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

Abstract Solar‐driven CO 2 reduction suffers from severe hole accumulation and inefficient electron utilization due to the sluggish kinetics of H 2 O oxidation to O 2 , thereby impeding the multi‐electron C─C coupling process. This results in poor catalytic activity of C 2 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 H 2 O to H 2 O 2 , significantly accelerating hole consumption and thereby enhancing the electron reduction reaction of CO 2 at the metal center. Under illumination, the C 2 H 6 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 C 2 product synthesis. Research indicates that the enrichment of π electrons on the benzene ring of the catalyst can stabilize the H 2 O oxidation intermediate *OH, consuming a significant number of holes to form H 2 O 2 . 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 CO 2 to C 2 products. This work provides new insights into the economic viability of photocatalytic CO 2 reduction to C 2 H 6 under pure H 2 O conditions.