Visible-Light-Induced H2 Evolution from an Aqueous Solution Containing Sulfide and Sulfite over a ZnS-CuInS2-AgInS2 Solid-Solution Photocatalyst

摘要

The photocatalytic splitting of water to generate H2 and O2 has attracted attention as a clean energy system. An important feature of this system is that it does not require complicated devices: the photocatalysts are simply placed in water, irradiated with sunlight, and then hydrogen is produced by a photocatalytic reaction. This water-splitting reaction does not depend on fossil fuels, and is therefore an ideal method to produce clean hydrogen fuel. The reaction is also attractive from the viewpoint of achieving an artificial photosynthesis, which converts light into chemical energy. Many active photocatalysts for splitting water under UV irradiation have been reported. In particular, the NiO-loaded NaTaO3:La photocatalyst showed extremely high activity, and the quantum yield amounted to 56 % at 270 nm.[1] However, photocatalysts with wide band gaps (3 eV or above) do not absorb visible light, which is a large part of the solar spectrum. It is indispensable to develop highly active photocatalysts with a visible-light response.