Nanostructures Design: the Role of Cocatalysts for Hydrogen and Oxygen Generation in Photocatalytic Water Splitting

Due to the energy supply pressure caused by non-renewable fuels as well as the environment-related issues, the efficient conversion of solar-chemical energy via photo-induced water splitting is one of the promising strategies to address the existing problems. To strengthen the overall catalytic performance of photocatalytic hydrogen (H2) and oxygen (O2) evolution, the selection and construction of cocatalysts are crucial. Recently, the semiconductor photocatalysts have been well modified with the loaded cocatalysts as the active sites by extending the light harvest, promoting the electron separation and transfer, and improving the photocatalytic activity. Combined with the principles of photocatalysis, the paper focuses on the mechanism and roles of cocatalysts for boosted photocatalytic water splitting in recent research. The categories with the corresponding research contents of the existing cocatalysts are also summarised, including cocatalysts for H2 evolution, cocatalysts for O2 evolution, and dual cocatalysts for overall water splitting. Finally, the future direction of the development is suggested for the rational design and large-scale application of highly efficient cocatalysts in the photo-induced water splitting system.