New Energy and Industrial Technology Development Organization, Artificial Photosynthesis Chemical Process Technology Research, said that it succeeded in developing a photocatalyst that decomposes water into hydrogen and oxygen with a quantum yield (photon utilization efficiency) close to 100%, which is the theoretical maximum. The joint research group of the union, Shinshu University, Yamaguchi University, the University of Tokyo, and the Industrial Technology Research Institute announced.
If water can be decomposed into hydrogen and oxygen using solar energy, hydrogen can be produced cleanly.For this purpose, it is necessary to develop a photocatalyst that improves the efficiency of solar energy conversion, but there have been few reports that the quantum yield of the photocatalysts developed so far reaches 50%.
In this study, SrTiO3 (Al-doped), which is one of the typical oxide photocatalysts, is used, and the particle shape is controlled by the flux method to expose a specific crystal plane, and then the specific crystal plane is exposed by the photoelectric adhesion method. A hydrogen production co-catalyst (Rh / Cr2O3) and an oxygen production co-catalyst (CoOOH) were separately supported on the crystal surface.In the conventional photocatalyst, recombination of electrons and holes was the cause of the decrease in quantum yield, but in this structure, the electrons and holes excited by the potential gradient in the semiconductor fine particles are respectively. Since it selectively moves to the co-catalyst, electrons and holes are spatially separated, and recombination is almost completely suppressed.As a result, water splitting with a quantum yield close to 100% was achieved for the first time in the world in the ultraviolet light region.
The most important element of light energy conversion is to move photoexcited electrons and holes in a certain direction, and it can be said that the photocatalyst developed in this study is a model of this.The SrTiO3 used this time has a large bandgap and can only use ultraviolet light, but by applying the catalyst design guideline found this time to a photocatalyst that has a smaller bandgap and absorbs light with wavelengths in the visible region, the solar energy conversion efficiency Can be expected to improve.
Paper information:[Nature] Photocatalytic water splitting with a quantum efficiency of almost unity
