Promising Photocathodes Based on Non-noble Metal Catalysts of CoSe2 or CoS2 with Heterostructure of Si for Photoelectrochemical Hydrogen Evolution

摘要

In consideration with the upcoming energy crisis and current environmental issues, alternative and efficient green energy sources are urgently needed. In this respect, hydrogen is a very promising clean energy source, which can fulfill the energy demands. Photoelectrochemical (PEC) water splitting is a highly controlled approach to convert sunlight into clean and storable hydrogen and oxygen. A large scale effort has already been dedicated to find out this alternative and also to fulfill the dream by generating higher photocurrent density. However, the major problem in PEC system is that it is very hard for a single material to achieve all the requirements. Visible light-active materials suffer from photocorrosion, whereas wide-bandgap materials can be activated by UV light only. Higher photocurrents can be achieved by coupling two semiconductors with a type-II band alignment. Nevertheless, the problem of sluggish hydrogen and oxygen evolution reaction rate decreases the efficiency of a material. Another approach to solve this problem is to decorate the semiconductor surface with a suitable co-catalyst, which further lowers the overpotential by increasing the kinetics of photoexcited electrons.