Metal Sulfide Photocatalysts for Hydrogen Generation by Water Splitting Under Illumination of Solar Light

Solar energy is a decentralized and inexhaustible natural resource with the magnitude of available power of 122,000 TW. Highly effective utilization of solar energy is arguably the most promising way to address the issues of energy shortage, climate change, and environmental pollution. Photocatalytic water splitting for hydrogen energy is a promising process for solar energy absorption, conversion, and storage. Visible-light-driven photocatalysts have extensively been developed aiming at solar hydrogen production from water. Metal sulfide photocatalysts represented by ZnS and CdS show high activities for sacrificial H2 evolution from aqueous solutions containing electron donors. Metal sulfides are attractive materials as candidates of visible-light-driven photocatalysts. The valence band usually consists of S 3p orbitals, the level of which is more negative than O 2p. Many metal sulfide photocatalysts have been reported for H2 evolution in the presence of sacrificial reagents. Such an achievement will contribute to global energy and environmental issues in the future resulting in bringing about an energy revolution.