CO 2)12Zr 6O 8(CO 2)8M 3O(CO 2)6 (M = Zn, Cr, In, and Ga)M 2(CO 2)4(M = Cu, Zn, Fe, Mo, Cr, Co, and Ru)Zn(C 3H 3N 2)4Na(OH)2(SO 3)3Cu 2(CNS)4H 2BDCH 4DOTH 2BDC-X (X = Br, OH, NO 2, and NH 2)H 2BDC-(X)2(X = Me, Cl, COOH, OC 3H 5, and OC 7H 7)H 4ADBFumaric acidOxalic acidH 4ATC H 3THBTSH 3ImDCDTOAADPH 3BTPTIPA Gly-AlaH 4DH9PhDC H 4DH11PhDCH 3BTCIr(H 2DPBPyDC)(PPy)2+H 6BTETCADCDPBN BPP34C10DAH 3BTB (X = CH)H 3TATB (X = N)H 3BTE (X = C ≡C)H 3BBC (X = C 6H 4)H 6TPBTM (X = CONH)H 6BTEI (X = C ≡C)H 6BTPI (X = C 6H 4)H 6BHEI (X = C ≡C−C ≡C)H 6BTTI (X = (C 6H 4)2)H 6PTEI (X = C 6H 4−C ≡C)H 6TTEI (X = C ≡C-C 6H 4-C ≡C)H 6BNETPI (X = C ≡C−C 6H 4−C ≡C−C ≡C)H 6BHEHPI (X = (C 6H 4−C ≡C)2)COOHCOOHCOOHCOOH COOHCOOHOH HOCOOHCOOHXCOOHCOOHX XCOOHHOOCCOOHHOOC OHOO OHNCOOHHOOCNHOOCCOOHN NH HOOCCOOHNNH N HNNHN SO 3H SO 3HHO 3SOHHOOH NH 2H 2NSSN NNN NNNCOOHHOOCCOOHH N H 2NOCOOHOHCOOHHOCOOHOHHOCOOHCOOHHOOCCOOHX XXCOOHHOOCCOOHNN OH OHClClCOOHHOOCCOOHCOOHCOOHHOOCOOOOOCOOHCOOH OOOOONNCOOHCOOHIr NN+COOHHOOCCOOHXXXCOOHCOOHHOOCCOOHHOOCCOOHXXX Al(OH)(CO 2)2 VO(CO 2)2Fig.2.Inorganic secondary building units (A)and organic linkers (B)referred to in the text.Color code:black,C;red,O;green,N;yellow,S;purple,P;light green,Cl;blue polyhedra,metal ions.Hydrogen atoms are omitted for clarity.AIPA,tris(4-(1H -imidazol-1-yl)phenyl)amine;ADP,adipic acid;TTFTB4–,4,4′,4′′,4′′′-([2,2′-bis(1,3-dithiolylidene)]-4,4′,5,5′-tetrayl)tetrabenzoate.30AUGUST 2013VOL 341SCIENCE 1230444-2REVIEWpermanently porous,as is the case for zeolites.The porosity of these compounds was investigated in the1990s by forcing gas molecules into the crev-ices at high pressure(11).However,proof of per-manent porosity requires measurement of reversible gas sorption isotherms at low pressures and tem-peratures.Nonetheless,as we remarked at that time(12),it was then commonplace to refer to materials as“porous”and“open framework”even though such proof was lacking.The first proof of permanent porosity of MOFs was obtained by mea-surement of nitrogen and carbon dioxide isotherms on layered zinc terephthalate MOF(12).A major advance in the chemistry of MOFs came in1999when the synthesis,x-ray single-crystal structure determination,and low-temperature, low-pressure gas sorption properties were reported for the first robust and highly porous MOF,MOF-5 (13).This archetype solid comprises Zn4O(CO2)6 octahedral SBUs each linked by six chelating 1,4-benzenedicarboxylate(BDC2–)units to give a cubic framework(Fig.2,figs.S2and S3,and tables S1and S2).The architectural robustness of MOF-5allowed for gas sorption measurements, which revealed61%porosity and a Brunauer-Emmett-Teller(BET)surface area of2320m2/g (2900m2/g Langmuir).These values are substan-tially higher than those commonly found for zeo-lites and activated carbon(14).To prepare MOFs with even higher surface area(ultrahigh porosity)requires an increase in storage space per weight of the material.Longer organic linkers provide larger storage space and a greater number of adsorption sites within a given material.However,the large space within the crys-tal framework makes it prone to form interpen-etrating structures(two or more frameworks grow and mutually intertwine together).The most effec-tive way to prevent interpenetration is by making MOFs whose topology inhibits interpenetration because it would require the second framework to have a different topology(15).Additionally, it is important to keep the pore diameter in the micropore range(below2nm)by judicious se-lection of organic linkers in order to maximize the BETsurface area of the framework,because it is known that BET surface areas obtained from isotherms are similar to the geometric surface areas derived from the crystal structure(16).In2004, MOF-177[Zn4O(BTB)2;BTB=4,4′,4′′-benzene-1,3,5-triyl-tribenzoate]was reported with the high-est surface area at that time(BET surface area= 3780m2/g,porosity=83%;Figs.3A and4)(15), which satisfies the above requirements.In2010, the surface area was doubled by MOF-200and MOF-210[Zn4O(BBC)2and(Zn4O)3(BTE)4(BPDC)3, respectively;BBC3–=4,4′,4′′-(benzene-1,3,5-triyl-tris(benzene-4,1-diyl))tribenzoate;BTE= 4,4′,4′′-(benzene-1,3,5-triyl-tris(ethyne-2,1-diyl)) tribenzoate;BPDC=biphenyl-4,4′-dicarboxylate] to produce ultrahigh surface areas(4530m2/g and6240m2/g,respectively)and porosities(90% and89%)(17).An x-ray diffraction study performed on a sin-gle crystal of MOF-5dosed with nitrogen or argon gas identified the adsorption sites within the pores(18).The zinc oxide SBU,the faces,and,sur-prisingly,the edges of the BDC2–linker serve asadsorption sites.This study uncovered the originof the high porosity and has enabled the design ofMOFs with even higher porosities(Fig.4and ta-ble S3).Moreover,it has been reported that ex-panded tritopic linkers based on alkyne rather thanphenylene units should increase the number ofadsorption sites and increase the surface area(19).NU-110[Cu3(BHEHPI);BHEHPI6–=5,5′,5′′-((((benzene-1,3,5-triyltris(benzene-4,1-diyl))tris(ethyne-2,1-diyl))-tris(benzene-4,1-diyl))tris(ethyne-2,1-diyl))triisophthalate],whose organiclinker is replete with such edges,displayed a sur-face area of7140m2/g(Table1)(7,17,20–32).For many practical purposes,such as storinggases,calculating the surface area per volumeis more relevant.By this standard,the value forMOF-5,2200m2/cm3,is among the very bestreported for MOFs(for comparison,the value forNU-110is1600m2/cm3).Note that the externalsurface area of a nanocube with edges measuring3nm would be2000m2/cm3.However,nano-crystallites on this scale with“clean”surfaceswould immediately aggregate,ultimately leavingtheir potential high surface area inaccessible.Expansion of Structures by a Factor of2to17A family of16cubic MOFs—IRMOF-1[alsoknown as MOF-5,which is the parent MOF ofthe isoreticular(IR)series]to IRMOF-16—withthe same underlying topology(isoreticular)wasmade with expanded and variously functionalizedorganic linkers(figs.S2and S3)(1,5).This de-velopment heralded the potential for expandingand functionalizing MOFs for applications in gasstorage and separations.The same work demon-strated that a large number of topologically iden-tical but functionally distinctive structures can bemade.Note that the topology of these isoreticularMOFs is typically represented with a three-lettercode,pcu,which refers to its primitive cubic net(33).One of the smallest isoreticular structuresof MOF-5is Zn4O(fumarate)3(34);one of thelargest is IRMOF-16[Zn4O(TPDC)3;TPDC2–=terphenyl-4,4′′-dicarboxylate](5)(fig.S2).In thisexpansion,the unit cell edge is doubled and itsvolume is increased by a factor of8.The degreeof interpenetration,and thus the porosity and den-sity of these materials,can be controlled by chang-ing the concentration of reactants,temperature,orother experimental conditions(5).The concept of the isoreticular expansion isnot simply limited to cubic(pcu)structures,asillustrated by the expansion of MOF-177to giveMOF-180[Zn4O(BTE)2]and MOF-200,whichuse larger triangular organic linkers(qom net;Fig.3A and fig.S4)(15,17).Contrary to the MOF-5type of expanded framework,expanded structuresof MOF-177are noninterpenetrating despite thehigh porosity of these MOFs(89%and90%forMOF-180and MOF-200,respectively).Theseresults highlight the critical role of selectingtopology.Another MOF of interest is known as HKUST-1[Cu3(BTC)2;BTC3–=benzene-1,3,5-tricarboxylate](35);it is composed of Cu paddlewheel[Cu2(CO2)4]SBUs(Fig.2A)and a tritopic organic linker,BTC3–.Several isoreticular structures have been madeby expansion with TA TB3–[4,4′,4′′-(1,3,5-triazine-2,4,6-triyl)tribenzoate],TA TAB3–[4,4′,4′′-((1,3,5-triazine-2,4,6-triyl)tris(azanediyl))tribenzoate],TTCA3–[triphenylene-2,6,10-tricarboxylate],HTB3–[4,4′,4′′-(1,3,3a1,4,6,7,9-heptaazaphenalene-2,5,8-triyl)tribenzoate],and BBC3–linkers(tbonet;Fig.3B,fig.S1and S5,and tables S1andS2)(21,36–39).The cell volume for the largestreported member[MOF-399,Cu3(BBC)2]is17.4times that of HKUST-1.MOF-399has thehighest void fraction(94%)and lowest density(0.126g/cm3)of any MOF reported to date(21).Cu paddlewheel units are also combined withvarious lengths of hexatopic linkers to form an-other isoreticular series.The first example of oneof these MOFs is Zn3(TPBTM)[TPBTM6–=5,5′,5′′-((benzene-1,3,5-tricarbonyl)tris(azanediyl))triisophthalate],which has a ntt net(40).Shortlyafter this report,several isoreticular MOF struc-tures were synthesized(Fig.3C and fig.S6)(19,20,24,41–48):Cu3(TPBTM),Cu3(TDPA T),NOTT-112[Cu3(BTPI)],NOTT-116[also knownas PCN-68;Cu3(PTEI)],PCN-61[Cu3(BTEI)],PCN-66[Cu3(NTEI)],PCN-69[also known asNOTT-119;Cu3(BTTI)],PCN-610[also knownas NU-100;Cu3(TTEI)],NU-108[Cu3(BTETCA)],NU-109[Cu3(BNETPI)],NU-110,and NU-111[Cu3(BHEI)]TDPA T6–=5,5′,5′′-((1,3,5-triazine-2,4,6-triyl)tris(azanediyl))triisophthalate;BTPI6–=5,5′,5′′-(benzene-1,3,5-triyl-tris(benzene-4,1-diyl))triisophthalate;PTEI6–=5,5′,5′′-((benzene-1,3,5-triyl-tris(benzene-4,1-diyl))tris(ethyne-2,1-diyl))triisophthalate;BTEI6–=5,5′,5′′-(benzene-1,3,5-triyl-tris(ethyne-2,1-diyl))triisophthalate;NTEI6–=5,5′,5′′-((nitrilotris(benzene-4,1-diyl))tris(ethyne-2,1-diyl))triisophthalate;BTTI6–=5,5′,5′′-(benzene-1,3,5-triyl-tris(biphenyl-4,4′-diyl))triisophthalate;TTEI6–=5,5′,5′′-(((benzene-1,3,5-triyl-tris(ethyne-2,1-diyl))tris(benzene-4,1-diyl))tris(ethyne-2,1-diyl))triisophthalate;BTETCA6–=5′,5′′′′,5′′′′′′′-(benzene-1,3,5-triyl-tris(ethyne-2,1-diyl))tris(([1,1′:3′,1′′-terphenyl]-4,4′′-dicarboxylate));BNETPI6–=5,5′,5″-(((benzene-1,3,5-triyl-tris(ethyne-2,1-diyl))tris(benzene-4,1-diyl))tris(buta-1,3-diyne-4,1-diyl))triisophthalate;BHEI6–=5,5′,5″-(benzene-1,3,5-triyl-tris(buta-1,3-diyne-4,1-diyl))triisophthalate].Isoreticularmaterials are not necessarily expansions of theoriginal parent MOF,as exemplified by NU-108,because the ntt family has a linker(BTETCA6–)with two branching points and two kinds of links(figs.S1B and S7).A wide variety of metal ions form metal-carboxylate units,and isostructural MOFs can besynthesized by replacing the metal ions in theinorganic SBUs.Indeed,after the appearance ofHKUST-1[Cu3(BTC)2],an isostructural series ofHKUST-1[M3(BTC)2,where M=Zn(II),Fe(II),Mo(II),Cr(II),Ru(II)]was prepared by sever-al groups(fig.S5)(49–53).In the same way as SCIENCE VOL34130AUGUST20131230444-3REVIEWABDCZn 4O(CO 2)6Cu 2(CO 2)4Cu 2(CO 2)4Zn 4O(BTB)2MOF-177 (qom )Cu 3(BTC)2, HKUST -1MOF-199 (tbo )Cu 3(BBC)2,MOF-399 (tbo )Cu 3(TATB)2, PCN-6’ (tbo )Zn 4O(BTE)2MOF-180 (qom )Zn 4O(BBC)2MOF-200 (qom )× 1.820 Å× 2.7Tritopic linker20 Å× 5.5× 17.4Hexatopic linker30 Å× 2.2× 6.0× 6.5× 16.130 ÅTetratopic linkerCu 3(TDPAT) (ntt )Cu 3(NTEI),PCN-66 (ntt )Cu 3(BHEHPI),NU-110 (ntt )Mg 3O 3(CO 2)3Mg 2(DOT), Mg-MOF-74(IRMOF-74-I) (etb )Mg 2(DH11PhDC),IRMOF-74-XI (etb )Mg 2(DH5PhDC),IRMOF-74-V (etb )Tritopic linkerFig. 3.Isoreticular expansion of metal-organic frameworks with qom,tbo,ntt,and etb nets.(A to D )The isoreticular (maintaining same topology)expansion of archetypical metal-organic frameworks resulting from discrete [(A),(B),and (C)]and rod inorganic SBUs (D)combined with tri-,hexa-,and tetratopic organic linkers to obtain MOFs in qom (A),tbo (B),ntt (C),and etb (D)nets,respectively.Each panel shows a scaled comparison of the smallest,medium,and largest crystalline structures of MOFs representative of these nets.The large yellow and green spheres represent the largest sphere that would occupy the cavity.Numbers above each arrow represent the degree of volume expansion from the smallest framework.Color code is same as in Fig.2;hydrogen atoms are omitted for clarity.30AUGUST 2013VOL 341SCIENCE1230444-4REVIEWdiscrete inorganic SBUs,the infinite inorganic rod-type SBUs were also used to synthesize isostructural MOF-74[Zn 2(DOT);DOT =dioxidoterephthalate](54)using divalent metal ions such as Mg,Co,Ni,and Mn (fig.S8)(55).Exceptionally Large Pore AperturesPore openings of MOFs are typically large enough (up to 2nm)to accommodate small molecules,but rarely are they of appropriate size to permit inclusion of large molecules such as proteins.The best way to increase pore apertures is to use infinite rod-shaped SBUs with linkers of arbitrary length providing periodicity in the other two di-mensions,which does not allow for interpene-trating structures.This strategy was implemented by expanding the original phenylene unit of MOF-74[M 2(DOT);M 2+=Zn,Mg]structure (54)to 2,3,4,5,6,7,9,and 11phenylene units [DH2PhDC 4–to DH11PhDC 4–,respectively;Fig.2B,Fig.3D,and figs.S1B and S8](22).Crystal structures revealed that pore apertures for this series of MOF-74struc-tures (termed IRMOF-74-I to IRMOF-74-XI)ranged from 14to 98Å.The presence of the large pore apertures was also confirmed by transmission elec-tron microscopy (TEM)and scanning electron microscopy (SEM)observation as well as argon adsorption measurements of the guest-free mate-rials.As expected,the pore aperture of IRMOF-74-IX is of sufficient size to allow for green fluorescent protein (barrel structure with diameter of 34Åand length of 45Å)to pass into the pores without unfolding.More important,the large pore aperture is of benefit to the surface modification of the pores with various functionalities without sacrificing the porosity (22).An oligoethylene glycol –functionalized IRMOF-74-VII [Mg 2(DH7PhDC-oeg)]allows in-clusion of myoglobin,whereas IRMOF-74-VII with hydrophobic hexyl chains showed a negli-gible amount of inclusion.High Thermal and Chemical StabilityBecause MOFs are composed entirely of strong bonds (e.g.,C-C,C-H,C-O,and M-O),they show high thermal stability ranging from 250°to 500°C (5,56–58).It has been a challenge to make chem-ically stable MOFs because of their susceptibility to link-displacement reactions when treated with solvents over extended periods of time (days).The first example of a MOF with exceptional chemical stability is zeolitic imidazolate framework –8[ZIF-8,Zn(MIm)2;MIm –=2-methylimidazolate],which was reported in 2006(56).ZIF-8is unaltered after immersion in boiling methanol,benzene,and water for up to 7days,and in concentrated sodium hydroxide at 100°C for 24hours.201220102008200620041999010002000300040005000600070008000Typical conventionalporous materialsMOFsZ e o l i t e s (0.30)S i l i c a s (1.15)C a r b o n s (0.60)MIL-101(2.15)MIL-101 (2.00)MOF-177 (1.59)NOTT-119 (2.35)MOF-210 (3.60)NU-100 (2.82)NU-110(4.40)UMCM-2(2.32)DUT-49(2.91)MOF-5(1.04)MOF-5 (1.20)MOF-5(1.56)MOF-177 (2.00)IRMOF-20 (1.53)MOF-5 (1.48)U M C M -1 (2.24)P C N -6 (1.41)M I L -100 (1.10)M O F -200 (3.59)B i o -M O F -100 (4.30)N O T T -112 (1.59)D U T -23(C o ) (2.03)Fig.4.Progress in the synthesis of ultrahigh-porosity MOFs.BET surface areas of MOFs and typical conventional materials were estimated from gas adsorption measurements.The values in parentheses represent the pore volume (cm 3/g)of these materials.Table 1.Typical properties and applications of metal-organic frameworks.Metal-organic frameworks exhibiting the lowest and highest values for the indicated property,and those reported first for selected applications,are shown.Property or applicationCompound Achieved value or year of reportReference Lowest reported value DensityMOF-3990.126g/cm 3(21)Highest reported value Pore apertureIRMOF-74-XI 98Å(22)Number of organic linkers MTV-MOF-58(7)Degrees of interpenetration Ag 6(OH)2(H 2O)4(TIPA)554(23)BET surface area NU-1107140m 2/g (20)Pore volumeNU-110 4.40cm 3/g (20)Excess hydrogen uptake (77K,56bar)NU-1009.0wt%(24)Excess methane uptake (290K,35bar)PCN-14212mg/g (25)Excess carbon dioxide uptake (298K,50bar)MOF-2002347mg/g (17)Proton conductivity (98%relative humidity,25°C)(NH 4)2(ADP)[Zn 2(oxalate)3]·3H 2O8×10−3S/cm (26)Charge mobilityZn 2(TTFTB)0.2cm 2/V·s (27)Lithium storage capacity (after 60cycles)Zn 3(HCOO)6560mAh/g(28)Earliest reportCatalysis by a MOFCd(BPy)2(NO 3)21994(29)Gas adsorption isotherm and permanent porosity MOF-21998(12)Asymmetric catalysis with a homochiral MOF POST-12000(31)Production of open metal site MOF-112000(30)PSM on the organic linkerPOST-12000(31)Use of a MOF for magnetic resonance imagingMOF-732008(32) SCIENCE VOL 34130AUGUST 20131230444-5REVIEWMOFs based on the Zr(IV)cuboctahedral SBU (Fig.2A)also show high chemical stability;UiO-66[Zr 6O 4(OH)4(BDC)6]and its NO 2-and Br-functionalized derivatives demonstrated high acid (HCl,pH =1)and base resistance (NaOH,pH =14)(57,58).The stability also remains when tetratopic organic linkers are used;both MOF-525[Zr 6O 4(OH)4(TpCPP-H 2)3;TpCPP =tetra-para -carboxyphenylporphyrin]and 545[Zr 6O 8(TpCPP-H 2)2]are chemically stable in methanol,water,and acidic conditions for 12hours (59).Furthermore,a pyrazolate-bridged MOF [Ni 3(BTP)2;BTP 3–=4,4′,4″-(benzene-1,3,5-triyl)tris(pyrazol-1-ide)]is stable for 2weeks in a wide range of aqueous solutions (pH =2to 14)at 100°C (60).The high chemical stability observed in these MOFs is expected to enhance their per-formance in the capture of carbon dioxide from humid flue gas and extend MOFs ’applications to water-containing processes.Postsynthetic Modification (PSM):Crystals as MoleculesThe first very simple,but far from trivial,example of PSM was with the Cu paddlewheel carboxylate MOF-11[Cu 2(A TC);A TC 4–=adamantane-1,3,5,7-tetracarboxylate](30).As-prepared Cu atoms are bonded to four carboxylate O atoms,and the co-ordination shell is completed typically with coor-dinated water (Fig.2A).Subsequent removal of the water from the immobilized Cu atom leaves a coordinatively unsaturated site (“open metal site ”).Many other MOFs with such sites have now been generated and have proved to be exceptionally favorable for selective gas uptake and catalysis (61–63).The first demonstration of PSM on the or-ganic link of a MOF was reported in 2000for a homochiral MOF,POST-1[Zn 3(m 3-O)(D-PTT)6;D-PTT –=(4S ,5S )-2,2-dimethyl-5-(pyridin-4-ylcarbamoyl)-1,3-dioxolane-4-carboxylate](31).It involved N -alkylation of dangling pyridyl func-tionalities with iodomethane and 1-iodohexane to produce N -alkylated pyridinium ions exposed to the pore cavity.More recently,PSM was applied to the dan-gling amine group of IRMOF-3[Zn 4O(BDC-NH 2)3]crystals (6).The MOF was submerged in a dichloromethane solution containing acetic anhy-dride to give the amide derivative in >80%yield.Since then,a large library of organic reactions have been used to covalently functionalize MOF backbones (table S4)(64,65).UMCM-1-NH 2[(Zn 4O)3(BDC-NH 2)3(BTB)4]was also acylated with benzoic anhydride to produce the corresponding amide functionality within the pores (66).The structures of both IRMOF-3and UMCM-1-NH 2after modification showed increased hydrogen uptake relative to the parent MOFs,even though there was a reduction in overall surface area (66).PSM has also been used to dangle catalytically active centers within the pores.In an example reported in 2005,a Cd-based MOF built from 6,6′-dichloro-4,4′-di(pyridin-4-yl)-[1,1′-binaphthalene]-2,2′-diol (DCDPBN),[CdCl 2(DCDPBN)],used orthogonal dihydroxy functionalities to coordinate titanium isopropoxide [Ti(O i Pr)4],thus yielding a highly active,enantio-selective asymmetric Lewis acid catalyst (67).UMCM-1-NH 2was also functionalized in such a manner to incorporate salicylate chelating groups,which were subsequently metallated with Fe(III)and used as a catalyst for Mukaiyama aldol reac-tions over multiple catalytic cycles without loss of activity or crystallinity (68).Indeed,the remarkable retention of MOF crystallinity and porosity after undergoing the transformation reactions clearly dem-onstrates the use of MOF crystals as molecules (69).Catalytic Transformations Within the Pores The high surface areas,tunable pore metrics,and high density of active sites within the very open structures of MOFs offer many advantages to their use in catalysis (table S5).MOFs can be used to support homogeneous catalysts,stabi-lize short-lived catalysts,perform size selectiv-ity,and encapsulate catalysts within their pores (70).The first example of catalysis in an ex-tended framework,reported in 1994,involved the cyanosilylation of aldehydes in a Cd-based frame-work [Cd(BPy)2(NO 3)2;BPy =4,4′-bipyridine]as a result of axial ligand removal (29).This study also highlighted the benefits of MOFs as size-selective catalysts by excluding large sub-strates from the pores.In 2006,it was shown that removal of solvent from HKUST-1exposes open metal sites that may act as Lewis acid catalysts (71).MIL-101[Cr 3X(H 2O)2O(BDC)3;X =F,OH]and Mn-BTT {Mn 3[(Mn 4Cl)3(BTT)8]2;BTT 3–=5,5′,5″-(benzene-1,3,5-triyl)tris(tetrazol-2-ide)}have also been iden-tified as Lewis acid catalysts in which the metal oxide unit functions as the catalytic site upon lig-and removal (62,72).In addition,alkane oxida-tion,alkene oxidation,and oxidative coupling reactions have also been reported;they all rely on the metal sites within the SBUs for catalytic ac-tivity (73–75).The study of methane oxidation in vanadium-based MOF-48{VO[BDC-(Me)2];Me =methyl}is promising because the catalytic turnover and yield for this oxidation far exceed those of the analogous homogeneous catalysts (73).One early example of the use of a MOF as a het-erogeneous catalyst is PIZA-3[Mn 2(TpCPP)2Mn 3],which contains a metalloporphyrin as part of the framework (76).PIZA-3is capable of hydrox-ylating alkanes and catalyzes the epoxidation of olefins.Schiff-base and binaphthyl metal complexes have also been incorporated into MOFs to achieve olefin epoxidation and diethyl zinc (ZnEt 2)addi-tions to aromatic aldehydes,respectively (67,77).The incorporation of porphyrin units within the pores of MOFs can be accomplished during the synthesis (a “ship-in-a-bottle ”approach that cap-tures the units as the pores form),as illustrated for the zeolite-like MOF rho -ZMOF [In(HImDC)2·X;HImDC 2–=imidazoledicarboxylate,X –=coun-teranion](78).The pores of this framework accom-modate high porphyrin loadings,and the pore aperture is small enough to prevent porphyrin fromleaching out of the MOF.The porphyrin metal sites were subsequently metallated and used for the oxidation of cyclohexane.The same approach has been applied to several other systems in which polyoxometalates are encapsulated within MIL-101(Cr)and HKUST-1for applications in the oxidation of alkenes and the hydrolysis of esters in excess water (79,80).Integration of nanoparticles for catalysis by PSM has been carried out to enhance particle stability or to produce uniform size distributions.Palladium nanoparticles were incorporated with-in MIL-101(Cr)for cross-coupling reactions (81,82).Most recently,a bifunctional catalytic MOF {Zr 6O 4(OH)4[Ir(DPBPyDC)(PPy)2·X]6;DPBPyDC 2–=4,4′-([2,2′-bipyridine]-5,5′-diyl)dibenzoate,PPy =2-phenylpyridine}capable of water-splitting reactions was reported (83).This MOF uses the organic linker and an encapsulated nanoparticle to transfer an electron to a proton in solution,leading to hydrogen evolution.Gas Adsorption for Alternative Fuels and Separations for Clean AirMuch attention is being paid to increasing the storage of fuel gases such as hydrogen and meth-ane under practical conditions.The first study of hydrogen adsorption was reported in 2003for MOF-5(84).This study confirmed the potential of MOFs for application to hydrogen adsorption,which has led to the reporting of hydrogen ad-sorption data for hundreds of MOFs (85).In gen-eral,the functionality of organic linkers has little influence on hydrogen adsorption (86),whereas increasing the pore volume and surface area of MOFs markedly enhances the gravimetric hydro-gen uptake at 77K and high pressure,as exem-plified by the low-density materials:NU-100and MOF-210exhibit hydrogen adsorption as high as 7.9to 9.0weight percent (wt%)at 56bar for both MOFs and 15wt%at 80bar for MOF-210(17,24).However,increasing the surface area is not always an effective tool for increasing the volumetric hydrogen adsorption,which can be accomplished by increasing the adsorption enthalpy of hy-drogen (Q st )(87).In this context,open metal sites have been suggested and used to enhance the hydrogen uptake capacity and to improve Q st (61,85).Two MOFs with this characteristic,Zn 3(BDC)3[Cu(Pyen)][Pyen 2–=5,5′-((1E ,1′E )-(ethane-1,2-diyl-bis(azanylylidene))bis(methanylylidene))bis(3-methylpyridin-4-ol)]and Ni-MOF-74,have the highest reported initial Q st values:15.1kJ/mol and 12.9kJ/mol,respectively (58,88).Metal impreg-nation has also been suggested by computation as a method for increasing the Q st values (89).Experiments along these lines show that dop-ing MOFs with alkali metal cations yields only modest enhancements in the total hydrogen up-take and Q st values (90,91).Although some chal-lenges remain in meeting the U.S.Department of Energy (DOE)system targets (5.5wt%and 40g/liter at –40°to 60°C below 100bar)for hy-drogen adsorption (85),Mercedes-Benz has al-ready deployed MOF hydrogen fuel tanks in a30AUGUST 2013VOL 341SCIENCE1230444-6REVIEW。

Highly reactive {001} facets of TiO2-based composites synthesis

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Cite this: Nanoscale, 2014, 6, 1946
Highly reactive {001} facets of TiO2-based composites: synthesis, formation mechanism and characterization
1. Introduction
Dr Chai Siang Piao received his Bachelor of Engineering degree in Chemical Engineering (First Class Honours) from Universiti Sains Malaysia in 2004. He obtained his Ph.D. degree in Chemical Engineering from the School of Chemical Engineering, Universiti Sains Malaysia in 2008. Currently, he is a Senior Lecturer in Monash University Sunway Campus, Malaysia. He is an active researcher in the areas of catalysis, reaction engineering, membrane technology, carbon dioxide adsorption and utilization, natural gas processing technology, surface engineering and nanotechnology. His current research interests primarily focus on carbon nanomaterials (carbon nanotubes, graphene and nanoporous carbon) and advanced hybrid nanocomposites for environmental remediation and renewable fuels in photocatalysis. To date, he has published more than 50 research papers in peer-reviewed international journals with an hindex of 11 and over 400 total citations. With industrialization and rapid population growth, the environmental pollution and energy shortages have steadily raised awareness of a potential global crisis and are becoming overwhelming concerns all over the world. For the sustainable development of human society, the advancement of both pollution-free technologies for environmental decontamination and alternative clean energy supplies is an urgent task. Among various green earth and renewable energy projects underway, semiconductor photocatalysis has gained considerable interdisciplinary attention and much research fascination due to its diverse potential in energy and environmental applications. Generally, photocatalytic application of wide reaching importance mainly involves the degradation of pollutants,1 water splitting for hydrogen production2 and photocatalytic conversion of CO2 to energy-rich hydrocarbon fuels3,4 and presents itself as a green chemistry technology.5 Since the rst demonstration of photocatalytic water splitting using TiO2 electrodes by Fujishima and Honda under ultraviolet (UV) light in 1972,2 there has been signicant progress in the design of eﬃcient semiconductor photocatalysts. Thus, to date, developing high-quality, eﬀective and stable