Cu‐ZnS Modulated Multi‐Carbon Coupling Enables High Selectivity Photoreduction CO2 to CH3CH2COOH

Abstract

The direct photocatalytic conversion of CO2 and H2O into high‐value C3 chemicals holds great promise but remains challenging due to the intrinsic difficulty of C1–C1 and C2–C1 coupling processes and the lack of clarity regarding the underlying reaction mechanisms. Here, the design and synthesis of a Cu‐ZnS photocatalyst featuring dispersed Cu single atoms are reported. These Cu single atoms are coordinated with S atoms, forming unique Cu‐S‐Zn active units with tunable charge distributions that interact favorably with surface‐adsorbed intermediates. This configuration stabilizes the *COHCO intermediate and facilitates its subsequent coupling with *CO to form *COCOHCO both thermodynamically and kinetically favorable on the Cu‐ZnS surface. Notably, multiple critical C3 intermediates, including *COCOHCO, *OCCCO, and *CHCHCO, are identified, providing a clear reaction pathway for CO2 to CH3CH2COOH conversion. The Cu‐ZnS photocatalyst achieves a CO2 to CH3CH2COOH conversion rate of 0.45 µmol h−¹ with an electron selectivity of 91.2%. Remarkably, in the presence of triethanolamine, the production rate increases to 16.9 µmol h−¹ with a selectivity of 99.8%. These findings underscore the importance of modulating multicarbon coupling processes to enable the efficient photocatalytic transformation of CO2 into C3 products, paving the way for future advancements in sustainable chemical synthesis.