光解水催化剂介绍photocatalysts

major developing history
special structures—perovskites Aurivillius phases Dion-Jacobson phases Ruddleson-Popper phases
major developing history
special structures—perovskites amazing effects of the network of octahedral units of metal cations
Photo-catalysts for water splitting
赵宇 黄子健 王宏宇 2016年11月23日
first discovery and basic principles
First discovered at 1972
initiated by the demonstration of photo-electrochemical (PEC)
Strategy to improve the photocatalytic activity
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Strategy to improve the photocatalytic activity
This high activity appears to be due to the thin walls of the mesopores, which provide a short distance for the excited electrons and holes to travel to the surface, reducing the probability of electron– hole recombination.
Improving the physicochemical properties of the photocatalyst
Refining cocatalysts
Controlling the reaction conditions
Strategy to improve the photocatalytic activity
major developing history
metal-free photocatalysts
electron transitions from the valence band populated by N2p orbitals to the conduction band formed by C2p orbitals
hybridized s,p orbitals have a large dispersion, leading to increase mobility of photogenerated electrons in the conduction band
major developing history
pentagonal prism tunnel
built-in polarization field
[26] Y. Inoue, T. Niiyama, Y. Asai, K. Sato, J. Chem. Soc., Chem. Commun. (1992
major developing history
major developing history
Water splitting through two-step photoexcitation (Z-scheme)
controlling the selectivity for the forward reactions on each photocatalyst
well-known as the Honda-Fujishima effect
first discovery and basic principles
energy band theory
different energy levels correspond with different bands
local internal fields due to the dipole moment inside the distorted units
major developing history
special electronic structures—d10-Type metal oxides Ga2 O3
major developing history
special structures—the well-known lamellar particle
major developing history
special structures—perovskites
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Cubic Perovskites
Double Perovskites
special electronic structures—d10-Type metal oxides MGa2 O4
the poor symmetry of octahedral and tetrahedral coordination tends to lead to the formation of isolated orbitals
1、the band gap restriction 2、migrate without recombination 3、inhibit the backward reaction
example: Pt-TiO2 at 1980 with NaOH loaded on the cocatalyst
K. Maeda / Journal of Photochemistry and Photobiology C: Photochemistry Reviews 12 (2
full-occupied half-occupied unoccupied band gap CB VB
first discovery and basic principles
semi-conductors are very useful in this area
K. Maeda / Journal of Photochemistry and Photobiology C: Photochemistry Reviews 12 (2
Strategy to improve the photocatalytic activity
the biggest problem is the back electron transfer
major developing history
development of visible light utilization—Spectralsensitization
slow electron transfer from the nanoparticulate IrO2 catalyst to the oxidized dye which does not compete effectively with back electron transfer from the conduction band of TiO2 to the dye
A Tradeoff
A small size
increases the density of surface catalytic sites
increase the probability of recombination between photogenerated electrons and holes,
major developing history
development of visible light utilization
provides a discreet energy level
totally new band
major developing history
development of visible light utilization-valence band control
major developing history
development of visible light utilization—Spectralsensitization
organic dyes or inorganic narrow-gap semiconductors
energy gap sufficiently small to harvest visible photons excited-state potential that is more negative
special electronic structures—mixed-configuration metal oxides
hybridization of the atomic orbitals of the two metal ions show effect on the density of states and energy dispersion in the conduction bands increase the mobility of photoexcited electrons and holes
first discovery and basic principles
test reactions for overall water splitting
first discovery and basic principles
generally to be particles
specific needs that must be met
[32] T.Takata,K.Shinohara,A.Tanaka,M.Hara,J.N.Kondo,K.Domen,J.Photochem. Photobiol. A: Chem. 10
major developing history
special structures—perovskites: tunnel structured BaTi4O9 and Na2Ti6O9
Shape or form of a photocatalyst
Mesoporous transition-metal oxides
Nomura and Domen et al., reported that a mesoporous tantalum oxide, prepared by a ligand-assisted templating method, functions as a photocatalyst capable of splitting water into H2 and O2 under UV irradiation (" > 200 nm), when modified with an NiOx cocatalyst.
major developing history
Water splitting through two-step photoexcitation (Z-scheme)
Strategy to improve the photocatalytic activity
Ways to improve photocatalytic activity
probably from its unique electronic properties
major developing history
special structures：Ruddlesden–Popper type layered perovskites of A2La2Ti3O10
a series of layered perovskites have AQYs higher than 20% under UV irradiation