Strategies for improving photoelectrochemical water splitting performance of Si-based electrodes

Abstract

Si, as a narrow bandgap semiconductor with a broadband absorption for sunlight, is considered to be a very competitive photoelectrode material for solar-driven photoelectrochemical (PEC) water splitting. However, there are major barriers in construction of efficient and stable Si-based PEC cell, including low photovoltage, sluggish reaction kinetics, and poor stability in electrolytes. This review focuses on the strategies to solve these issues and summarizes recent progress. The working principles of PEC water splitting are first introduced. Then the strategies for improving Si-based photoelectrode performances are discussed, including (1) the regulation of Si surface morphology for enhancing light harvesting, (2) band structure engineering strategies to reduce recombination of photogenerated carriers, and (3) modification of protection layers for long stability and loading cocatalysts on Si-based photoelectrodes for accelerating water splitting. Lastly, we have presented some issues of Si-based photoelectrode materials, which should be addressed in future research.