2, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, , China
It is a promising way to resolve the worldwide energy crisis and environmental pollution by converting solar energy into storable chemical energy through solar water splitting or CO2 reduction. However, the conversion efficiency is still relatively low since complicated processes involved in photocatalysis, including charge generation, transportation and surface reaction. Given the fact that all these three processes could become the rate limiting step during solar-to-chemical energy conversion, different strategies have been taken to manipulate photogenerated excitons to enhance the photocatalytic efficiencies. Firstly, self-doping has been adopted to narrow the bandgap of TiO2 to generate more charge carriers upon visible light illumination, while avoiding the introduction of excessive bulk defects that serve as charge recombination centers. Secondly, nanotube and 3-D junction structures have been realized for Fe2O3 photoanodes, which significantly improves the charge transportation of this semiconductor with a very short hole diffusion length. Finally, the particle size and distribution of Co3O4 surface co-catalysts have been carefully controlled to construct an effective p-n junction that facilitates the charge separation at the semiconductor/co-catalyst interface, obtaining a synergetic enhancement of surface reaction kinetics and bulk charge separation. With all the effort to better manipulate photogenerated excitons in semiconductors, the era of highly effective photocatalytic conversion process for practical applications will be realized.