Abstracts Book - IMRC 2018

• SC3-O019 Invited Talk
CONTSTRUCTIONS OF PHOTOCATALYTIC AND
PHOTOELECTROCHEMICAL WATER SPLITTING SYSTEMS UNDER
VISIBLE LIGHT
Katayama Masao 1
1 The University of Tokyo, Department of Chemical System Engineering, Japan.
Photocatalytic and photoelectrochemical water splitting has attracted much
attention as a means of sustainable solar hydrogen production. We have studied
various semiconducting oxides, (oxy)nitrides, and (oxy)chalcogenides as
photocatalysts and photoelectrodes for water splitting under visible light. In this
talk, constructions of water splitting systems by using various photocatalysts are
presented. LaMg1/3Ta2/3O2N, a solid solution of LaMg2/3Ta1/3O3 and LaTaON2,
absorbs photons up to 600 nm and produces hydrogen and oxygen under
visible light irradiation when being modified with Rh2-yCryO3 as a hydrogen
evolution cocatalyst. However, nitrogen is also generated simultaneously
because of the self-oxidation of the oxynitride. It was found that amorphous
TiOx coating on LaMg1/3Ta2/3O2N suppressed the self-oxidation and enabled
LaMg1/3Ta2/3O2N modified with Rh2-yCryO3 to split water stoichiometry. 2-step
excitation system for water splitting reaction is also a promising approach
because photocatalysts with narrow bandgaps that are active either for water
reduction or oxidation are applicable. Recently we have developed
photocatalyst sheets consisting of SrTiO3:La,Rh and BiVO4 embedded onto
conductive layers. The conductive layers enable efficient charge transfer
between the two kinds of photocatalysts. By using gold as conductive layers, the
photocatalyst sheet showed significantly higher activity in the overall water
splitting reaction than a conventional powder suspension system of
SrTiO3:La,Rh and BiVO4.
Keywords: Photocatalyst, Photoelectrochemistry, Water splitting
Presenting authors email: katayama@chemsys.t.u-tokyo.ac.jp