Principle Design of C-C Coupling Pathway Towards Highly Selective C2 Products Using Photocatalytic CO2 Reduction:A Review.

Photocatalytic conversion of environmental CO2 into valuable fuels is expected to alleviate fossil fuel and pollution problems. However, intricate product-reaction pathways complicate the regulation of product selectivity. Most studies in this field have focused on increasing productivity rather than on controlling product formation. To date, the major products of photocatalytic CO2 reduction reactions (CO2RRs) are C1 compounds, as opposed to the higher-value C2 compounds, because of the low C2 selectivity of this process. The design of C-C coupled pathways is paramount to facilitate selective access to C2 products in the photocatalytic CO2RR. In this review, we discuss the mechanisms and pathways of CO2RR product generation based on recent research results and summarise the work on CO2RR to C2 products. This review aims to modulate the product-generation pathway to improve the yield and selectivity of C2 products by facilitating C-C coupling reactions. Finally, some of the current challenges in the field of the CO2RR to C2 are outlined, including possible mechanistic interpretations, cost of catalyst use, reactor design, and potential solutions.