Photoelectrochemical CO2 reduction with copper-based photocathodes

The excessive consumption of fossil fuels has led to a rapid surge in atmospheric CO2 concentration, triggering severe energy crises and environmental concerns. In this context, photoelectrochemical (PEC) technology for CO2 reduction is perceived as a highly appealing resolution, due to its integration of the advantages offered by both photocatalysis and electrocatalysis. Undoubtedly, the photocathode plays a pivotal role within the PEC CO2 reduction system. Among various catalysts, copper (Cu)-based photocathodes have garnered significant attention owing to their low toxicity, affordability, advantageous band gap and distinctive active sites that enable the conversion of CO2 into a diversity of reduction products including carbon monoxide (CO), formic acid (HCOOH), methane (CH4), ethylene (C2H4), ethanol (C2H5OH) and so on. This review primarily delves into the current developments of Cu-based photocathodes in PEC CO2 reduction, encompassing aspects like material fabrication processes and modification techniques. Subsequently, an analysis is presented regarding the reaction mechanisms underlying different CO2 conversion products. Finally, an anticipatory perspective is provided regarding future research in the field of PEC CO2 reduction. This review enables researchers to promptly capture the latest advancements of Cu-based photocathode for PEC CO2 reduction, offers valuable insights for future research on the design and synthesis of Cu-based photocathode, and provides a guideline to achieve enhanced improvements in PEC CO2 conversion.