Activity Breakthrough in CO 2 Photoreduction to C 2 H 6 via Accelerated Electron Accumulation from H 2 O Photooxidation to H 2 O 2

Solar-driven CO₂ reduction suffers from severe hole accumulation and inefficient electron utilization due to the sluggish kinetics of H₂O oxidation to O₂, thereby impeding the multi-electron C─C coupling process. This results in poor catalytic activity of C₂ products. Herein, we have constructed a conjugated stacked thiophene-based supramolecular catalyst with extensive π-electron delocalization by introducing a benzene ring. This effectively promotes the oxidation of H₂O to H₂O₂, significantly accelerating hole consumption and thereby enhancing the electron reduction reaction of CO₂ at the metal center. Under illumination, the C₂H₆ production rate reached 101.1 µmol·g^-1·h^-1 with an electron selectivity as high as 98%. Compared to existing advanced systems, this represents an order-of-magnitude breakthrough in activity for C₂ product synthesis. Research indicates that the enrichment of π electrons on the benzene ring of the catalyst can stabilize the H₂O oxidation intermediate *OH, consuming a significant number of holes to form H₂O₂. This process enhances the separation and migration of photo-generated electrons at the active center and promoting the *CO-bridged C─C coupling. This significantly increases the ability to reduce CO₂ to C₂ products. This work provides new insights into the economic viability of photocatalytic CO₂ reduction to C₂H₆ under pure H₂O conditions.