Overall Water Splitting on Dye-modified Inorganic Semiconductor Photocatalysts

Photocatalytic water splitting is a potential next generation hydrogen production process which can directly convert light energy to chemical energy without greenhouse gas emission. The effects of dye-modification on the water splitting activity of inorganic semiconductor photocatalysts were investigated to utilize visible light energy for solar energy conversion. The photocatalytic activities of metal oxides, sulfides, oxysulfides, and oxynitrides were improved by dye-modification, because the charge recombination of photogenerated electrons and holes in inorganic semiconductors was effectively suppressed. The charge transfer mechanism of the dye-modified photo catalyst is a two-step excitation process, which is similar to that of photosynthesis. This study revealed that dye modification is a very effective method to enhance the photoabsorption of visible light and improve the water splitting activity of inorganic semiconductor photocatalysts.