Developing silicon-based photocathodes for CO2 conversion

Photoelectrochemical (PEC) conversion of CO2 presents a promising avenue for solar-driven chemical fuel production, with silicon emerging as a cost-effective and high-light-absorbing material pivotal to this technology. Aiming at exploring opportunities for industrializing PEC CO2 reduction (PEC-CO2R) by minimizing reaction energy consumption, enhancing reaction efficiency and selectivity, this review summarizes recent advancements in developing Si-based photocathodes for PEC-CO2R. It outlines the fundamental principles, advantages, and limitations of Si photocathodes with key performance metrics. Based on this understanding, the strategies to enhance the performance of the PEC-CO2R system, including light absorption, charge separation, and catalytic reactions are categorized as the interfacial modification, active site decoration, and protective layer design. The design ideas of this advantageous three-layer structure in promoting the efficiency, stability, and selectivity have been clarified. Then, this review scrutinizes the influence of the photocathodic chemical environment. This review consolidates the mechanism insights and notable breakthroughs of various fuel generation processes within Si-based PEC-CO2R systems. Providing this wealth of information offers an up-to-date perspective on the dynamic developments in silicon-based PEC-CO2 conversion and underscores the promising pathways toward the sustainable fuel synthesis from pollutant CO2.