Co-catalyst Modified Si-based Photoelectrode Materials for Solar Water Splitting

The current global energy consumption rate is approximately 15 TW per year. Developing a renewable energy resource as a substitute for fossil fuels and nuclear power is a research topic that needs attention. In 1972, Honda and Fujishima first demonstrated the conversion of solar energy into chemical fuels by splitting water. The only product of using hydrogen gas from water photoelectrolysis is environmental friendly water vapor. Therefore, solar water splitting is an optimal method for solving the energy crisis. Among numerous semiconductor materials, silicon (Si) is the optimal photocathode because of its small band gap and negative conduction band edge. Consequently, Si photocathode absorbs the visible light of solar spectrum and drives solar hydrogen evolution reaction. However, the low kinetics of photo-induced carriers in Si photocathode restricted its photoelectrochemical performance. Moreover, the formation of an insulating oxidation layer on Si photocathode during the exposure of aqueous electrolyte contributed to its photocatalytic degradation or deactivation. In the present study, three dominant strategies were developed to improve the performance and durability of Si photocathode. Surface plasmon resonance metal particles and co-catalyst material modification were applied to enhance the efficiency of the Si photocathode. A passivation layer served as a protective shell that is attached to the Si photocathode to increase its stability.