石墨烯外国文献翻译
石墨烯英文介绍
Composite Material
The main field contained such as Polymer and Inorganic Nano-materials.
Thank you for listening
Guilin University of Technology
张耕
Optical Properties
Voltage applied to the bigrid double-deck graphene field effect transistor, bandgap is around 0~0.25eV.
Magnetic Field applied to the nanobelt, responsiveness could up to the large range of terahertz.
Photosensitive Element
Penetrate specific construction, low energy standard, used in satellite imagery.
New Energy Battery
Nomo GP attached on the surface, lowering the transparent and transformable solar cell.
Redox Reaction Use vitriol and nitric acid, hydrogen peroxide and so forth.
Epitaxial Growth of SiC Absolute vacuum with high temperature, silicon atoms get rid of the materials.
双层石墨烯屏蔽,Kohn异常,Friedel振荡和RKKY相互作用研究(外文翻译完整版)
双层石墨烯屏蔽，Kohn 异常，Friedel 振荡和RKKY 相互作用研究E. H. Hwang and S. Das SarmaCondensed Matter Theory Center, Department of Physics,University of Maryland, College Park, Maryland 20742-4111(Dated: April 14, 2008)我们用无规则近似计算了双层石墨烯內稟（非掺杂）和外禀（掺杂）时的屏蔽效应，并与相应的单层石墨烯和传统二维电子气结果作比较。
我们发现双层石墨烯中Kohn 异常明显增强。
我们还讨论了Friedel 振荡和RKKY 相互作用，这与F k q 2 时，屏蔽的非解析行为相关。
我们发现，双层石墨烯与单层石墨烯和二维电子气相比，屏蔽，Kohn 异常，Friedel 振荡和RKKY 相互作用具有本质的不同。
单层石墨烯是由单层碳原子排列在蜂窝状晶格中构成，理论上和实验上都受到了极大地关注，例如其独特的电子传输和相对载流子特性表现与无质量的手性狄拉克费米子类似。
双层石墨烯由两层单层石墨烯组成，目前在技术应用和基础领域方面受到各方关注。
单层石墨烯的能带结构具有线性色散关系，双层石墨烯在低能量范围具有二阶色散关系，除了没能隙外，这使它与二维半导体系统类似。
这项工作的目的是利用无规则近似计算双层石墨烯的极化率（或屏蔽）函数。
尽管许多有关单层石墨烯库仑屏蔽的理论工作已被报道，但是，关于双层石墨烯库仑屏蔽的研究尚未开展。
了解双层石墨烯的屏蔽效应是至关重要的，因为它决定了许多基本特性，例如：电荷杂质通过屏蔽的库仑散射进行运输，声子色散中的Kohn 异常，RKKY 相互作用。
为了了解双层石墨烯的电子特性，有必要研究其屏蔽效应。
双层石墨烯在某种意义上介于单层石墨烯和基于半导体的传统二维电子气之间，因为在狄拉克点（价带和导带相交）它具有手性零带隙，这与单层石墨烯类似，但是二阶能量色散关系与二维电子气类似。
“Graphene”研究及翻译
“Graphene”研究及翻译摘要：查阅近5年我国SCI、EI期源刊有关石墨烯研究873篇，石墨烯研究的有关翻译存在很大差异。
从石墨烯的发现史及简介，谈石墨烯内涵及研究的相关翻译。
指出“石墨烯”有关术语翻译、英文题目、摘要撰写应注意的问题。
关键词：石墨烯；石墨烯术语；翻译石墨烯是目前发现的唯一存在的二维自由态原子晶体，它是构筑零维富勒烯、一维碳纳米管、三维体相石墨等sp2杂化碳的基本结构单元，具有很多奇异的电子及机械性能。
因而吸引了化学、材料等其他领域科学家的高度关注。
近5年我国SCI、EI期源刊研究论文873篇，论文质量良莠不齐，发表的论文有35.97%尚未被引用过，占国际论文被引的4.84%左右。
石墨烯研究的有关翻译也存在很大差异。
为了更好的进行国际学术交流，规范化专业术语。
本文就“graphene”的内涵及翻译谈以下看法。
l “Graphene”的发现史及简介1962年，Boehm等人在电镜上观察到了数层甚至单层石墨（氧化物）的存在，1975年van Bom-mel等人报道少层石墨片的外延生长研究，1999年德克萨斯大学奥斯汀分校的R Ruoff等人对用透明胶带从块体石墨剥离薄层石墨片的尝试进行相关报道。
2004年曼彻斯特大学的Novoselov和Geim小组以石墨为原料，通过微机械力剥离法得到一系列叫作二维原子晶体的新材料——石墨烯，并于10月22日在Sclence期刊上发表有关少层乃至单层石墨片的独特电学性质的文章，2010年Gelm和No-voselov获得了诺贝尔物理学奖。
石墨烯有着巨大的比表面积（2630 m2/g）、极高的杨氏模量（1.06 TPa）和断裂应力（～130GPa）、超高电导率（～106 S/cm）和热导率（5000W/m·K）。
石墨烯中的载流子迁移率远高于传统的硅材料，室温下载流子的本征迁移率高达200000 cm2/V.s），而典型的硅场效应晶体管的电子迁移率仅约1000 cm2/V.s。
毕业论文外文翻译-负载银的掺氮石墨烯概论
学号：10401604常州大学毕业设计（论文）外文翻译（2014届）外文题目Easy synthesis of nitrogen-doped graphene–silvernanoparticle hybrids by thermal treatment ofgraphiteoxide with glycine and silver nitrate 译文题目通过水热处理氧化石墨烯、甘氨酸和硝酸银简便地合成掺氮石墨烯-银纳米粒子复合物外文出处CARBON50(2012)5148–5155学生王冰学院石油化工学院专业班级化工106校内指导教师罗士平专业技术职务副教授校外指导老师专业技术职务二○一四年二月通过水热处理氧化石墨烯、甘氨酸和硝酸银简便地合成氮杂石墨烯-银纳米粒子杂合物Sundar Mayavan,Jun-Bo Sim,Sung-Min Choi摘要：氮杂石墨烯-银纳米粒子杂合物在500℃通过水热处理氧化石墨烯（GO）、甘氨酸和硝酸银制得。
甘氨酸用于还原硝酸根离子，甘氨酸和硝酸根混合物在大约200℃分解。
分解的产物可作为掺杂氮的来源。
水热处理GO、甘氨酸和硝酸银混合物在100℃可形成银纳米粒子，200℃时GO还原，300℃时产生吡咯型掺氮石墨烯，500℃时生成吡咯型掺氮石墨烯。
合成物质中氮原子所占百分比为13.5%.在合成各种纳米金属粒子修饰的氮杂石墨烯方面，该合成方法可能开辟了一个新的路径，其在能量储存和能量转换设备方面很有应用价值。
1.引言石墨烯是所有石墨材料的基本构件，其蜂窝状晶格由单层碳原子排列而成。
它表现出与结构有关的独特电子、机械和化学性质，具有较高的比表面积（2630-2965m2g-1）[1–3]。
化学掺杂杂原子石墨烯像掺杂氮原子，极大地引起了人们的兴趣，因其在传感器、燃料电池的催化剂和锂离子电池的电极等方面具有应用潜力[4–6]。
氮原子的掺杂改变了石墨烯的电子特性和结构特性，导致其电子移动性更强，产生更多的表面缺位。
Layer-by-Layer Assembly of Ultrathin Composite Films
Layer-by-Layer Assembly of Ultrathin Composite Films from Micron-Sized Graphite Oxide Sheets andPolycationsNina I.Kovtyukhova,*,†Patricia J.Ollivier,‡Benjamin R.Martin,‡Thomas E.Mallouk,*,‡Sergey A.Chizhik,§Eugenia V.Buzaneva,|andAlexandr D.Gorchinskiy|Institute of Surface Chemistry,National Academy of Sciences of Ukraine,31,Pr.Nauky, 252022Kyiv,Ukraine;Department of Chemistry,The Pennsylvania State University, University Park,Pennsylvania16802;Metal-Polymer Research Institute,32A Kirov Street, Gomel,246652,Belarus;and National T.Shevchenko University,64,Vladimirskaya Str.,252033Kyiv,UkraineReceived November24,1998.Revised Manuscript Received December28,1998Unilamellar colloids of graphite oxide(GO)were prepared from natural graphite and were grown as monolayer and multilayer thin films on cationic surfaces by electrostatic self-assembly.The multilayer films were grown by alternate adsorption of anionic GO sheets and cationic poly(allylamine hydrochloride)(PAH).The monolayer films consisted of11-14Åthick GO sheets,with lateral dimensions between150nm and9µm.Silicon substrates primed with amine monolayers gave partial GO monolayers,but surfaces primed with Al13O4-(OH)24(H2O)127+ions gave densely tiled films that covered approximately90%of the surface. When alkaline GO colloids were used,the monolayer assembly process selected the largest sheets(from900nm to9µm)from the suspension.In this case,many of the flexible sheets appeared folded in AFM images.Multilayer(GO/PAH)n films were invariably thicker than expected from the individual thicknesses of the sheets and the polymer monolayers,and this behavior is also attributed to folding of the sheets.Multilayer(GO/PAH)n and(GO/ polyaniline)n films grown between indium-tin oxide and Pt electrodes show diodelike behavior,and higher currents are observed with the conductive polyaniline-containing films. The resisitivity of these films is decreased,as expected,by partial reduction of GO to carbon.IntroductionThe assembly of composite thin films from lamellar inorganic particles and organic macromolecules is an inexpensive and versatile route to functional nanometer-scale structures.1These films are grown by a wet chemical,layer-by-layer adsorption method,which is similar to that developed earlier by Decher and co-workers for organic polyelectrolytes.2The addition of inorganic components offers the possibility of added optical,electronic,magnetic,mechanical,and thermal properties that may be difficult to achieve by using organic polymers alone.Additionally,the continuous inorganic sheets provide a barrier to interpenetration of sequentially deposited polymer or nanoparticle layers, a feature that can be important in thin films intended to act as current rectifiers,photodiodes,or Coulomb blockade devices.Several electronic and photonic ap-plications along these lines have established the utility of this method.3The layer-by-layer assembly method relies on the exfoliation of solids to produce colloids of sheets,which typically have nanometer thicknesses and lateral di-mensions of tens of nanometers to microns.Exfoliation procedures based on ion exchange and redox reactions have been developed for a variety of lamellar solids.4 Thus,multilayer inorganic/organic films have been grown from lamellar metal phosphates,titanates,nio-bates,5silicates,1b and metal chalcogenides,6compounds which in bulk form possess transport properties ranging from insulating to semimetallic.Recently,Fendler and co-workers have shown that such films can also be†National Academy of Sciences of Ukraine.‡The Pennsylvania State University.§Metal-Polymer Research Institute.|National T.Shevchenko University.(1)(a)Iler,R.K.J.Colloid Interface Sci.1966,21,569.(b)Kleinfeld,E.R.;Ferguson,G.S.Science1994,265,370.(c)Fendler,J.H.; Meldrum,F.Adv.Mater.1995,7,607.(d)Mallouk,T.E.;Kim,H.-N.; Ollivier,P.J.;Keller,S.W.In Comprehensive Supramolecular Chemistry;Alberti,G.,Bein,T.,Eds.;Elsevier Science;Oxford,UK, 1996;Vol.7,pp189-218.(2)Decher,G.Science1997,277,1232.(3)(a)Kaschak,D.M.;Mallouk,T.E.J.Am.Chem.Soc.1996,118, 4222.(b)Feldheim,D.L.;Grabar,K.C.;Natan,M.J.;Mallouk,T.E. J.Am.Chem.Soc.1996,118,7640.(c)Keller,S.W.;Johnson,S.A.; Yonemoto,E.H.;Brigham,E.S.;Mallouk,T.E.J.Am.Chem.Soc. 1995,117,12879.(d)Cassagneau,T.;Mallouk,T.E.;Fendler,J.H.J. Am.Chem.Soc.1998,120,7848.(4)(a)Jacobson,A.J.Mater.Sci.Forum1994,152-153,1.(b) Jacobson,A.J.In Comprehensive Supramolecular Chemistry;Alberti, G.,Bein,T.,Eds.;Elsevier Science;Oxford,UK,1996;Vol.7,pp315-335.(5)(a)Keller,S.W.;Kim,H.-N.;Mallouk,T.E.J.Am.Chem.Soc. 1994,116,8817.(b)Fang,M.,Kim,C.-H.;Saupe,G.B.;Kim,H.-N.; Waraksa,C.C.;Miwa,T.;Fujishima,A.;Mallouk,T.E.Submitted to Chem.Mater.(6)Ollivier,P.J.;Kovtyukhova,N.I.;Keller,S.W.;Mallouk,T.E. J.Chem.Soc.,mun.1998,1563.771Chem.Mater.1999,11,771-77810.1021/cm981085u CCC:$18.00©1999American Chemical SocietyPublished on Web01/28/1999grown from graphite oxide(GO),7which can subse-quently be reduced electrochemically to make electroni-cally conducting graphitic films.In their work,GO nanoparticles were prepared from synthetic graphite. They noted that the multilayer films consisted of incompletely exfoliated platelets that were tens of nanometers in their lateral dimensions.In this paper, we revisit the assembly of GO/polycation thin films, using GO prepared from natural crystals.We show that exfoliated GO derived from these crystals is a mechani-cally robust material that deposits conformally on cationic surfaces as micron-sized,nanometer-thick sheets. Graphite oxide is a pseudo-two-dimensional solid in bulk form,with strong covalent bonding within the layers.Weak interlayer contacts are made by hydrogen bonds between intercalated water molecules.8-11The carbon sheets in GO contain embedded hydroxyl and carbonyl groups,as well as carboxyl groups situated mainly at the edges of the sheets.8,9,12While there is no consensus as to the precise structure of GO layers, different structural models,9a,b,10which correspond to an ideal formula of C8O2(OH)2,have been advanced.A recent study of the structure of GO argues from13C and 1H NMR evidence for the presence of epoxy groups.13 Nakajima and co-workers have proposed that the carbon layers in GO are linked together in pairs by sp3C-C bonds perpendicular to the sheets.10According to Kli-nowski et al.,13the carbon layers in GO contain two kinds of domains,aromatic regions with unoxidized benzene rings and aliphatic regions with six-membered carbon rings.The relative size of the domains,which are randomly distributed,depends on the degree of oxidation.In both models,the hydroxyl groups project above and below the carbon grid.The phenolic hydroxyl groups are acidic and,together with the carboxyl groups, are responsible for the negative charge on the GO sheets in aqueous suspensions.9,13The surface charge density of colloidal GO particles(degree of oxidation85%)was measured by Fendler and co-workers as0.4per100Å2.7 The GO interlayer distance is not constant and depends strongly on the GO:H2O ratio.8-10,15In very dilute aqueous suspensions,the interlayer distance is large,so interaction between the layers is sufficiently weak that exfoliation occurs.8Our previous research showed that the number of layers in the GO colloidal particles can be controlled by the dilution of the suspen-sions.16,17The adsorption capacity for Cu(II)ions,which was for both aqueous suspensions16and thin films deposited from these suspensions on powder supports (ZnO,Al2O3,fumed SiO2),17increased with decreasing GO concentration in the starting suspension.For ex-ample,the adsorption capacity of GO films on SiO2 increased by a factor of2.4when the GO concentration in the starting suspension was decreased from1.0to 0.3g/L.This result shows that more complete exfoliation provides increased access to the GO functional groups. For samples prepared from the colloids with GO con-centrations of0.02-0.3g/L,the maximum adsorption capacity,22-24mmol/g,was obtained.This value is close to the total quantity of oxygen-containing groups in GO(25mmol/g9)and gives indirect evidence that dilute GO colloids are exfoliated as monolayers.We report here a detailed study of the preparation and characterization of GO/polycation films grown on planar Si and Al2O3/Al ing atomic force microscopy(AFM),ellipsometry,and electrical mea-surements,the following questions have been addressed: What does the first layer of the sheets adsorbed on a substrate look like microscopically?Can we affect the quality of mono-and multilayer films by varying the conditions of their deposition and the chemical composition of the substrate surface? What are the electronic properties of GO/polycation films,and how are they influenced by the nature of the polycation?Experimental SectionMaterials.GO was synthesized from natural graphite powder(325mesh,GAK-2,Ukraine)by the method of Hum-mers and Offeman.18It was found that,prior to the GO preparation according to ref18,an additional graphite oxida-tion procedure was needed.Otherwise,incompletely oxidized graphite-core/GO-shell particles were always observed in the final product.The graphite powder(20g)was put into an80°C solution of concentrated H2SO4(30mL),K2S2O8(10g),and P2O5(10g).The resultant dark blue mixture was thermally isolated and allowed to cool to room temperature over a period of6h.The mixture was then carefully diluted with distilled water,filtered,and washed on the filter until the rinse water pH became neutral.The product was dried in air at ambient temperature overnight.This preoxidized graphite was then subjected to oxidation by Hummers’method.The oxidized graphite powder(20g)was put into cold(0°C)concentrated H2SO4(460mL).KMnO4(60g)was added gradually with stirring and cooling,so that the temperature of the mixture was not allowed to reach20°C.The mixture was then stirred at35°C for2h,and distilled water(920mL)was added.In 15min,the reaction was terminated by the addition of a large amount of distilled water(2.8L)and30%H2O2solution(50 mL),after which the color of the mixture changed to bright yellow.The mixture was filtered and washed with1:10HCl solution(5L)in order to remove metal ions.The GO product was suspended in distilled water to give a viscous,brown,2% dispersion,which was subjected to dialysis to completely remove metal ions and acids.The resulting0.5%w/v GO dispersion,which is stable for a period of years,was used to prepare exfoliated GO.Exfoliation was achieved by dilution of the0.5%GO disper-sion(1mL)with deionized water(24mL),followed by15min sonication.The resulting homogeneous yellow-brown sol, which contained0.2g/L GO,was stable for a period of months and was used for film preparation.An aqueous solution(0.01M)of poly(allylamine hydrochlo-ride),PAH,(Aldrich,MW)50000-65000)was adjusted to pH7with NH3and was used for growth of polycation layers.(7)(a)Kotov,N.A.;Dekany,I.;Fendler,J.H.Adv.Mater.1996,8,637.(b)Cassagneau,T.;Fendler,J.H.Adv.Mater.1998,10,877.(8)(a)Thiele,H.Kolloid-Z1948,111,15.(b)Croft,R.C.Quart.Rev.1960,14,1.(9)(a)Scholz,W.;Boehm,H.P.Z.Anorg.Allg.Chem.1969,369,327.(b)Clauss,A.;Boehm,H.P.;Hofmann,U.Z.Anorg.Allg.Chem.1957,291,205.(10)Nakajima,T.;Mabuchi,A.;Hagiwara,R.Carbon1988,26,357.(11)Karpenko,G.;Turov,V.;Kovtyukhova,N.;Bakai,E.;Chuiko,A.Theor.Exp.Chem.(Russ.)1990,1,102.(12)Hadzi,D.;Novak,A.Trans.Faraday.Soc.1955,51,1614.(13)Lerf,A.;He,H.;Forster,M.;Klinowski,J.J.Phys.Chem.B1998,102,4477.(14)Hennig,Z.Progr.Inorg.Chem.1959,1,125.(15)Lagow,R.J.;Badachhape,R.B.;Wood,J.L.;Margrave,J.L.J.Chem.Soc.Dalton1974,1268.(16)Kovtjukhova,N.I.;Karpenko,G.A.Mater.Sci.Forum1992,91-93,219.(17)(a)Kovtyukhova,N.I.;Chuiko,A.A.Abstracts;Fall Meetingof the Materials Research Society,1994,Boston,C9.6.(b)Kovtyukhova,N.I.;Buzaneva,E.V.;Senkevich,A.Carbon1998,36,549.(18)Hummers,W.;Offeman,R.J.Am.Chem.Soc.1958,80,1339. 772Chem.Mater.,Vol.11,No.3,1999Kovtyukhova et al.An aqueous solution of doped polyaniline(PAN)was made from a saturated solution of the emeraldine base form in dimethylformamide.A3mL portion of this solution was slowly added with stirring to26mL of water,which had been acidified to pH3.5with aqueous HCl.The pH of the final PAN solution was then adjusted to2.5by addition of aqueous HCl.The alu-minum Keggin ion Al13O4(OH)24(H2O)127+was prepared trom Al13O4(OH)25(H2O)11(SO4)3‚x(H2O),which was available from a previous study.5Briefly,0.102g of the sulfate salt was added to a solution of0.042g of BaCl2in200mL of water and stirred overnight.The resulting0.3mM solution of the chloride salt of the aluminum Keggin ion was filtered using a0.2µm filter.Polished(100)Si wafers were sonicated in CCl4for15min and then rinsed with2-propanol and water.Their surface was then hydroxylated by30min sonication in“piranha”solution (4:1concentrated H2SO4:30%H2O2)(CAUTION:piranha solution reacts violently with organic compounds!)and was rinsed sequentially with water,methanol,and1:1methanol/ toluene before the surface derivitization steps began.Aluminum foil,Al-coated glass,both bearing a native oxide, and ITO glass were cleaned by washing with hexane for15 min prior to GO adsorption.Multilayer GO/PAH Film Growth.Hydroxylated silicon wafers were primed with one of three different types of cationic monolayers in order to initiate the growth of the GO films. This was achieved either by(1)reacting with4-((dimethyl-methoxy)silyl)butylamine(15h treatment with a5%toluene solution under dry Ar,over KOH at ambient temperature)or by(2)adsorbing a monolayer of aluminum Keggin ions(5min adsorption from aqueous solution of the chloride salt at80°C19) or by(3)adsorbing PAH(15min adsorption from a0.01M aqueous solution at pH7and ambient temperature).The primed Si substrates(1,2,and3)are designated hereafter as Si(NH2),Si(OH)/Al-Kg,and Si(OH)/PAH,respectively.The primed substrates were immersed in an aqueous(pH 5)or aqueous ammonia(pH9)GO sol(0.2g/L)for15min and then rinsed with deionized water and dried in flowing Ar.The samples were then immersed in aqueous PAH solutions for 15min,rinsed with deionized water,and dried in flowing Ar. Multilayer GO/PAH films were grown by repeating these adsorption cycles.Preliminary experiments had shown that the thickness of a deposited layer(estimated by ellipsometry) does not depend on the substrate/solution contact time in the range from2min to2h.For electronic measurements, multilayer(GO/PAH)14and(GO/PAN)30films were grown on ITO in similar adsorption cycles.For comparison purposes,a GO colloid film(ca.90nm thick)was prepared by dip-coating the ITO/glass in the GO colloidal dispersion.Characterization.Atomic force microscopy(AFM)images of the layers deposited on Si substrates were obtained with a Digital Instruments Nanoscope IIIa in tapping mode,using a 3045JVW piezo tube scanner.The125µm etched Si cantile-vers had a resonant frequency between250and325kHz,and the oscillation frequency for scanning was set to∼0.1-3kHz below resonance.Typical images were obtained with line scan rates of2Hz while256×256pixel samples were collected.Ellipsometric measurements were made with a Gaertner model L2W26D ellipsometer.An analyzing wavelength of632 nm was used,because GO absorbs minimally at this wave-length.The incident angle was70°and the polarizer was set at45°.Ellipsometric parameters were measured following each GO or PAH adsorption step.Si substrates were dried in an Ar stream before each measurement.The film thickness of the GO/PAH multilayers was calculated using the Si refractive indices,n s)3.875and k s)-0.018,determined from a blank sample.The refractive index of GO/PAH films was estimated as n f)1.540,k f)0.Transmission electron microscope(TEM)images were ob-tained with a JEOL1200EXII microscope at120kV ac-celerating voltage.Samples were prepared by immersing a copper grid in the GO sol and drying in air.The elemental composition of GO was determined by using a home-built mass spectrometer with laser probe(LMS).The diameter of the crater for single laser impulse was0.42-0.48 mm,and the depth was1µm.IR spectra were recorded using a Perkin-Elmer325instrument.XPS spectra were obtained using a Kratos Series800spectrometer with hν)1253.6eV and an analyzing window of4×6mm2.The accuracy of the measured core level binding energies(E b)was0.1eV.For LMS, IR,and XPS experiments,GO samples were prepared as films by drying a droplet of the sol in air at ambient temperature. X-ray powder diffraction(XRD)patterns were recorded with a DRON-1instrument using Cu K R radiation.Prior to the measurement,the GO sample was dried in a vacuum over P2O5 for24h.Electrical measurements of films deposited on ITO glass were carried out using top Pt electrode contacts that were10µm in diameter and mechanically pressed into the film,usinga home-built parametric analyzer.The sensitivity of current measurements was0.01nA.All measurements were carried out in air at ambient temperature.The turn-on potential for all thin film devices studied was taken as the potential at which a current of1.0nA was observed.In regions where current was more than3nA,every step of voltage increase (typically0.1mV in both the forward and reversed directions) was followed by repeating the measurement cycle to ensure the reproducibility of the current measured at the lower voltage.Measurements were considered irreversible(i.e.,a permanent change to a more conductive state occurred)when the current recorded the second time at the lower voltage was noticeably higher than that measured in the previous cycle.Results and Discussion Characterization of the GO Colloid.The XRD pattern of GO prepared by preoxidation with persulfate followed by oxidation with permanganate reveals a sharp002reflection at2θ)12.80°,which corresponds to a c-axis spacing of6.91ÅThis value falls within the range of6.3-7.7Åreported in the literature9a,10,20,21for GO prepared from natural graphite according to Hum-mers’method.18No002diffraction peak from unreacted graphite(d)3.35Å)is observable in the XRD pattern. The IR spectrum of GO prepared by this method is essentially identical to that reported in the litera-ture.9a,12,21A band at3420cm-1and a broad band centered around3220cm-1are attributed to O-H stretching vibrations of the C-OH groups and water, respectively;a band at1730cm-1is assigned to C d O stretching vibrations of the carbonyl and carboxyl groups.Bands at1365,1425,and1615cm-1are assigned to the O-H deformations of C-OH groups and water,respectively.A band at1080cm-1is due to C-O stretching vibrations.Deconvolution of the C1s peak in the XPS spectrum shows the presence of four types of carbon bonds:C-C (284.8eV),C-O(286.2eV),C d O(287.7eV),and O-C d O(288.5eV).By integrating the area of the deconvolu-tion peaks,the following approximate percentages were obtained:C-C,49.5;C-O,31.4;C d O,9.1;O-C d O, 2.9.The LMS spectrum of GO prepared by this method gave the following atomic composition(wt%):H,2.3; C,45.2;O,46.5;P,3.3;K,2.7;C:O ratio)1.3.The same or nearly the same C:O ratio has been found previously for GO samples prepared from natural graphite.21,22It is generally accepted that the conversion of graphite to(19)Schoenherr,S.;Goerz,G.;Mueller,D.;Gessner,W.Z.Anorg. Allg.Chem.1981,476,188.(20)Carr,K.E.Carbon1970,8,245.(21)Kyotani,T.;Suzuki,K.;Yamashita,H.;Tomita,A.Tanso1993, 160,255.(22)Slabaugh,W.H.;Seiler,B.C.J.Phys.Chem.1962,66,396.Assembly of Ultrathin Composite Films Chem.Mater.,Vol.11,No.3,1999773GO is complete when the C:O ratio becomes 2.0.The observed ratio C:O:H )4:3.1:2.5is richer in O and H than that calculated for C 8O 2(OH)2:4:2:1;this can be explained by the presence of intercalated/adsorbed water and carboxyl groups,as shown by IR and XPS.It should be noted that the ideal formulation does not take into account the presence of carboxyl groups,which are mainly situated on the edges of the sheets,8or interca-lated water,some amount of which is probably an integral part of the GO structure.3Allowing that 2.9%of the carbon atoms are present as carboxyl groups (from XPS)and assuming that the potassium ions are incor-porated by ion-exchange,we calculate a formula of C 3.77O 2.05H 0.92K 0.07‚0.73H 2O,or C 8O 2.25(OH)1.95(OK)0.15‚1.55H 2O,which gives a C:O:H ratio of 4:2.95:2.5.The remaining oxygen (2.05wt %)is most probably bound to phosphorus,an impurity introduced by the graphite preoxidation step.TEM images of the GO sol (Figure 1)reveal flexible,wrinkled sheets of different lateral sizes ranging from hundreds to thousands of nanometers.Flexible GO particles were also observed by Hennig and Carr.14,20No graphite particles are observed in these images.AFM Images of the First Adsorbed GO Layer.Si Substrates.AFM images (Figure 2a -c)of the GO films deposited in one adsorption cycle from aqueous solution show surface coverages of about 30%for Si(NH 2),85%for Si(OH)/PAH,and 90%for Si(OH)/Al-Kg substrates.The main features are 150-900-nm-wide islands,whose size is close to that determined by TEM for the GO sheets.In some cases,corrugations and the turned-in edges of the sheets are seen.For the PAH-primed Si substrate,the average roughness of the sheet-coveredpart of the surface is 4.5ÅBy comparison,the rough-ness of the Si(OH)/PAH substrate was 6.2-Å,indicating slight smoothing of the surface by the GO monolayer.The height of the islands on Si(NH 2)and Si(OH)/PAH,10.6-14.1Å,and the average roughness of their surface,3.9-4.5Å,are consistent with exposure of GO basal planes covered by adsorbed H 2O.8-10Ellipsometric measurements gave 11and 14Åthicknesses for GO monolayers on Si(NH 2)and Si(OH)/PAH.Considering that the thickess of the priming layer is about 7Å,and that the GO sheets cover only part of the surface,these results are in reasonable agreement with the island heights measured by AFM.According to Nakajima’s structural model,10the thick-ness of a GO monolayer depends on the content of hydroxyl groups on its basal planes and can reach 8.2Åfor the completely hydroxylated monolayer.Assuming the presence of completely hydroxylated GO carbon layers in very dilute colloids,one can take the thickness of a GO monolayer as 8.2Å.By comparing this value with the height of the islands in Figure 2,one can conclude that the islands consist of a single GO sheet covered by a layer of adsorbed water molecules.The thickness of doubled GO layers can be estimated from the thickness of two GO monolayers,2×8.2Å,plus the distance between the layers,which is determined by the thickness of the layer of weakly bound mobile water molecules.11,13This interlayer distance can be estimated at about 3Å,from the repeat distance along the c -axis of well-hydrated GO samples,I c )11Å,9,14minus the thickness of a GO monolayer,8.2Å.This means the thickness of doubled GO layers should be about 20Åor more,if water adsorbed onto the top basal plane is considered.This value is significantly greater than the height of adsorbed islands (10.6-14.1Å).The height,20.1Å,of the GO islands adsorbed onto the Al-Keggin-primed Si surface (Figure 2b)is roughly consis-tent with the thickness of the Al-Keggin anchoring layer (7Å23)and a monolayer of GO sheets covered by adsorbed H 2O (10.6-14.1Å).An AFM image of the first GO layer adsorbed from an aqueous ammonia suspension (pH 9)onto a Si(NH 2)substrate is shown in Figure 2d.In this case,the adsorption process selects much larger sheets (900-9000nm)which cover about 60-65%area of the surface.The dissociation of the GO hydroxyl groups (situated mainly on the basal planes)occurs around pH 9and significantly increases the negative charge density on the GO sheets.The increased attraction of the sheets for the cationic surface results in higher coverage than that observed at lower pH.This interaction is appar-ently more effective for the larger sheets,which can bridge over neutral regions of the incompletely primed surface.Previous studies have shown that the amine priming layer does not completely cover the surface,and that it is only partially protonated at pH 9.5The average roughness of the sheets on the surface is 4.4Å.The height of the sheets,which are corrugated and some-times have turned-in edges,is in the range of 19-23Å.The increased thickness may be due to a hydrated layer of charge-compensating NH 4+ions,which cover the basal plane surface.The adsorption of a bilayer of sheets(23)Johansson,G.;Lundgren,G.;Sillen,L.G.;Soderquist,R.Acta Chem.Scand.1960,14,769.Figure 1.Transmission electron micrograph of colloidal graphite oxide particles.774Chem.Mater.,Vol.11,No.3,1999Kovtyukhova et al.seems unlikely,since in basic media the exfoliation of GO occurs more readily.8Al 2O 3/Al Substrates.AFM images of the first GO layer grown on Al-coated glass (Figure 3a)and alumi-num foil (not shown)resemble those of the substrates,except that corrugations similar to those seen in the TEM image of GO and AFM images of the GO/Si have appeared.Because both Al 2O 3/Al substrates are very rough and because the flexible GO sheets conform to the surface,it is not possible to determine the lateral and vertical dimensions of the sheets.However,the average roughness of the brighter area in the image,which is presumed to have an adsorbed GO sheet,is 2.7nm.By comparison,the substrate roughness is 3.5-nm,again indicating a slight smoothing of the surface by the GO sheets.Characterization of GO/PAH Multilayers.Ellipsometry.Figure 4shows plots of film thickness,determined by ellipsometry,versus the number of adsorption cycles for GO/PAH multilayer films.The films were grown on Si(NH 2),Si(OH)/PAH,and Si(OH)/Al-Kg substrates.The linearity of the filmthicknessFigure 2.Tapping-mode AFM images of the first graphite oxide layer deposited from aqueous and aqueous ammonia sols on primed Si substrates:(a)Si(NH 2),GO sol pH 5,with the linescan showing the apparent height of sheet (14Å)above the background;(b)Si(OH)/Al-Kg,GO sol pH 5;(c)Si(OH)/PAH,GO sol pH 5;and (d)Si(NH 2),GO sol pH 9.Assembly of Ultrathin Composite Films Chem.Mater.,Vol.11,No.3,1999775plots indicates that on average the same amount of material is deposited in each adsorption cycle.However,for each the sample,the average increase in layer thickness per PAH/GO bilayer is different and ranges from 29to 50Å(Table 1).The lowest value,29Åper PAH/GO bilayer,is found for GO grown from aqueous ammonia solution (pH 9).The smaller layer pair thick-ness in this case may arise from partial deprotonation of the underlying PAH layer at this pH.Because thesurface charge density is lower,fewer anionic sheets are bound by the polymer per unit area.It should be noted that the measured thickness of the GO/PAH layer pair (40-50Å)is more than that expected from the thickness of monolayer GO sheets (10.6-14.1Å,as estimated by AFM for the first depos-ited GO layer,Figure 2a -c)and the thickness of single PAH layer (5Å24).This can be explained in part by folding of the flexible GO sheets,which is apparent in the AFM images of all GO monolayers except the low coverage layer grown on Si(NH 2).The multilayer ad-sorption model proposed by Kleinfeld and Ferguson for clay/polycation films 1b may also be operative for GO/PAH.In their model,each adsorption cycle deposits about two layers of polyelectrolyte,but they rearrange (possibly by folding in the present case)into alternating single sheet/polycation films.A plot of the thickness of a GO/PAH film grown from aqueous solution onto Si(NH 2)is linear only after the third cycle.The average increase in thickness per PAH/GO bilayer is 23Åin the first two adsorption cycles and 49Åin the following three adsorption cycles (Figure 4).This behavior is reminiscent of that observed by Kleinfeld and Ferguson for clay/polycation films,which nucleate in islands and completely cover the surface only after several adsorption cycles.25We conclude that the GO/PAH film coverage is relatively complete after adsorption of the second bilayer (the first adsorption cycle covers ∼30%of the surface;Figure 2a).In subse-quent adsorption cycles,the layer pair thickness is close to that found for GO/PAH multilayers on Si(OH)/PAH.In the latter case,the surface coverage is ∼85%after the first adsorption cycle,as shown in Figure 2c.AFM.AFM images of four or five bilayer GO/PAH films on all three substrates were similar and did not clearly resolve the sheet edges or the voids between sheets.From these images,one can only conclude that the multilayer films completely cover the surface.Figure 3b shows a typical image of a Si(OH)/Al-Kg /(GO/PAH)3GO film.The average roughness of this film is 20Å,which is consistent with a surface of loosely tiled and folded sheets.Multilayer film roughness and thick-ness parameters,determined by AFM and ellipsometry,respectively,are summarized in Table 1.For all the substrates under investigation (except for very rough aluminum foil),GO/PAH multilayers depos-ited from aqueous sols on Al(OH)x -terminated surfaces (Si(OH)/Al-Kg and Al/Al 2O 3)are smoother than those deposited on NH 2-terminated surfaces (Si(NH 2)and Si-(OH)/PAH)(Table 1).Comparing the surface morphol-ogies of the first GO layer and the multilayer films,one can see that the more densely tiled first layer (∼90%,Figure 2b),grown on the Keggin-primed surface,yields a smoother and more compact multilayer film,whereas the poorly tiled first layer (∼35%,Figure 2a)on Si(NH 2)yields the roughest multilayer surface.Again,this behavior is consistent with the model proposed by Kleinfeld and Ferguson for multilayer growth on is-lands,which eventually coalesce into smoother films.25(24)(a)Lvov,Yu.;Haas,H.;Decher,G.;Mohwald,H.;Kalachev,A.J.Phys.Chem.1993,97,12835.(b)Lvov,Yu.;Decher,G.;Mohwald,ngmuir 1993,9,481,(c)Decher,G.;Hong,J.;Schmitt,J.Thin Solid Films 1992,210/211.(25)Kleinfeld,E.R.;Ferguson,G.R.Chem.Mater.1996,8,1575.Figure 3.(a)Tapping-mode AFM image of the first graphite oxide layer deposited from the aqueous sol onto Al-coated glass and (b)image of a (GO/PAH)3GO film on Si(OH)/Al-Kg.Z range is 15nm in bothimages.Figure 4.Ellipsometric measurements of the thickness of multilayer GO/PAH films vs number of adsorption cycles:1,Si(OH)/PAH(GO/PAH)n GO;2,Si(OH)/Al-Kg(GO/PAH)n GO;3,Si(NH 2)(GO/PAH)n GO;4,Si(NH 2)(GO/PAH)n GO (pH 9).The thicknesses at an abscissa value of 0.5correspond to primer cationic layers;points on the plots refer to films terminated by a GO layer.776Chem.Mater.,Vol.11,No.3,1999Kovtyukhova et al.。
Graphene Corrosion--InhibitingCoating 简介及翻译
Graphene: Corrosion-InhibitingCoating石墨烯：防腐蚀涂层研究发表在美国化学学会（ACS）《纳米》（Nano）上石墨烯是一种从石墨材料中剥离出的单层碳原子面材料，是碳的二维结构，是一种“超级材料”，硬度超过钻石，同时又像橡胶一样可以伸展。
它的导电和导热性能超过任何铜线，重量几乎为零。
这种石墨晶体薄膜的厚度只有0.335纳米，把20万片薄膜叠加到一起，也只有一根头发丝那么厚。
Dhiraj Prasai,† Juan Carlos Tuberquia,§Robert R. Harl,§G. Kane Jennings,§and Kirill I. Bolotin‡,* Interdisciplinary Graduate Program（跨学科研究生课程）in Materials Science（材料科学）Department of Physics and Astronomy,物理和天文学Department of Chemical and Biomolecular Engineering,化学和生物分子工程学Vanderbilt University, Nashville, Tennessee 37235, United States范德比尔特大学（田纳西州州纳什维尔）37235美国范德比尔特大学是一所私立研究型大学，位于美国田纳西州纳什维尔。
学校成立于1873年，学校是以航运和铁路大亨“准将”科尼利厄斯范德比尔特的名字命名的，他提供范德比尔特一百万美元捐赠，尽管他从未到过南方，但希望他的捐赠能够帮助学校在抚平内战留下的创伤方面发挥更大的作用。
目前，范德比尔特大学包括4个本科学院和6个研究生学院，招收学生约12000多名，分别来自美国50个州和90多个国家。
在2009年的大学排名中，美国新闻与世界报道将范德比尔特排在国家大学的第18名，其中教育、法律、工程、医学、护理等几个学院在该国都跻身前20名。
石墨烯参考资料汇总
石墨烯参考资料汇总石墨烯，英文名Graphene，是从石墨材料中剥离出来的由碳原子组成的二维晶体，是目前已知世界上强度最高的材料。
2008年4月，英国科学家宣布他们用石墨烯制造出一种只有1个原子厚、10个原子宽的超微型晶体管，从而使石墨烯替代硅材料成为可能。
1、石墨烯 - 简介石墨烯石墨烯是一种从石墨材料中剥离出的单层碳原子面材料，是碳的二维结构。
这种石墨晶体薄膜的厚度只有0.335纳米，把20万片薄膜叠加到一起，也只有一根头发丝那么厚。
它是2004年由曼彻斯特大学的科斯提亚•诺沃谢夫和安德烈•盖姆小组首先发现的。
目前有三种方法制备石墨烯，一种是加热SiC的方法，另一种是轻微摩擦法或撕胶带法，第三种是化学分散法。
2、石墨烯 - 特性电子运输石墨烯结构示意图在发现石墨烯以前，大多数（如果不是所有的话）物理学家认为，热力学涨落不允许任何二维晶体在有限温度下存在。
所以，它的发现立即震撼了凝聚态物理界。
虽然理论和实验界都认为完美的二维结构无法在非绝对零度稳定存在，但是单层石墨烯在实验中被制备出来。
这些可能归结于石墨烯在纳米级别上的微观扭曲。
石墨烯还表现出了异常的整数量子霍尔行为。
其霍尔电导=2e²/h,6e²/h,10e²/h.... 为量子电导的奇数倍，且可以在室温下观测到。
这个行为已被科学家解释为“电子在石墨烯里遵守相对论量子力学，没有静质量”。
导电性石墨烯结构非常稳定，迄今为止，研究者仍未发现石墨烯中有碳原子缺失的情况。
石墨烯中各碳原子之间的连接非常柔韧，当施加外部机械力时，碳原子面就弯曲变形，从而使碳原子不必重新排列来适应外力，也就保持了结构稳定。
这种稳定的晶格结构使碳原子具有优异的导电性。
石墨烯中的电子在轨道中移动时，不会因晶格缺陷或引入外来原子而发生散射。
由于原子间作用力十分强，在常温下，即使周围碳原子发生挤撞，石墨烯中电子受到的干扰也非常小。
石墨烯最大的特性是其中电子的运动速度达到了光速的1/300，远远超过了电子在一般导体中的运动速度。
学生石墨烯文献翻译
石墨烯/聚合物纳米复合材料摘要：石墨烯由于其特殊的电导性、机械性能和大的表面积而具有巨大的科研价值，当加入适当时，这些原子薄碳层可以显著提高主要高聚物的物理性能。
我们首先按照从上到下的战略回顾一下从氧化石墨到石墨烯的生产工艺过程，包括每种方法的优点和缺点。
然后按溶解和熔融的战略即分散化学和加热的方法讨论降低氧化石墨在聚合物中的含量。
对于微粒大小的性质、表面性质和在基体中的离散性的技术分析也有介绍。
我们总结石墨烯/聚合物纳米复合材料的导电性、导热性、机械性能和阻气性。
我们结合石墨烯复合材料的加工和可量测性总结这些观点列出最近的挑战和这些新的纳米复合材料的远景。
1介绍基于炭黑、碳纳米管和层状硅酸盐的聚合物纳米复合材料被用于增强聚合物的机械性能、导电性、导热性和阻气性。
石墨烯极其特殊的物理性能和能溶于多种基本聚合物的结合的发现创造了一类新的聚合物纳米复合材料。
石墨烯是由sp2杂化的碳原子按蜂窝状结构排列成的单层、二维片状结构。
它被誉为其他所有不同维数的石墨碳的同素体的基础材料，例如，石墨（三维碳的同素体）由石墨烯的薄碳片正面向上堆积在一起并且分开距离为3.37A组成。
0维同素体，富勒烯（足球烯），可以想象成单层石墨烯的一部分卷曲成的。
一维碳同素体，碳纳米管和碳纳米带可以分别由单层石墨烯旋转和剪切制成。
实际上，然而，这些碳的同素体，除了碳纳米带，都不是由石墨烯合成的。
石墨是一种天然生成的材料，它最早的记载于1555年在英国的Borrowdale，但是它最早的应用可向前追溯4000年。
在1985年发现富勒烯后于1991年第一次合成单壁碳纳米管。
尽管生产石墨烯纳米片的第一个方法报道可以追溯到1970年，但对存在的单层石墨烯在2004年第一次被生产出来，用微机械剥离的方法从石墨中分离出石墨烯。
杨氏模量为1TPa和极限强度为130GPa，单层石墨烯为测量出来的最强的材料。
它的导热系数为5000W/cm3*KJ,与报道的碳纳米束最高值的上限相一致。
外文译文
用固态碳源生长石墨烯摘要：单层石墨烯作为一种可转移材料在2004年第一次被获得并且引起了物理学家、化学家、材料学家强烈地关注。
很多研究都致力于找到获得大面积单层或双层石墨烯的方法。
最近这种方法已经被找到，是通过在铜或镍基底上化学气象沉积（CVD）甲烷或乙炔。
但是CVD方法仅限于未加工的气体原料，而很难应用于更加广泛的潜在的原料。
在这里我们论证一种方法：利用固态碳源—比如聚合物薄膜或小分子，最低只要800℃就能够在金属触媒基底上生长出大面积、高质量、可控制厚度的石墨烯。
原始石墨烯和掺杂石墨烯都是用这种一步工序在同样的设备上生产的。
正文：石墨烯有着非凡的电学和机械性能在很多应用方面都表现出很好的前景。
现在有很多获得石墨烯的方法。
最原始的机械剥离法可以从高取向性的热分解石墨上获得少量高质量的石墨烯。
液体剥落并还原氧化了的石墨烯已经被用于化学转化获取大量石墨烯。
热处理SiC，用无定形碳和CVD方法已被应用在晶片上生长大尺寸石墨烯。
通过引进Ni和Cu作为CVD生长的基底，石墨烯的尺寸、厚度、质量正在接近工业化使用标准。
然而石墨烯本质上是零带隙材料表现出很弱的二极性；基于石墨烯的二极管表现出和低的“开／关”电流比，因此它们被用于电子器件设计时很像金属。
为了改变石墨烯的费米能级以及利用它的电学和光学属性，给石墨烯掺杂得到ｎ型，ｐ型或混合型掺杂石墨烯一直是我们奋斗的目标。
当前，用固态碳源在金属触媒基底上生长单层原始石墨烯已被论证（图１ａ）第一种被使用的固态碳源是旋涂的聚合物（聚甲基丙烯酸甲酯）（PMMA）薄膜（~100nm）,金属触媒基底是铜薄片。
在最低为800℃最高为1000℃（测试上限）的温度，伴随着还原性气流（H2/Ar）的低压条件下生长10分钟，单层一致的石墨烯就在基底上生成了。
因此石墨烯材料被成功的转移的不同的基底上有更多的特性（见Supplementary Materials and Supplem entary Methods）这种源于PMMA的单层石墨烯的拉曼光谱如图1b所示，这个光谱表征了样品1 cm2范围内大于10个位置的情况。
材料科学专业毕业设计外文文献及翻译
材料科学专业毕业设计外文文献及翻译文献摘要为了适应不断发展的材料科学领域，毕业设计需要参考一些权威的外文文献。
在这里，我们提供了一些与材料科学专业相关的外文文献，并附带简要翻译。
---文献1: "石墨烯在材料科学中的应用"作者: John Smith, Mary Johnson: John Smith, Mary Johnson摘要::本文综述了石墨烯在材料科学中的应用。
石墨烯是一种单层碳原子结构，具有独特的物理和化学性质。
我们讨论了石墨烯的制备方法、其在电子学、能源存储和生物医学领域中的应用。
石墨烯在材料科学中具有巨大的潜力，可以为未来的材料研究和应用开辟新的道路。
---文献2: "纳米材料的合成与性能研究"作者: David Brown, Emma Lee: David Brown, Emma Lee摘要::本文讨论了纳米材料的合成方法及其性能研究。
纳米材料是具有纳米尺度结构的材料，具有与宏观材料不同的性质。
我们介绍了几种常见的纳米材料合成方法，例如溶液法和气相法，并讨论了纳米材料的晶体结构、表面性质和力学性能。
研究纳米材料的性能对材料科学的发展和应用具有重要意义。
---文献3: "高温合金的热稳定性研究"作者: Jennifer Zhang, Michael Wang: Jennifer Zhang, Michael Wang摘要::本文研究了高温合金的热稳定性。
高温合金是一种用于高温环境的特殊材料，具有优异的耐热性能。
我们通过实验研究了高温合金的热膨胀性、热导率和高温力学性能。
通过了解高温合金的热稳定性，我们可以提高材料的耐高温性能，从而推动高温环境下的应用和工程技术发展。
---以上是几篇关于材料科学的外文文献摘要及简要翻译，希望对毕业设计的参考有所助益。
石墨烯 英文综述 论文
C-base Material Applied In Lithium Ion BatteryAbstractSince its first commercialization of the Li-ion battery from Sony Laboratories, Carbon-based rechargeable batteries have gained extensive attention, wherein metallic lithium is replaced by a carbon host structure that can reversibly absorb and release lithium ions at low electrochemical potentials. Thousands of scientific groups have taken Carbon-base material as the anode for the lithium ion battery. By critically analysing latest research papers, we aim to address the benefits and issues of Carbon materials, as well as outline the most promising results and applications so far.Keywords: Anode, Carbon-base material, Lithium Ion BatteryIntroductionThere is increasing worldwide demand for advanced Li ion batteries (LIBs) with higher energy capacity and longer cycle lifetime for applications in mobile communication devices, portable electronic devices, electrical/ hybrid vehicles, and miscellaneous power devices. Traditional highly graphitized carbon anode materials show low Li storage capacity (<372 mAh/g) due to limited Li ion storage sites within sp2 carbon hexahedrons. To go beyon d the “ion” site limitation, many studies have explored Carbon-based materials for higher electrochemical energy storage.As originally reported by Dahn et al. in 1995, an anode comprising single layers of graphene can host two times as many Li+ ions as conventional graphite. The storage of one lithium ion on each side of graphene results in a Li2C6 stoichiometry that provides a specific capacity of 744 mAh/g — twice that of graphite (372 mAh/g). Differently from graphite, in which lithium is intercalated between the stacked layers, single-layer graphene can theoretically store Li+ ions through an adsorption mechanism, both on its internal surfaces and in the empty nanopores that exist between the randomly arranged single layers. In other reported studies, reduced graphene oxide (RGO) is also a very promise substance for lithium-ion storage. During the first Li+ insertion, RGO exhibited incredibly high-capacity values of >2000 mAh/g, which is higher than the theoretical capacity of single-layer graphene. However, this amazing capacity is not fully released after de-insertion due to the massive irreversibility of the first lithiation step. This phenomenon, also observed for other Li-ion anode materials, can be attributed mainly to the irreversible reduction of the electrolyte to form a surface passivation layer on the active particles, namely, the solid electrolyte interphase.Owing to high conductivity and stability, C-based material can also be used to couple with other electroactive materials such as metal (or metal oxide) nanoparticles. These kind of composites provides reversible alloying (with SnO2 or Si nanoparticles), insertion (with TiO2) or conversion (with Fe2O3 or Co3O4) reactions with lithium, thus allowing considerably higher storage capacities. The extensive and highly conductive carbon matrix established by graphene layers improves the electrical conductivity of the composite and buffers eventual volume changes taking place in electrodes based on alloying or conversion materials during cycling.In this review, we critically analyze latest research papers and demonstrate C-base material can be used in different aspect in the electrochemistry field.Graphene as an active materialIn lithium-ion batteries (LIBs), Li+ ions continuously shuttle between a lithium-releasing cathode (commonly a layered lithium metal oxide) and a lithium-accepting anode (commonly graphite). The amount of ions hosted per gram of material determines the capacity — and thus the energy — of the battery. Similar to graphite, graphene can be used as an anode for hosting Li+, both as such and as a carbonaceous matrix in composites with other materials also capable of storing lithium.Graphene-prepared by different methodsGraphene nanosheets have significant disorder/defects, large specific surface area, and remaining surface functional groups. All these factors have ever been proposed to be related to additional Li storage capacity in nongraphite carbonaceous materials with high specific capacities. Dengyu Pan et al synthesize a highly disordered graphene nanosheet with an outstanding capacity of 794-1054 mAh/g. They prepare graphene nanosheets with different disorder level by changing reduction methods and conditions. A series of graphene nanosheet samples were prepared from graphene oxide (GO) sheets via three different routes including hydrazine reduction, pyrolytic deoxidation and electron beam irradiation.Figure 1 Raman spectra of four different reductionsRaman spectra with characteristic G and D bands sensitive to defects, disorder, and carbon grain size have extensively been used to characterize carbon materials. The G band arises from the zone center E2g mode, corresponding to ordered sp2 bonded carbon, whereas the D band is ascribed to edges, other defects, and disordered carbon. The I D/I G intensity ratio is a measure of disorder degree and average size of the sp2 domains. Figure 1 displays the Raman spectra of four different reduction samples. Figure 1b shows Electron Beam reduced GO has a I D/I G of 1.51 and Hydrazine Reduced GO has a smaller I D/I G of 0.74. Figure 1c displays the Raman spectra of the pristine and pyrolytic GO. For the 300℃pyrolytic GO, however, the G band disappears. The disappearance of the G band arises from the destruction of the E2g symmetry and structural distortion of sp2 domains induced by the low-temperature pyrolysis.Figure 2 shows reversible capability verse cycle Figure 2 Cycle performance number of above materials. (i) natural graphite (ii)pristine GO (iii) hydrazine-reduced GO (iv) 300℃pyrolytic GO (v) 600 ℃pyrolytic GO (vi) andelectron-beam-reduced GO. It can be easily to drawthe conclusion that the material with higher I D/I Gdisplays a better electrochemistry performance.They can correlate the reversible capacity with theRaman intensity ratio. That is, Raman intensityratio (I D/I G) may be the key structural parameter for evaluation of the reversible capacity. What is more, they propose a mechanism to explain how Raman intensity ratio is correlated with the reversible capacity. The I D/I G ratio describes disorder degree in carbonaceous materials because the D band is ascribed to disordered carbon, edge defects, and other defects.Scheme 1 The Li storage model of graphene nanosheetsThe Li storage model of graphene nanosheets is suggested in Scheme 1. The defects at the interface between the nanosheets and the electrolyte may accommodate irreversible Li present in SEI films, whereas the defects at edge sites and internal (basal-plane) defects (vacancies etc.) of the nanodomains embedded in graphene nanosheets may involve reversible Li storage because these defects do not come into contact with the electrolyte. Some Li ions may be stored reversibly between (002) planes, but the defect-based reversible storage may predominate. The notable capacity fading observed in the highly disordered samples may be ascribed to the disorder-induced structure instability.Graphene-doped by other elementsAnother method to improve defects and vacancies is to dope other elements to graphene. It is generally believe that lithium ion batteries (LIBs) using a bulk material such as layered graphite or metal oxide as an anode are capable of achieving a high energy density by storing charges in the bulk of the material, but suffer from a low power density compared to another important electrochemical storage device, electrochemical capacitors (ECs).In order to meet the requirements for LIB applications, Zhong-Shuai Wu et al synthesize the doped graphene electrodes with extremely high rate and large capacity made by heteroatom (N, B)- doped chemically derived graphene. At a low charge/discharge rate of 50 mA /g, the doped graphene electrodes exhibit a very high capacity of 1043 mAh/g for N-doped graphene and 1549 mAh/g for B-doped graphene with greatly improved Coulombic efficiency and cycle performance in comparison with undoped graphene. More importantly, the doped graphene can be quickly charged and discharged for a very short time of 1 h to several tens of seconds, showing high rate capability and excellent long-term cyclability at the same time.At a very high current rate of 25A /g (seen in Figure 3), corresponding to a charge time of28s (126C) for the N-doped graphene and 33s (106 C) for the B-doped graphene, the reversible capacity can still reach 199 mAh/g for the N-doped graphene and 235 mAh/g for the B-doped graphene.Figure 3 The rate performance of N-doped (c) and B-doped (d) graphene What’s more, these doped graphene sheets show a higher thermal stability of 531℃for the N-doped graphene and 588℃for the B-doped graphene than that of pristine graphene (502℃) due to the simultaneous doping and reduction during the doping process. The author suppose that improved electrical conductivity, and thermal stability of the doped graphene allow rapid surface Lit absorption and ultrafast Li+ diffusion and electron transport, thus making this material superior to conventional bulk electrode materials based on Li intercalation and conversion reactions. Graphene as an inactive materialLiCoO2, LiMn2O4 and LiFePO4 (hereafter referred to as LMO) are some of the most commonly used cathode materials in LIBs. The cycle life and rate capability of these materials are generally limited by their poor electrical conductivity. Introducing low-cost conductive additives (for example, carbon black) into the composite electrodes commonly solves this issue. Nevertheless, owing to their amorphous structure, carbon blacks possess a rather low electrical conductivity, with respect to more crystalline carbons such as graphene.Thousands of papers related to graphene are applied in LIB system, we demonstrate an interesting strategy that Shubin et al Yang synthesize a sandwich-like graphene-base titaniananosheets (seen scheme 2).Scheme 2 Illustration of sandwich compositeTo circumvent the drawbacks of titania, graphene with high electrical conductivity have beenutilized as matrices or conductive additives to improve its electrochemical performance. Thegraphene in the composite serve as a mini current collector, which can improve electronconductivity and leads to an dramatic improvement of electrochemical performance. As shown inthe Figure 4, it is striking that a high first discharge capacity of 269 mAh/g is achieved at a currentrate of 0.2 C (Figure 4), corresponding to a lithium insertion coefficient of 0.8 in Li0.8TiO2 . Thisvalue is much higher than the theoretical capacity of titania (167.5 mAh/g ) with the maximumcoefficient of 0.5 (Li0.5TiO2), suggesting the existence of additional lithium storage sites in ourG-TiO2 nanosheets.Figure 4 The cyclability of sandwich composite&TiO2ConclusionCarbon-base material, which can not only be served as an anode but also be used as an inactive material, plays an important role in lithium ion battery system. It arises from graphite, but it’s better than graphite for its breaking down the theoretical limitation of capacity( 372mAh/g ).This is particularly appropriate for the field of electrochemical energy storage, in which ‘graphene fever’ has reached rather high levels due to the continuous need for new materials that can meet the market’s performance requirements. We believe that Carbon-base material, especially graphene, will dominate the market of anode for a long time.Reference[1] Dengyu Pan et.a l. Li Storage Properties of Disordered Graphene Nanosheets. Chem. Mater. 2009, 21, 3136–3142[2] Zhong-Shuai Wu et.a l. Doped Graphene Sheets As Anode Materials with Superhigh Rate and Large Capacity for Lithium Ion Batteries. ACS Nano. 2011, Vol 5,No 7, 5463–5471[3]Shubin Yang et.al. Sandwich-Like, Graphene-Based Titania Nanosheets with High Surface Area for Fast Lithium Storage. Adv. Mate r. 2011, 23, 3575–3579[4] Arava Leela Mohana Reddy et.al. Synthesis Of Nitrogen-Doped Graphene Films For Lithium Battery Application. ACS Nano. 2010, Vol 4,No 11, 6337–6342[5] EunJoo Yoo et al. Large Reversible Li Storage of Graphene Nanosheet Families for Use in Rechargeable Lithium Ion Batteries. ACS2008 Vol.8 NO.8 2277-2282。
石墨烯的研究进展及应用的翻译讲稿
THE RISE OF GRAPHENE 今天我们汇报的主题为石墨烯。
主要从以下两个方面介绍，第一石墨烯的概况，第二石墨烯的各方面的应用。
I'm a science fiction fan, so let's take a look at a picture of a marvel superhero ,spider man,before I begin today's report. AND think about how far away from the spider man with our current technology..OK,Today our report is about graphene. We will introduce it in the following two aspects. The first is the brief introduction of graphene. The second is all applications of it.Graphene is a rapidly rising star on the horizon of materials science and condensed matter physics. Thisstrictly two-dimdensional material exhibits exceptionally high crystal and electronic quality and, despite itsshort history, has already revealed potential applications, which arebriefly discussed here.由于这些独特的特点，石墨烯有望用于多个领域。
石墨烯在电池方面的应用。
石墨烯作为一种超薄、透光性良好且电性能优异的导体材料, 成为金属氧化物电极比较好的替代材料。
石墨烯外国文献翻译
石墨烯基础材料的光电特性Inhwa Jung在这研究报告中，石墨烯基础材料的光电性能被调查，特别是研究具有氧化石墨单层的石墨烯氧化物的物理和化学性质和它的化学简式与石墨的不同。
尽管氧化石墨在一百多年前就被Brodie（在1859年）合成，但直到现在特殊层还没被深入研究，与我们正在研究的石墨烯氧化物比较，物理学家在原始石墨烯(石墨的一个层)发现了卓越的物理输送特性同时也显示石墨烯在纳米电子方面的潜力;这提高我们对包括石墨烯氧化物在内的化学法改变石墨性质的兴趣。
从石墨烯的光学性质方面来看，为了识别和测量石墨烯基底的有效光学性质，由于由硅上的薄介电层组成的基底的作用，一个直截了当的方法被提出。
通过这个方法和优化介电层的厚度，获得石墨烯基底独特晶片和基底的的巨大差别。
选择合适的光学性能和介电层的厚度，氧化石墨的有效折射率和光学吸收系数可以减少氧化石墨，通过对比预测与实际测量的差别可以获得石墨烯。
椭圆光度法成像是一种为光学成像和表征超薄材料（1nm~）例如特殊化学法改变的石墨烯晶片和少层氧化石墨烯晶片保持电势的方法，单独使用椭圆光度法成像无论能否确定它的光学性质和厚度都是非常有趣的，传统的光谱椭圆光度法也可以应用到比特殊晶片宽数毫米的多层叠加的氧化石墨上。
利用两种成像方法得到的结果对比最大的区别在于光学性质的差异。
观察热处理过的单体和多层叠加，多层叠加和单层的区别类似氧化石墨（无论是特殊晶片还是多层叠加）的对比结果。
分别从轮廓仪和AFM得到厚度，解释厚度和光学性质在热处理时会改变的模型被提出。
电学特征是前面提及的异常原始石墨性能基本的技术领域，通过在真空中加热单层石墨氧化物(沉积于基体)对材料的电阻率进行了监测。
通过监测随时间和温度响应的电导率能够表明,导电率的变化可能与一个激活的化学过程有关, 并由此可以获得活化能(势垒高度)。
通过高达85 S/m的时间温度曝光可以知道单层的氧化石墨的导电率，其次在真空中加热并与气相肼发生化学还原可以成倍地得到更高的导电率，如原始石墨一样，氧化石墨导电率对电场方向很敏感，伏安测量还表明，氧化石墨的电气性能与石墨烯存在差别。
详细 介绍石墨烯英文版
Notes Best electrical conductor of any known metal
59.6 × 106
Commonly used in electrical wire applications due to very good conductivity and price compared to silver.
Introduction
Properties of graphene
Mechanical properties
- High Young’s modulus (~1,100 Gpa) High fracture strength (125 Gpa)
- Graphene is as the strongest material
Content
Introduction to graphene. Preparation and characterization graphene Potential application of graphene Conclusions
Introduction to graphene
Graphene is a one-atom-thick planar sheet of sp2-bonded carbon atoms that are densely packed in a honeycomb crystal lattice The name ‘graphene’ comes from graphite + -ene = graphene
Molecular structure of graphene
High resolution transmission electron microscope images (TEM) of graphene
石墨烯
What is graphene?什么是石墨烯？Graphene is made of a single layer of carbon atoms that are bonded together in a repeating pattern of hexagons. Graphene is one million times thinner than paper; so thin that it is actually considered two dimensional.石墨烯是由碳原子构成的单层粘结在一起的六边形的重复图案的。
石墨烯是比纸薄一百万次;如此之薄，它实际上是考虑二维的。
Carbon is an incredibly versatile element. Depending on how atoms are arranged, it can produce hard diamonds or soft graphite. Graphene’s flat honeycomb pattern grants it many unusual characteristics, including the status of strongest material in the world. Columbia University mechanical engineering professor James Hone once said it is ―so strong it would take an elephant, balanced on a pencil, to break through a sheet of graphene the thickness of Saran Wrap,‖ according to the university.碳是一种令人难以置信的通用元素。
取决于如何原子的排列，它可以产生硬钻石或软石墨。
电池革命 美国nanotek公司新发明石墨烯电池-英文原文
/NanoLett Graphene Surface-Enabled Lithium Ion-Exchanging Cells:Next-Generation High-Power Energy Storage DevicesBor Z.Jang,*,†Chenguang Liu,†David Neff,†Zhenning Yu,‡Ming C.Wang,‡Wei Xiong,‡andAruna Zhamu*,†,‡†Nanotek Instruments,Inc.and‡Angstron Materials,Inc.,1242McCook Avenue,Dayton,Ohio45404,United Statesb Supporting InformationL ithium ion batteries and electrochemical capacitors(super-capacitors),separately or in combination,are being consid-ered for electric vehicle(EV),renewable energy storage,and smart grid applications.1À5A major scientific challenge is to either significantly increase the energy density of conventional supercapacitors or dramatically improve the power density of lithium ion batteries.2,3Supercapacitors work on two main charge storage mechan-isms:surface ion adsorption(electric double layer capacitance, EDL)and redox reactions(pseudocapacitance).1,2Compared with batteries,supercapacitors deliver a higher power density, offer a much higher cycle-life,need a very simple charging circuit, and are generally much safer.However,supercapacitors exhibit very low energy densities(e.g.,5Wh/kg cell for commercial activated carbon-based supercapacitors versus100À150Wh/ kg cell for the commercial Li-ion battery,all based on the total cell weight).2Previous attempts to increase the gravimetric energy of supercapacitors have included the use of electrode materials with enhanced gravimetric capacitances6or the pseudocapacitance provided by nanostructured transition metal oxides.7À9How-ever,the prohibitively high cost of ruthenium-based oxides and the cycling instability of manganese-based oxides9À11have impeded the commercial application of these supercapacitors. In2006,our research group reported graphene-based electrodes for both EDL and redox supercapacitors,12which has since become a topic of intensive research.13À19Significant progress has been made using pseudocapacitance(e.g.,redox pairs between graphene oxideÀMnO216or grapheneÀpolyaniline17,18)and ionic liquid electrolyte with a high operating voltage13,19for improved energy density.However,these supercapacitors have yet to exhibit a sufficiently high energy density or power density for EV and renewable energy applications.Lithium-ion batteries operate on Faradaic reactions in the bulk of the active material.This bulk storage mechanism provides a much higher energy density(120À150Wh/kg cell)as compared to supercapacitors.However,storing lithium in the bulk of a material implies that lithium must leave the interior of a cathode active particle and eventually enter the bulk of an anode active particle during recharge,and vice versa during discharge.Because of the extremely low solid-state diffusion rates,these processes are kinetics-limited.As a result,lithium ion batteries deliver a very low power density(100À1000W/kg cell),requiring typically hours for recharge.Several efforts have been made to increase the power char-acteristics of lithium-ion batteries by reducing the dimensions of lithium storage materials down to the nanometer scale,which would reduce the lithium diffusion time.20À23However,nanos-tructured lithium storage electrodes(e.g.,nanoparticles of lithium titanate anode or lithium iron phosphate cathode)are still not capable of delivering a power density comparable to that of supercapacitor electrodes.Recently,Lee et al.24used chemically functionalized multi-walled carbon nanotubes(MW-CNTs)to replace activated carbon(AC)as a cathode active material and Li4Ti5O12as an anode active material in a lithium-ion capacitor(LIC)cell.In this LIC cell,the Li4Ti5O12anode still requires lithium intercalationReceived:May31,2011Revised:August1,2011ABSTRACT:Herein reported is a fundamentally new strategy for the design of high-power and high energy-density devices.This approach is based on the exchange of lithium ions between the surfaces(not the bulk)of two nanos-tructured electrodes,completely obviating the need for lithium intercalation or deintercalation.In both electrodes,massive graphene surfaces in direct contact with liquid electrolyte are capable of rapidly and reversibly capturing lithium ions through surface adsorption and/or surface redox reaction.These devices,based on unoptimized materials and configuration,are already capable of storing an energy density of160Wh/kg cell,which is30times higher than that(5Wh/kg cell) of conventional symmetric supercapacitors and comparable to that of Li-ion batteries.They are also capable of delivering a power density of100kW/kg cell, which is10times higher than that(10kW/kg cell)of supercapacitors and100times higher than that(1kW/kg cell)of Li-ion batteries. KEYWORDS:Supercapacitor,battery,graphene,energy density,functional groupPublished:August08,2011into and out of the bulk of a solid particle,which remains slow and provides relatively low energy density and power density.Lee et al.24also investigated a half-cell con figuration,wherein the anode contains a current collector and a lithium foil.Very impressive power densities,even higher than those of super-capacitors,were observed.However,these exceptional power densities could only be achieved with an electrode thickness of 0.3À3μm obtained by the layer-by-layer (LBL)approach.Further,since the speci fic surface area of a current collector (typically ,1m 2/g)is too low to accommodate massive amounts of returning lithium ions,the overall lithium redeposi-tion rate can become surface area-limited.This con figuration is also conducive to the formation of dendrites upon repeated charges and discharges.A new paradigm is herein presented for constructing high-power lithium cells,which are totally graphene surface-mediated or surface-enabled,involving exchange of massive lithium ions between two nanostructured graphene electrodes.As illustrated in Figure 1,both the cathode and the anode are porous,having large amounts of graphene surfaces in direct contact with liquid electrolyte,thereby enabling fast and direct surface adsorption of lithium ions and/or surface functional group-lithium interaction,and obviating the need for intercala-tion.When the cell is made,particles or foil of lithium metal are implemented at the anode (upper portion of Figure 1a),which are ionized during the first discharge cycle,supplying a large amount of lithium ions.These ions migrate to the nanostruc-tured cathode through liquid electrolyte,entering the pores and reaching the surfaces in the interior of the cathode without having to undergo solid-state intercalation (lower left diagram in Figure 1a).When the cell is recharged,a massive flux of lithium ions are quickly released from the large amount of cathode surface,migrating into the anode zone.The large surface area of the nanostructured anode enable concurrent and high-rate deposition of lithium ions (lower right portion of Figure 1a),re-establishing an electrochemical potential di fference between the lithium-decorated anode and the cathode.A particularly useful nanostructured electrode material is the nanographene platelet (NGP),which refers to either a single-layer graphene sheet or multilayer graphene platelets.A single-layer graphene sheet is a 2D hexagon lattice of carbon atoms covalently bonded along two plane directions.25À28In this study,both oxidized and reduced single-layer and multilayer graphene were prepared from natural graphite (N),petroleum pitch-derived arti ficial graphite (M),micrometer-scaled graphite fibers (C),exfoliated graphite (G or EG),AC,carbon black (CB),and chemically treated carbon black (t-CB).AC and CB contain narrower graphene sheets or aromatic rings as a building block,while graphite and graphite fibers contain wider graphene sheets.Their microstructures all must be ex-foliated (to increase intergraphene spacing in graphite)or activated (to open up nano gates or pores,Figure 1b)to allow liquid electrolyte to access more graphene edges and surfaces (experimental details provided in Supporting Information).Coin-size cells were constructed to test these nanostructured carbon materials.Electrodes were prepared with 85%active material,5%conductive additive,and 10%binder.Results were calculated per total cathode material and per total cell weight (approximated as cathode weight Â5).The samples were thermally exfoliated graphite (Cell G),graphene from chemically reduced graphene oxide (Cell N),graphene from oxidized arti ficial mesophasegraphite (Cell M),graphene from oxidizedFigure 1.(a)Upper portion shows the structure of a fully surface-enabled,Li ion-exchanging cell when it is made,containing an anode current collector and a nanostructured material at the anode,a Li ion source (e.g.,pieces of Li foil or surface-stabilized Li powder),a porous separator,liquid electrolyte,a nanostructured functional material at the cathode.The lower left portion shows the structure of this cell after its first discharge (Li is ionized with the Li ions di ffusing through liquid electrolyte to reach surface-borne functional groups in the nanostruc-tured cathode and rapidly reacting with these groups).Lower right portion shows the structure of this cell after being recharged (Li ions are rapidly released from the massive cathode surface,di ffusing through liquid electrolyte to reach the anode side,where the huge surface areas can serve as a supporting substrate onto which massive amounts of Li ions can electrodeposit concurrently,and (b)schematic of the internal structure of a treated carbon black particle with pores or gates opened to provide accessibility by liquid electrolyte in such a manner that the functional groups attached to an edge or surface of an aromatic ring or small graphene sheet can readily react with Li ions.carbon fiber (Cell C),carbon black (Cell CB),oxidized carbon black (t-CB),and activated carbon (Cell AC).These materials have certain functional groups (e.g.,>C d O and ÀCOOH)that are naturally formed during the preparation process.The gra-phen oxide sheets are mostly single-layered,based on the results of combined Brunauer ÀEmmett ÀTeller (BET)surface analysis,atomic force microscopy (AFM)(Figure 2a),and transmission electron microscopy (TEM)(Figure 2b).The constituent graphite flakes in a graphite worm or exfoliated graphite (Figure 2c)remain interconnected as a network of 3D elec-tron-conducting paths,and the meso-and macroscaled pores between flake walls are easily accessible to liquid electrolyte.The Galvanostatic charge/discharge curves and cyclic voltam-metry (CV)diagrams of Cells M,C,G,and N are shown in Figure 3a,b,respectively.No clear redox peak is observed in Figure 3b.It may be noted that the CV curves of both the conventional pseudocapacitors and lithium-ion batteries tend to exhibit a strong redox peak due to slower Faradaic redox reactions in the bulk of an electrode active material (e.g.,polyaniline in a pseudocapacitor,lithium titanate in a lithium-ion battery,and Li x C 6O 6in an organic electrode battery 29).The lack of a strong,well-de fined redox reaction peak in the CVs of our fully surface-mediated devices and the LBL CNT device of Lee,et al.24might be due to the following reasons:(1)the reaction between surface functional groups and ultrasmall lithium ions are relatively fast and of low activation barrier (Figure 1b);24,25,30À32(2)fast adsorption of Li on a benzene ring center of a graphene sheet;33À35(3)fast trapping of Li ions in graphene defect sites;36and/or (4)electric double-layer formation.Possible lithium-capturing mechanisms of graphene surfaces are further discussed in Supporting Information.The NGP-mediated electrodes provide the cells (e.g.,Cell M)with a speci fic capacity of 127mAh/g at a current density of 1A/g,reaching an energy density of 85Wh/kg cell (Figure 3c)at a current density of 0.1A/g,which is 17times higher than the typically 5Wh/kg cell of commercial AC-based symmetric super-capacitors.The cell-level energy density and power density data presented in Figure 3c,d were obtained by dividing the corre-sponding values (based on single-electrode weight)in Support-ing Information Figure S12and S13bya factor of 5.Figure 2.(a)AFM image of single-layer graphene oxide sheets from natural graphite,(b)single-layer graphene sheets stacked over the sample-supporting TEM microgrids,and (c)scanning electron microscopy image of exfoliated graphite.Another graphene surface-mediated cell (Cell N,Figure 3d)exhibits an even higher energy density of 160Wh/kg cell ,comparable to that of a lithium-ion battery.The energy density of Cell-N maintains a value over 51.2Wh/kg cell even at a current density as high as 10A/g,delivering a power density of 4.55kW/kg cell .The power density of commercial AC-based symmetric supercapacitors is typically in the range of 1À10kW/kg cell at an energy density of 5Wh/kg cell ,This implies that,compared with a conventional supercapacitor at the same power density,the surface-mediated devices can deliver >10times the energy density.The power density of Cell N is 25.6kW/kg cell at 50A/g with an energy density of 24Wh/kg cell .The power density increases to 93.7kW/kg cell at 200A/g with an energy density of 12Wh/kg cell (Figure 3d).This power density is 1order of magnitude higher than that of conventional supercapacitors that are noted for their high power densities,and 2À3orders of magnitude higher than that (typically 0.1À1.0kW/kg cell )of conventional lithium-ion batteries.These data have clearly demonstrated that the surface-enabled cells are a class of energy storage cells by itself,distinct from both conventional supercapacitors and lithium-ion batteries.Figure 3b contains a comparison of CV data showing that the carbon fiber-derived graphene (Cell C)and mesophase carbon-derived graphene (M)have better performance than thermally exfoliated graphite (G)as an electrode active material.This is in line with the observation that C and M exhibited signi ficantly higher ÀCOOH and ÀC d O contents (Figure 4b),which are capable of capturing Li ions via a fast surface redox reaction.Figure 3d indicates that the energy density and power density values of CB can be signi ficantly increased by subjecting CB to a treatment that involves an exposure to a mixture of sulfuric acid,sodium nitrate,and potassium permanganate for 24h.The BET surface area was found to increase from approximately 122m 2/g to approximately 300m 2/g,resulting in a capacity increase from 8.47to 46.63mAh/g).Although AC has a high speci fic surface area (1200m 2/g),a signi ficant proportion of the pores in AC are microscopic pores (<1nm)and,hence,are not accessible to organic liquid electrolyte.Hence,Cell AC does not exhibit higher power and energy densities compared to NGP cells.The cycling performance for M cell is shown in Figure 4a and that for other cells (e.g.,N and AC)is in Supporting Information Figure S3.Measurements were taken once every 100cycles during a 0.1A/g charge and discharge,following the same method with literature 24(for comparison purpose).All other cycles were run at an accelerated rate of 1A/g.After 1000cycles,the retention of capacity remains above 95%,which illustrates the good cyclability of the electrode.The cyclability can be further improved with additional research.It may be noted that more than 30graphene surface-enabled cells have been investigated for more than 2000cycles,and we have found no evidence to indicate the initiation of any dendrite-like structure.The presence of functional groups,such as ÀCOOH and >C d O,in chemically prepared graphene oxide have been well documented.37,38The formation of these functional groups is a natural result of the oxidizing reactions of graphite by sulfuric acid and strong oxidizing agents (e.g.,nitric acid and potassium permanganate).Both unseparated graphite worms and the separated NGPs have surface-or edge-borne functional groups.Carbonyl groups (>C d O)in organic and polymeric electrodes were found to be capable of readily reacting with lithium ions to form redox pairs.24,29According to Lee et al.,24ÀCOOH groups on CNT surfaces are capable of reversibly and rapidly forming a redox pair with a lithium ion duringthe charge and dischargeFigure 3.(a)Charge/discharge curves of three surface-enabled cells (M =NGP from mesophase carbon-derived graphite,C =NGP from carbon fibers,G =from exfoliated natural graphite),and N =chemically reduced version of graphene oxide nanosheets.The discharge current density is 1A/g.(b)The CV plots of the same cells at the scan rate 25mV/s,(c,d)Ragone plots of these and CB,t-CB,and AC cells with thick cathodes.cycles of a battery.It is conceivable that Li ions also can react with the >C d O and ÀCOOH groups on the graphene planes or edges of separated graphene sheets,the unseparated graphene sheets that constitute graphite worms,and the aromatic rings (small graphene sheets)in AC or treated CB.The typical gravimetric capacitance of NGP electrodes in the voltage range 3À4.2V versus Li (with a comparable voltage scale of 0to ∼1.2V versus standard hydrogen electrode (SHE))is 150À350F/g.Since carbonyl (>C d O)groups,for instance,can be reduced by Li +and reversibly oxidized,capacitance obtained can be attributed to the Faradaic reactions of oxygen on the graphene edge or surface,illustrated as follows >C d O graphene þLi þþe ÀT >C ÀOLi grapheneOn the basis of elemental analysis,the oxygen content of natural graphite-,arti ficial graphite-,and carbon fiber-derived graphene oxide samples were 12.9,28.8,and 20.8%,respectively.The FTIR spectra of the three cathode materials,shown in Figure 4b,indicate that both Cell M and Cell C exhibit more ÀCOOH and >C d O groups compared to Cell G.This is consistent with the observations that Cells M and C exhibit higher energy density and power density than Cell G provided that Li bonding with these functional groups is a primary lithium-capturing mechanism.The role of surface functional groups in providing high capacitances in graphite-derived graphene was further illustrated by comparing the speci fic capacitance of the graphene material before and after exposure to a reduction treatment (in 4%H 2and 96%N 2at 900°C for 3h).As shown in Figure 4c,the gravimetric current of the graphene electrode in Cell M decreased consider-ably (by 65%)after this thermal reduction treatment to reduce the number of functional groups.The capacitance of the reduced-NGP cell is 43mAh/g and 50F/g at acurrent density of 1A/g.Figure 4.(a)Cycle performance of the graphene-enabled Cell M.Measurements were taken once every 100cycles during a 0.1A/g charge and discharge.All other cycles were run at an accelerated rate of 1A/g.By the end of the test,the capacity was 95%of the original value.The retention may be further improved with optimization of the material preparation procedure.(b)FTIR spectra of the three materials,indicating that both exfoliated mesophase carbon-and carbon-fiber-based electrodes (M and C)exhibit more ÀCOOH and >C d O groups compared to the exfoliated graphite sample (G).(c)Cyclic voltammetry plots of oxidized M cell and a partially reduced M cell.(d)Ragone plot of oxidized M cell and a partially reduced M cell,indicating signi ficantly reduced capacity,energy density,and power density when a signi ficant proportion of the functional groups was eliminated.(e)The Ragone plots of graphene surface-enabled Li ion-exchanging cells with di fferent electrode thicknesses.A comparison of the energy density and power density data in the Ragone plot of Figure4d seems to suggest that the reduction in oxygen content(hence,the functional group content)led to a reduction in lithium storage capability.This observation seems to be consistent with the proposed lithium storage mechanism via the surface-based redox reaction between Li and functional groups.However,more research is needed before a more definitive mechanism can be validated.The source of extra Li+ions(e.g.,Li powder)implemented at the anode and the Li+ions pre-existing in liquid electrolyte provide large amounts of Li+ions that can be shuttled between two nanostructured electrodes,which are fully capable of captur-ing these ions due to their massive surfaces areas.This is the main reason why the surface-enabled cells exhibit exceptional energy densities.If these ions can migrate at a sufficiently high rate(short migration times),then the ultrahigh power density would be expected.This is briefly discussed below:For describing the ion transport in a cell,the NernstÀPlanck(NP)equation(eq S4in Supporting Information)may be more accurate as compared to the Fick’s Law alone.This NP equation provides theflux of ions under the influence of both an ionic concentration gradient and an electricfield.The Supporting Information provides several significant observations:(1)Conventional lithium ion batteries featuring a micro-meter-sized graphite anode and a micrometer-sized LiFe-PO4would require several hours(e.g.,7.29h)tocomplete the required processes of intercalation in oneelectrode and deintercalation in the other electrode(Supporting Information Figure S5a).This problem ofa long diffusion time can be partially alleviated by usingnanoscaled particles.(2)For the fully surface-mediated cells,the electrode thick-ness is a dominating factor.For instance,in the case ofusing functionalized NGP as the electrodes(SupportingInformation Figure S8a),the total migration time of Liions in liquid electrolyte is1.27s if the cathode and anodeare each200μm thick and separator is100μm thick.Themigration time is reduced to0.318s if the anode=cathode thickness=100μm and separator thickness=50μm.The experimental charge and discharge time datashown in Supporting Information Figure S9a,b are con-sistent with the calculation results.For a cell with ananode center-to-cathode center distance of250μm,anion migration time of0.88s was obtained throughcalculations.Experimentally,under high current densityconditions the total discharge time was found to bebetween0.4and1.5s.(3)The above observations imply that the surface-enabledcells should have an extraordinary power density,parti-cularly when the electrodes are ultrathin.The powerdensities observed with graphene-enabled,fully surface-mediated cells(with an electrode thickness of80μm,Figure4e)are comparable or slightly superior to those ofLBL f-CNT-based batteries23(thickness of3μm)atcomparable current densities.There are great amounts of suitable sites available on the edges of a graphene sheet(in an NGP,AC,or CB nanostructure)or a graphiteflake(in an exfoliated graphite worm)to accept func-tional groups.The much lower cost of AC,CB,graphene,and exfoliated graphite,and their ease of forming a bulk electrode make these nanocarbons ideal electrode materials for this new class of high-power energy storage cell.In summary,a new generation of energy storage devices has been developed with the lithium storage mechanism and kinetics elucidated.These fully surface-enabled,lithium ion-exchanging cells with their materials and structures yet to be optimized are already capable of storing an energy density of160Wh/kg cell, which is30times higher than that of conventional electric double layer(EDL)supercapacitors.The power density of 100kW/kg cell is10times higher than that(10kW/kg cell)of conventional EDL supercapacitors and100times higher than that(1kW/kg cell)of conventional lithium-ion batteries. Figure4e nicely demonstrates that the surface-enabled cells are a class of energy storage cells by itself,distinct from both super-capacitors and lithium-ion batteries.More work is needed to more clearly differentiate the dominant lithium-storage mechanism(s)between surface redox,surface adsorption, and surface defect trapping.’ASSOCIATED CONTENTb Supporting Information.Description of materials and methods.This material is available free of charge via the Internet at .’AUTHOR INFORMATIONCorresponding Author*E-mail:(B.Z.J.)Bor.Jang@;(A.Z.) Aruna.Zhamu@.’ACKNOWLEDGMENTThe support from a U.S.NIST Technology Innovation Program(TIP)Grant(Program Managers:Mr.Carlos Grinspon and Dr.Felix Wu)is gratefully acknowledged.’REFERENCES(1)Conway,B.E.Electrochemical Supercapacitors:Scientific Funda-mentals and Technological Applications;Plenum Publishers:New York, 1999.(2)Simon,P.;Gogotsi,Y.Nat.Mater.2008,7,845–854.(3)Miller,J.R.;Simon,P.Science2008,321,651–652.(4)Kim,D.K.;Muralidharan,P.;Lee,H.;Ruffo,R.;Yang,Y.;Chan,C.K.;Peng,H.;Huggins,R.A.;Cui,Y.Nano Lett.2008,8,3948–3952.(5)Hu,L.B.;Choi,J.W.;Yang,Y.;Jeong,S.;Mantia,L.F.;Cui,L.F.; Cui,Y.PANS2009,106,21490–21494.(6)Chmiola,J.;Yushin,G.;Gogotsi,Y.;Portet,C.;Simon,P.; Taberna,P.L.Science2006,313,1760–1763.(7)Hu,C.C.;Chen,W.C.;Chang,K.H.J.Electrochem.Soc.2004, 151,A281–A290.(8)Fischer,A.E.;Pettigrew,K.A.;Rolison,D.R.;Stroud,R.M.; Long,J.W.Nano Lett.2007,7,281–286.(9)Amatucci,G.G.;Badway,F.;Du Pasquier,A.;Zheng,T. J.Electrochem.Soc.2001,148,A930–A939.(10)Reddy,A.L.M.;Shaijumon,M.M.;Gowda,S.R.;Ajayan,P.M. Nano Lett.2009,9,1002–1006.(11)B e langer,D.;Brousse,T.;Long,J.W.Electrochem.Soc.Interf. 2008,17,49–52.(12)Song,L.L.;Aruna,Z.;Guo,J.S.;Jang,B.Z.U.S.Patent Application11/499,861,August7,2006and U.S.Patent7,623,340, November24,2009.(13)Vivekchand,S.R.;Chandra,S.R.;Subrahmanyam,K.S.; Govindaraj,A.;Rao,C.N.J.Chem.Sci.2008,120,9–13.(14)Stoller,M.D.;Park,S.;Zhu,Y.;An,J.H.;Ruoff,R.S.Nano Lett. 2008,8,3498–3502.(15)Xia,J.;Chen,F.;Li,J.;Tao,N.Nat.Nanotechnol.2009, 4,505–509.(16)Chen,S.;Zhu,J.;Wu,X.;Han,Q.;Wang,X.ACS Nano2010, 4,2822–2830.(17)Yan,J.;Wei,T.;Shao,B.;Fan,Z.J.;Qian,W.Z.;Zhang,M.L.; Wei,F.Carbon2010,48,487–493.(18)Zhang,K.;Zhang,L.L.;Zhao,X.S.;Wu,J.S.Chem.Mater. 2010,22,1392–1401.(19)Liu,C.G.;Yu,Z.N.;Neff,D.;Aruna,Z.;Jang,B.Z.Nano Lett. 2010,10,4863–4868.(20)Kang,B.;Ceder,G.Nature2009,458,190–193.(21)Arico,A.S.;Bruce,P.;Scrosati,B.;Tarascon,J.;Schalkwijk,W. Nat.Mater.2005,4,366–377.(22)Poizot,P.;Laruelle,S.;Grugeon,S.;Dupont,L.;Tarascon,J. Nature2000,407,496–499.(23)Chan,C.K.;Peng,H.;Liu,G.;McIlwrath,K.;Zhang,X.F.; Huggins,R.;Cui,Y.Nat.Nanotechnol.2008,3,31–35.(24)Lee,S.W.;Yabuuchi,N.;Gallant,B.M.;Chen,S.;Kim,B.S.; Hammond,P.T.;Yang,S.H.Nat.Nanotechnol.2010,5,531–537. (25)Jang,B.Z.;Huang,W.C.U.S.Patent Application10/274,473, October21,2002and U.S.Patent7,071,258,July4,2006.(26)Novoselov,K.S.;Geim,A.K.;Morozov,S.V.;Jiang,D.;Zhang, Y.;Dubonos,S.V.;Grigorieva,I.V.;Firsov,A.A.Science2004, 306,666–669.(27)Jang,B.Z.;Aruna,Z.J.Mater.Sci.2008,43,5092–5101.(28)Park,S.;Ruoff,R.Nat.Nanotechnol.2009,4,217–224.(29)Le Gall,T.L.;Reiman,K.H.;Grossel,M.C.;Owen,J.R.J. Power Sources2003,119,316–320.(30)Chen,H.;Armand,M.;Demailly,G.;Dolhem,F.;Poizot,P.; Tarascon,J.M.ChemSusChem2008,1,348–355.(31)Han,X.Y.;Chang,C.X.;Yuan,L.J.;Sun,T.L.;Sun,J.T.Adv. Mater.2007,19,1616–1621.(32)Xiang,J.F.;Chang,C.X.;Li,M.;Wu,S.M.;Yuan,L.J.;Sun, J.T.Cryst.Growth Des.2008,8,280–282.(33)Sato,K.;Noguchi,M.;Demachi,A.;Oki,N.;Endo,M.Science 1994,264,556–558.(34)Dahn,J.R.;Zheng,T.;Liu,Y.H.;Xue,J.S.Science1995, 270,590–593.(35)Yoo,E.;Kim,J.;Hosono,E.;Zhou,H.;Kudo,T.;Honma,I. Nano Lett.2008,8,2277–2282.(36)Pan,D.;Wang,S.;Zhao,B.;Wu,M.;Zhang,H.;Wang,Y.;Jiao, Z.Chem.Mater.2009,21,3136–3142.(37)McAllister,M.J.;Li,J.;Adamson,D.H.;Schniepp,H.C.; Abdala,A.A.;Liu,J.;Herrera-Alonso,M.;Milius,D.L.;Car,R.; Prudhomme,R.K.;Aksay,I.A.Chem.Mater.2007,19,4396–4404.(38)Gilje,S.;Han,S.;Wang,M.;Wang,K.L.;Kaner,R.B.Nano Lett.2007,7,3494–3398.。
石墨烯
Selectivity in the Interaction of Electron Donor and Acceptor Molecules with Graphene and Single-Walled Carbon NanotubesNeenu Varghese,†Anupama Ghosh,†,‡Rakesh Voggu,†Sandeep Ghosh,†,‡and C.N.R.Rao*,†,‡Chemistry and Physics of Materials Unit,New Chemistry Unit and CSIR Centre of Excellence in Chemistry,Jawaharlal Nehru Centre for Ad V anced Scientific Research,Jakkur P.O.,Bangalore 560064,India,and Solid State and Structural Chemistry Unit,Indian Institute of Science,Bangalore 560012,India Recei V ed:August 5,2009;Re V ised Manuscript Recei V ed:August 29,2009Interaction of electron donor and acceptor molecules with graphene samples prepared by different methods as well as with single-walled carbon nanotubes (SWNTs)has been investigated by isothermal titration calorimetry (ITC).The ITC interaction energies of the graphene samples and SWNTs with electron acceptor molecules are higher than those with electron donor molecules.Thus,tetracyanoethylene (TCNE)shows the highest interaction energy with both graphene and SWNTs.The interaction energy with acceptor molecules varies with the electron affinity as well as with the charge-transfer transition energy for different aromatics.Metallic SWNTs interact reversibly with electron acceptor molecules,resulting in the opening of a gap.IntroductionRecent investigations of the interaction of electron donor and acceptor molecules with single-walled carbon nanotubes (SWNTs)have shown that molecular charge transfer affects the electronic structure of the nanotubes.1-4Thus,by the interaction of tetracyanoethylene (TCNE)and tetrathiafulvalene (TTF),it has been possible to introduce metallic to semiconducting transition and vice versa,but specificity of interaction with respect to the electronic nature of the SWNTs is not established.Interaction of electron donor and acceptor molecules with few-layer graphene has been investigated using Raman spectroscopy and other techniques.Molecular charge-transfer interaction between these molecules and graphene causes marked changes in the electronic structure of graphene.5First-principles calculations based on the DFT-GGA method suggest the interaction of graphene with donor and acceptor molecules to involve charge transfer,giving rise to the associated Raman band shifts.6We felt that it was important to carry out a comparative investigation of the interaction of donor and acceptor molecules with graphene and SWNTs in terms of the relative interaction energies.For this purpose,we have employed isothermal titration calorimetry (ITC)to measure the heats of interaction of a few electron donor and acceptor molecules with graphene and SWNTs.ITC is known to be a sensitive tool to study such binding interactions,as illustrated in the case of nucleobases.7,8ITC may not provide actual interaction energies but gives trends in interaction energies.Since SWNTs prepared by arc discharge and other methods constitute mixtures of semiconducting and metallic species,9we have investigated the interaction of pure metallic nanotubes,specially prepared by a new method,with donor and acceptor molecules,in order to examine the specificity of interaction.Besides showing that electron-withdrawing mol-ecules interact more strongly with graphene and SWNTs,the present study demonstrates that doping by charge transfer changes the Fermi level of SWNTs,to create a band gap in the initially metallic SWNTs.In the case of graphene also,a band gap is opened through charge transfer by electron acceptor molecules.Experimental SectionIsothermal titration calorimetric experiments were carried out with graphene samples prepared by three different methods,namely,thermal exfoliation of graphitic oxide (EG),10arc discharge of graphite in hydrogen (HG),11and conversion of nanodiamond (DG).12Dodecylamide derivatives of EG (EG-A)and DG (DG-A)were prepared by the literature procedure.13The graphene samples were characterized by atomic force microscopy (AFM),transmission electron microscopy (TEM),field-emission scanning electron microscopy (FESEM),and Raman spectroscopy.The EG,DG,and HG samples contained 3-4,5-6,and 2-3layers,respectively.The surface area of the HG sample is small (∼400m 2g -1)compared to DG (∼800m 2g -1)and EG (∼1100m 2g -1).EG-A ,DG-A,and HG dispersed in toluene were used in the experiments.ITC experiments were carried out with 1mg mL -1dispersions of graphene.The graphene dispersion was taken in the sample cell of the isothermal titration calorimeter and the reference cell filled with toluene.10mM solutions of tetracyanoethylene (TCNE),tetracyanoquinodimethane (TCNQ),2,4,7-trinitrofluo-renone (TNF),tetrathiafulvalene (TTF),and N ,N -dimethyl para-phenylenediamine (DMPD)were prepared in toluene.In each experiment,10µL of 10mM of each of these solutions taken in a syringe was added in equal intervals of 3min to the sample cell and the heat changes were measured after each addition.The experiments were carried out at a constant temperature of 26°C.Control experiments were performed by titrating the respective molecules against toluene under the same conditions,and the data so obtained were subtracted from the experimental data to eliminate the dilution effect.*To whom correspondence should be addressed.E-mail:cnrrao@jncasr.ac.in.Fax:+918022082760.†Jawaharlal Nehru Centre for Advanced Scientific Research.‡Indian Institute of Science.1685510.1021/jp9075355CCC:$40.752009American Chemical SocietyPublished on Web09/08/20092009,113,16855–16859SWNT samples were prepared by the arc discharge method and purified by successive acid and hydrogen treatment.14,15Metallic SWNTs were prepared by DC arc evaporation of a graphite rod containing the Ni +Y 2O 3catalyst,under a continuous flow of helium bubbled through Fe(CO)5.16The samples so obtained were nearly pure metallic SWNTs (around 95%).SWNT samples dispersed in o -dichlorobenzene (DCB)were sonicated for 1h to obtain 1mg mL -1solutions.Interaction of SWNTs with donor and acceptor molecules was studied in DCB solvent in the same manner as the graphene samples.In order to compare the results obtained with graphene and SWNTs,graphene samples (EG,EG-A,and HG)were also dispersed in DCB by sonication for 1h to obtain 1mg mL -1solutions.These solutions were used to study the interaction with TCNE.Results and DiscussionWe shall first discuss the results of ITC measurements on the interaction of graphenes with donor and acceptor molecules.Figure 1shows typical data obtained with 1.0mg mL -1solutions of EG-A in toluene with TCNE and TTF.Raw ITC data for the blank titration of 10mM TCNE and TTF against toluene are shown in Figure 1a and d.Figure 1b and e show the raw data for the titration of 10mM TCNE and TTF solutions against 1.0mg mL -1EG-A solution.The ITC response in the TCNE and TTF titrations against EG-A is exothermic,as shown in Figure 1b and e.In order to eliminate dilution effects,heats from the blank titration data were subtracted from the molecule -graphene titration data.Figure 1c and f show the integrated heat changes (enthalpy changes in kcal mol -1)aftereach injection of TCNE and TTF,respectively,after correcting for the heat of dilution.The exothermicity of the peaks reduces with progressive injection as the number of free sites for the binding of molecules available on the graphene decreases.The heat of reaction curve should ideally be sigmoidal in shape,but the limited solubility of graphene in toluene does not permit recording of the initial part of the sigmoidal curve.Absolute binding energies cannot therefore be obtained from the present data.The relative affinities of the different electron donor and acceptor molecules can,however,be estimated from the heat liberated in the initial injections,since all of the experiments were performed under similar conditions.The relative binding energies obtained from the initial points of the integrated heat plots in the case of EG-A and HG are listed in Table 1.The trend in the relative binding energies of electron acceptor molecules with EG-A obtained from ITC measurements isFigure 1.ITC data recorded for the interaction of TCNE and TTF with EG-A.ITC response for the blank titration with TCNE (a)and TTF (d).The raw ITC data for the titration of TCNE and TTF with 1.0mg mL -1of EG-A is shown in parts b and e.Parts c and f show the integrated heat of reaction at each injection of TCNE and TTF,respectively.TABLE 1:Energies of Interaction of Graphene and SWNTs with Electron Donor and Acceptor Molecules Obtained from ITC Measurements (in kcal mol -1)aEG-A bHG b SWNT c TCNE -5.88d -4.2-4.25TCNQ -0.24-0.32TNF -0.12-0.30-0.06DMPD -0.40-0.12-7.4e TTF-0.07-0.18aThe concentration of graphene and SWNTs was 1mg mL -1in all of the cases.b In toluene solvent.c In o -dichlorobenzene (DCB)solvent.d With DG-A,the value is -1.6.e This high value is due to interaction with the semiconducting SWNTs.16856J.Phys.Chem.C,Vol.113,No.39,2009LettersTCNE >TCNQ >TNF.Interaction energies of electron donor molecules with the graphene samples are considerably lower,the highest value being with N ,N -dimethyl para-phenylenedi-amine (DMPD).The interaction energy of TTF is lower than that of DMPD.In the case of the interaction of TCNE with the different graphene samples,the highest ITC interaction energy is found to be with EG-A (-5.9kcal mol -1)and the lowest with DG-A (-1.6kcal mol -1).It is noteworthy that the surface area of EG is highest among the graphene samples.17Interaction energies of graphene with different donor and acceptor molecules have been calculated by employing first-principles calculations using a linear combination of atomic orbital DFT methods implemented in the SIESTA package.6This study shows evidence for charge transfer between graphene and the donor and acceptor molecules.According to this study,the interaction energies of graphene with TCNE and TCNQ are greater than that with TTF.This is consistent with the results from our ITC studies.The calculations also show that a gap develops in the electronic structure of graphene on interaction with these molecules.We have obtained ITC interaction energies of SWNTs with donor and acceptor molecules by a procedure similar to that with graphene by using o -dichlorobenzene (DCB)as the solvent.Typical data obtained for 1.0mg mL -1solutions of SWNTs in DCB interacting with TCNE and TTF are given in Figure 2,the raw data for the blank titration of 10mM TCNE and TTF against DCB being shown in Figure 2a and d,respectively.Raw data for the titration of 10mM TCNE and TTF solutions against the 1.0mg mL -1SWNT solution are given in Figure 2b and e.The ITC response in the titrations is exothermic,as revealed by Figure 2b and e.The integrated heat changes after each injection of TCNE and TTF,respectively (after correcting for the heat of dilution),are shown in Figure 2c and f.Just as in the case of graphene,exothermicity of the peaks reduces with progressive injection.The energies of interaction calculated from the initial points of the integrated heat plots are listed in Table 1.It is interesting that,for electron acceptor molecules,the trend in the ITC interaction energies with SWNTs is the same as that with graphene (TCNE >TCNQ >TNF).Among the donor molecules,DMPD shows a higher interaction energy than TTF.Since the data for SWNTs were obtained in DCB solvent,we wanted to compare the data of graphenes in the same solvent.The relative interaction energies of TCNE in DCB solvent are -1.4,-0.7,and -0.6kcal mol -1with EG-A,EG,and HG,respectively,giving the trend EG-A >EG >HG.This trend parallels that of the surface area.The interaction energy of SWNTs (-4.3kcal mol -1)with TCNE is generally larger than that for the graphene samples.First-principles calculations of Pati in this laboratory (personal communication)has shown the interaction energy of SWNTs with TCNQ to be greater than that with TTF.SWNTs exhibit a higher interaction energy than graphene.Interaction energies of graphene as well as SWNTs with electron acceptor molecules increase progressively with the electron affinities of the acceptors,as can be seen in Figure 3a.18This result confirms that charge transfer between the acceptor molecules and graphene or SWNTs contributes sig-nificantly to the interaction energy.Indirect confirmation of this conclusion is also provided by the fact that the interaction energy varies systematically with the charge-transfer transition energy,Figure 2.ITC data recorded for the interaction of TCNE and TTF with SWNTs.ITC response for the blank titration with TCNE (a)and TTF (d).The raw ITC data for the titration of TCNE and TTF with 1.0mg mL -1of SWNT is shown in parts b and e.Parts c and f show the integrated heat of reaction at each injection for TCNE and TTF,respectively.Letters J.Phys.Chem.C,Vol.113,No.39,200916857hυCT,of the acceptors with an aromatic such as anthracene,19-21 as shown in Figure3b.SWNTs prepared by arc-discharge and other methods contain a mixture of metallic and semiconducting species,9the propor-tion of semiconducting nanotubes being around66%.The interaction energies that we have given in Table1correspond to the mixture of metallic and semiconducting SWNTs.It would be more instructive if one were able to determine the interaction energy between the donor and acceptor molecules with pure metallic or semiconducting nanotubes.ITC measurements on the interaction of metallic SWNTs with donor and acceptor molecules reveal the interaction energy to be high in the case of TCNE(-7.4kcal mol-1),the energy varying in the order TCNE>TNF>TCNQ in the case of the acceptor molecules (Table2).Interaction energies of acceptor molecules with metallic SWNTs are generally higher than those with the as-prepared SWNTs(containing the mixture of metallic and semiconducting species).The interaction energy of metallic nanotubes with a donor molecule such as TTF is negligible and could not be measured by ITC.This result shows that metallic nanotubes specifically interact with electron-withdrawing mol-ecules.In order to understand the nature of this interaction,we examined the effect of acceptor and donor molecules on the Raman spectrum of metallic SWNTs.In Figure4,we show the Raman G-band of metallic nanotubes before and after the interaction with TCNE(10mM).On interaction with TCNE, the feature around1540cm-1due to the metallic species1,22disappears completely and the band maximum shifts to1582 cm-1.This change in the Raman spectrum corresponds to the opening of a gap due to a change in the Fermi level of SWNTs, giving rise to an apparent metal-semiconductor transition. Electron-donating molecules have no effect on the Raman spectrum of metallic SWNTs.First-principles calculations also show that metallic(9,0)SWNTs develop a gap on interaction with TCNE.Electron-donating molecules,however,specifically interact with semiconducting nanotubes.Raman spectra show that semiconducting SWNTs exhibit an intense metallic feature in the1540cm-1region on interaction with TTF. ConclusionsIn conclusion,ITC provides a satisfactory means to investi-gate the interaction of graphene as well as SWNTs with electron donor and acceptor molecules.Although ITC does not provide absolute interaction energies,it gives trends in interaction energy which are of value.Interaction energies of electron acceptor molecules(TCNE,TCNQ,and TNF)with graphene samples are higher than those of electron donor molecules(TTF and DMPD).Among the different graphene samples,the function-alized graphene EG-A shows the highest interaction energy.The studies carried out by us are on few-layer graphenes,but it would be somewhat difficult to investigate single-layer graphenes in this manner owing to its agglomeration in solid state.Interaction energies of SWNTs obtained from ITC are generally higher than those with graphene samples.Here again,TCNE gives the highest interaction energy.Metallic SWNTs interact reversibly with electron acceptor molecules,such as TCNE,the interaction energy being higher than with as-prepared SWNTs(containing a mixture of metallic and semiconducting species).On interac-tion of metallic SWNTs with TCNE,the metallic feature in the Raman G-band disappears,due to the opening of a gap through molecular charge transfer.It would be worthwhile to study the interaction of pure semiconducting SWNTs with donor and acceptor molecules by a combined use of ITC Raman spectroscopy.Figure3.Variation of interaction energies of EG-A and SWNTs with electron acceptors(a)with the electron affinity of acceptors,E A,and (b)with the charge-transfer transition energy,hυCT,with anthracene (EG-A,squares;SWNTs,circles;metallic SWNTs,triangles).TABLE2:Energies of Interaction of SWNTs with Electron Donor and Acceptor Molecules Obtained from ITC Measurements(in kcal mol-1)aSWNT b metallic SWNT TCNE-4.25-7.4TCNQ-0.32-0.64TNF-0.06-0.80TTF-0.18+0.07a The concentration of SWNTs was1mg mL-1in DCB solvent in all of the cases.b Mixture containing66%semiconducting and 33%metallic SWNTs.Figure4.Raman G-band of(a)metallic SWNTs and(b)metallic SWNTs after interaction with TCNE(10mM).16858J.Phys.Chem.C,Vol.113,No.39,2009LettersAcknowledgment.We thank indaraj for help with the preparation of SWNTs.References and Notes(1)Voggu,R.;Rout,C.S.;Franklin,A.D.;Fisher,T.S.;Rao,C.N.R. J.Phys.Chem.C2008,112,13053–13056.(2)Shin,H.J.;Kim,S.M.;Yoon,S.M.;Benayad,A.;Kim,K.K.; Kim,S.J.;Park,H.K.;Choi,J.Y.;Lee,Y.H.J.Am.Chem.Soc.2008, 130,2062–2066.(3)Tournus,F.;Latil,S.;Heggie,M.I.;Charlier,J.C.Phys.Re V.B 2005,72,075431(1-5).(4)Strano,M.S.;Dyke,C.A.;Usrey,M.L.;Barone,P.W.;Allen, M.J.;Shan,H.;Kittrell,C.;Hauge,R.H.;Tour,J.M.;Smalley,R.E. Science2003,301,1519–1522.(5)Das,B.;Voggu,R.;Rout,C.S.;Rao,mun. 2008,5155–5157.Voggu,R.;Das,B.;Rout,C.S.;Rao,C.N.R.J.Phys.: Condens.Matter2008,20,472204(1-5).(6)Manna,A.K.;Pati,S.K.Chem.s Asian J.2009,4,855–860.(7)Ladbury,J.E.;Chowdhry,B.Z.Chem.Biol.1996,3,791–801.(8)Das,A.;Sood,A.K.;Maiti,P.K.;Das,M.;Varadarajan,R.;Rao,C.N.R.Chem.Phys.Lett.2008,453,266–273.Varghese,N.;Mogera, U.;Govindaraj,A.;Das,A.;Maiti,P.K.;Sood,A.K.;Rao,C.N.R. ChemPhysChem2008,10,206–210.(9)Rao,C.N.R.;Govindaraj,A.Nanotubes and Nanowires;RSC Nanoscience&Nanotechnology series;Royal Society of Chemistry: Cambridge,U.K.,2005.(10)Schniepp,H.C.;Li,J.L.;McAllister,M.J.;Sai,H.;Herrera-Alonso,M.;Adamson,D.H.;Prud’homme,R.K.;Car,R.;Saville,D.A.; Aksay,I.A.J.Phys.Chem.B2006,110,8535–8539.(11)Subrahmanyam,K.S.;Panchakarla,L.S.;Govindaraj,A.;Rao,C.N.R.J.Phys.Chem.C2009,113,4257–4259.(12)Andersson,O.E.;Prasad,B.L.V.;Sato,H.;Enoki,T.;Hishiyama, Y.;Kaburagi,Y.;Yoshikawa,M.;Bandow,S.Phys.Re V.B1998,58, 16387–16395.(13)Subrahmanyam,K.S.;Vivekchand,S.R.C.;Govindaraj,A.;Rao,C.N.R.J.Mater.Chem.2008,18,1517–1523.Rao,C.N.R.;Biswas,K.; Subrahmanyam,K.S.;Govindaraj,A.J.Mater.Chem.2009,19,2457–2469.(14)Journet,C.;Maser,W.K.;Bernier,P.;Loiseau,A.;Lamy de la Chapelle,M.;Lefrant,S.;Deniard,P.;Lee,R.;Fischer,J.E.Nature1997, 388,756–758.(15)Vivekchand,S.R.C.;Govindaraj,A.;Sheikh,M.M.;Rao,C.N.R. J.Phys.Chem.B2004,108,6935–6937.(16)Voggu,R.;Govindaraj,A.;Rao,C.N.R.Condens.Matter2009, arXiv:0903.5359v1.Voggu,R.;Ghosh,S.;Govindaraj,A.;Rao,C.N.R. J.Nanosci.Nanotechnol,in press.(17)Subrahmanyam,K.S.;Voggu,R.;Govindaraj,A.;Rao,C.N.R. Chem.Phys.Lett.2009,472,96–98.(18)Briegleb,G.Angew.Chem.,Int.Ed.1964,3,617–632.(19)Dewar,M.J.S.;Rogers,H.J.Am.Chem.Soc.1962,84,395–398.(20)Acker,D.S.;Hertler,W.R.J.Am.Chem.Soc.1962,84,3370–3374.(21)Lepley,A.R.J.Am.Chem.Soc.1962,84,3577–3588.(22)Das,A.;Sood,A.K.;Govindaraj,A.;Saitta,A.M.;Lazzeri,M.; Mauri,F.;Rao,C.N.R.Phys.Re V.Lett.2007,99,136803(1-4).JP9075355Letters J.Phys.Chem.C,Vol.113,No.39,200916859。
英文文献翻译
英⽂⽂献翻译天然⽯墨烯作为锂离⼦电池负极材料的先进表⾯和显微结构特点为了改进天然⽯墨作为锂离⼦电池负极材料在长时间循环中不可逆容量损失和容量滞留，天然⽯墨要经受⼀系列的热处理。
在惰性氮⽓和氩⽓中进⾏基线热处理被⽐作添加炉内⽓体，这种添加实际上改变了未包覆⽯墨粉的化学表⾯，导致显著提⾼锂离⼦电池长时间的循环性能在商业上、碳包覆⽯墨⽅⾯。
在950~2900摄⽒度不同的热处理温度表明会满⾜不同要求在长时间循环过程中，并且减少热预算。
⼀个详细的特征数据被呈现包括X射线衍射、X射线光电⼦能谱、拉曼光谱、温度升温吸附质谱。
在锂离⼦的全电池中特性数据和可以观察到是容量衰减提⾼⼤电流放电的长时间循环。
有⼈认为长期性能提⾼是形成更稳定的固体电解质界⾯膜在负极⽯墨表⾯所形成的，这些是和表⾯化学修饰直接相关的，被专有⽓体环境在热处理过程中。
2.钒酸锂/⽯墨复合材料作为锂离⼦电池负极材料的电化学性能研究研究表明，⽤⽯墨烯精梳Li3VO4和⽤碳包覆Li3VO4能有效提⾼它的电化学性能，Li3VO4/C复合材料作为锂离⼦电池负极材料具有很⼤的电势。
然⽽，从⾼成本、复杂的合成⽅法、聚合的难易程度等⽅⾯来考虑，⽯墨烯相⽐于其他碳材料有很多缺点，因此不适合⼤规模⽣产。
与⽯墨烯相反，天然⽯墨在⾃然界中很丰富，相⽐于其他碳材料有很⼤优势，⽐如：低成本、电⼦导电率⾼并且结构稳定性好，这些特点使得天然⽯墨成为⼀种优良的复合电极材料。
在这篇⽂章中，我们⽤⼀种温和的⽅法将Li3VO4纳⽶粒⼦沉积在天然⽯墨上，⽤这种⽅法合成的⽯墨作为锂离⼦电池负极材料具有优良的电化学性能。
设备简单、成本低、预备反应效率⾼等特点有利于⼤规模合成Li3VO4/天然复合材料及在锂离⼦电池中的实际应⽤。
实验：制作⼯序分析级化学试剂（上海化学试剂⼚）天然⽯墨（宜昌恒⼤⽯墨公司99.9%）在⼀个典型程序中1 mmol V2O5, 3 mmol Li2CO3 and 5 mmol 环六亚甲基四胺（乌洛托品）溶解于30ml蒸馏⽔中。
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
石墨烯基础材料的光电特性Inhwa Jung在这研究报告中，石墨烯基础材料的光电性能被调查，特别是研究具有氧化石墨单层的石墨烯氧化物的物理和化学性质和它的化学简式与石墨的不同。
尽管氧化石墨在一百多年前就被Brodie（在1859年）合成，但直到现在特殊层还没被深入研究，与我们正在研究的石墨烯氧化物比较，物理学家在原始石墨烯(石墨的一个层)发现了卓越的物理输送特性同时也显示石墨烯在纳米电子方面的潜力;这提高我们对包括石墨烯氧化物在内的化学法改变石墨性质的兴趣。
从石墨烯的光学性质方面来看，为了识别和测量石墨烯基底的有效光学性质，由于由硅上的薄介电层组成的基底的作用，一个直截了当的方法被提出。
通过这个方法和优化介电层的厚度，获得石墨烯基底独特晶片和基底的的巨大差别。
选择合适的光学性能和介电层的厚度，氧化石墨的有效折射率和光学吸收系数可以减少氧化石墨，通过对比预测与实际测量的差别可以获得石墨烯。
椭圆光度法成像是一种为光学成像和表征超薄材料（1nm~）例如特殊化学法改变的石墨烯晶片和少层氧化石墨烯晶片保持电势的方法，单独使用椭圆光度法成像无论能否确定它的光学性质和厚度都是非常有趣的，传统的光谱椭圆光度法也可以应用到比特殊晶片宽数毫米的多层叠加的氧化石墨上。
利用两种成像方法得到的结果对比最大的区别在于光学性质的差异。
观察热处理过的单体和多层叠加，多层叠加和单层的区别类似氧化石墨（无论是特殊晶片还是多层叠加）的对比结果。
分别从轮廓仪和AFM得到厚度，解释厚度和光学性质在热处理时会改变的模型被提出。
电学特征是前面提及的异常原始石墨性能基本的技术领域，通过在真空中加热单层石墨氧化物(沉积于基体)对材料的电阻率进行了监测。
通过监测随时间和温度响应的电导率能够表明,导电率的变化可能与一个激活的化学过程有关, 并由此可以获得活化能(势垒高度)。
通过高达85 S/m的时间温度曝光可以知道单层的氧化石墨的导电率，其次在真空中加热并与气相肼发生化学还原可以成倍地得到更高的导电率，如原始石墨一样，氧化石墨导电率对电场方向很敏感，伏安测量还表明，氧化石墨的电气性能与石墨烯存在差别。
在特殊气体中对石墨氧化物进行初步的灵敏度的测量，结果表明石墨氧化物可以作为传感器的材料，于是用以测量灵敏度和特殊气体浓度的方案被提出和讨论，该方法建立在光学检测上，因此这篇论文会涉及光学特性在实际生活中的潜在应用。
摘要--------------------------------------------------------------3 感谢--------------------------------------------------------------6 目录--------------------------------------------------------------81.介绍-----------------------------------------------------------182.理论及文献探讨2.1石墨的结构和其电气性能----------------------------------------21 2.2石墨烯作为传感材料的应用--------------------------------------24 2.3石墨烯的光学可视化和表征--------------------------------------26 2.4几种获得石墨烯基底材料的技巧----------------------------------28 2.5石墨烯氧化物的结构和制备方法----------------------------------292.6石墨烯氧化物的独特性------------------------------------------313.石墨烯基底材料的光学特性3.1概述----------------------------------------------------------33 3.2高对比度成像和描述石墨烯基底的简单方法------------------------353.2.1介绍-------------------------------------------------------353.2.2实验-------------------------------------------------------383.2.3结果和讨论-------------------------------------------------433.2.4深入讨论和提供信息-----------------------------------------593.2.5总结-------------------------------------------------------72 3.3热处理减少石墨烯氧化物基底材料的椭偏仪特征--------------------733.3.1介绍------------------------------------------------------733.3.2实验------------------------------------------------------753.3.3结果和讨论------------------------------------------------833.3.4总结------------------------------------------------------984.单层石墨烯氧化物的电学特性4.1概述----------------------------------------------------------99 4.2石墨烯氧化物的电子输送测量-----------------------------------1014.2.1介绍-----------------------------------------------------1014.2.2热还原研究-----------------------------------------------1034.2.3比较化学还原和气体环境的影响-----------------------------1134.2.4实验和分析细节-------------------------------------------1194.2.5深入讨论和提供信息---------------------------------------1374.2.6总结-----------------------------------------------------1405.潜在应用及对未来工作的建议5.1在特殊气体中灵敏度的定量测量---------------------------------1415.2图案还原-----------------------------------------------------1426.总结-----------------------------------------------------------1447.参考文献------------------------------------------------------1451.介绍石墨是碳的一种同素异形体，它具有稳定的化学性质和良好的导电性。
由于储量丰富，通常被用作填料和导电材料。
众所周知，碳纳米管由单层石墨烯（单层石墨）组成（概念上）。
好像单壁碳纳米管,石墨烯(从平面内石墨的性能)被认为有优异的物理性能,使其成为填充材料、复合材料的潜在候选人。
据目前报道石墨烯有很强的双极性电气场效应，这使其用于电气设备和传感器潜在应用提供保证。
对石墨烯研究的越来越热。
在图1 –1，可以看出关于石墨烯已出版的论文数量今年超过10。
石墨不能剥离成大量单层石墨烯，这使之前的文献没有提及的。
到目前为止最成功获得单层或者多层薄层是通过摩擦膨胀石墨的机械表面或者通过带有胶带的高导向热解石墨搓到另一个硅晶片。
然而得到一层或者非常薄得多层叠合物的几率很低，通常叠合物的横向尺寸很小（少于几毫米的单层横向尺寸）。
为了通过实际设备制造基础石墨烯底层，需要大量单层底层和可再生制造方法。
为了实现大量相对大的侧面尺寸的剥离石墨，我们使用一个众所周知的化学过程实现石墨转换成石墨氧化物，然而这种转换会使原始石墨的特性发生改变，石墨氧化物是不导电的，氧化石墨如果不剥落可以通过溶液化学还原转化成石墨，一旦在水中进行氧化石墨的水相分散，单层底片可以减少。
在这个报告中，我们主要关注石墨烯氧化物和减少石墨烯氧化物薄片（我们指单层石墨氧化物为石墨烯氧化物）。
在这些研究中，为识别单层石墨烯氧化物薄片而发展了一个系统，基于这个系统和方法，单层石墨烯氧化物薄片的光学性质的测量和配置电子的测量可以做到，通过四探针测量器对石墨烯氧化物薄片进行电气测量可以显示导电材料的还原效果。
我们的最终目标是制作对特殊气体敏感的传感器。
2.理论及文献探讨2.1石墨的结构和其电气性能石墨完全由碳原子组成，图表2-1显示了三维碳堆积结构的例子。
如石墨架构图所示，每个碳原子通过共价键与其他三个碳原子形成一个完全的两空间层，每一层通过范德华力键合，因为范德华力作用力远远比共价键弱得多，所以石墨在每一层的每个方向上都可以裂开。
为了得到一个单层的石墨烯，很多人尝试剥离大块石墨。
据目前报道石墨可以通过简单的微机械分裂技术剥离成一层或者少数层。
这开辟了关于石墨烯的凝聚态物理学研究新领域。
有趣的是石墨烯这种材料展现电场效应，它说明石墨烯可以作为晶体管，图表2-2的场效应晶体管（FET）可以由石墨烯实现，根据石墨烯FET的电流结果可知，材料的导电率以独特栅极电压函数的方式改变。
石墨烯的栅极依赖关系总结在图表2-3，在图中可以看出，电阻率的变化取决于提供的栅极电压。
通过提供一个高的栅极电压电阻率被大大地减少（无论是积极的还是消极的）。
对比单壁的碳纳米管的栅极依赖关系，石墨烯栅极依赖关系是十分特殊的。
如2-4所示，通过增加栅极电压，单壁碳纳米管的导电率被减少，由于只含有空穴载流子，所以石墨烯被误认为P型半导体。
顺便说，石墨烯同时表现出P型和S型半导体的特征，这被理解为材料同时带有空穴和电子，这些可以被提供的栅极电压控制，当温度降低时，栅极电压的影响变得越来越明显。
图表2-5还总结了石墨烯的其他的方面性质，如图2-5（a）所示，薄片的厚度增加，栅极偏置效果消失，大块石墨只是简单导电而没有依赖于栅极。