major developing history
metal-free photocatalysts
electron transitions from the valence band populated by N2p orbitals to the conduction band formed by C2p orbitals
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.
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
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
Water splitting through two-step photoexcitation (Z-scheme)
controlling the selectivity for the forward reactions on each photocatalyst
major developing history
special structures—the well-known lamellar particle
major developing history
special structures—perovskites
Cubic Perovskites
Double Perovskites
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
[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
major developing history
Water splitting through two-step photoexcitation (Z-scheme)
Strategy to improve the photocatalytic activity
Ways to improve photocatalytic activity
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)
A Tradeoff
A small size
increases the density of surface catalytic sites
increase the probability of recombination between photogenerated electrons and holes,
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
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
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
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
local internal fields due to the dipole moment inside the distorted units
major developing history
special electronic structures—d10-Type metal oxides Ga2 O3
full-occupied half-occupied unoccupied band gap CB VB
first discovery and basic principles
semi-ห้องสมุดไป่ตู้onductors are very useful in this area
K. Maeda / Journal of Photochemistry and Photobiology C: Photochemistry Reviews 12 (2
Improving the physicochemical properties of the photocatalyst
Refining cocatalysts
Controlling the reaction conditions
Strategy to improve the photocatalytic activity
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
well-known as the Honda-Fujishima effect
first discovery and basic principles
energy band theory
different energy levels correspond with different bands