Production of High-Value-Added Chemicals on Oxide Semiconductor Photoanodes under Visible Light for Solar Chemical-Conversion Processes

This study reviews recent progress on the oxidative production of various high-value-added chemicals using simple and inexpensive oxide semiconductor photoanodes for technology associated with solar-to-chemical conversion processes. The photoelectrochemical production of oxidizing reagents can be highly economical and contribute to global warming by replacing the conventional processes. Various oxidizing reagents and useful chemicals, such as hydrogen peroxide (H2O2), hypochlorous acid (HClO), persulfates (H2S2O8), IO4–, Ce4+, and organic compounds, can be produced photoelectrochemically with excellent faradaic efficiencies. This process also allows H2O2 production via both photoanodic and cathodic reactions without external bias. These photoelectrochemical processes are key technologies enabling the expansion of solar energy utilization toward a sustainable and low-carbon society.