Nanoheterostructured photocatalysts for improving photocatalytic hydrogen production

Rapid industrialization has accordingly increased the demand for energy. This has resulted in the increasingly severe energy and environmental crises. Hydrogen production, based on the photocatalytic water splitting driven by sunlight, is able to directly convert solar energy into a usable or storable energy resource, which is considered to be an ideal alternative energy source to assist in solving the energy crisis and environmental pollution. Unfortunately, the hydrogen production efficiency of single phase photocatalysts is too low to meet the practical requirements. The construction of heterostructured photocatalyst systems, which are comprised of multiple components or multiple phases, is an efficient method to facilitate the separation of electron-hole pairs to minimize the energy-waste, provide more electrons, enhance their redox ability, and hence improve the photocatalytic activity. We summarize the recent progress in the rational design and fabrication of nanoheterostructured photocatalysts. The heterojunction photocatalytic hydrogen generation systems can be divided into type-I, type-II, pn-junction and Z-scheme junction, according to the differences in the transfer of the photogenerated electrons and holes. Finally, a summary and some of the challenges and prospects for the future development of heterojunction photocatalytic systems are discussed.