Unlocking Copper-Free Interfacial Asymmetric C–C Coupling for Ethylene Photosynthesis from CO2 and H2O

Solar-driven carbon dioxide (CO₂) reduction into C₂₊ products such as ethylene represents an enticing route toward achieving carbon neutrality. However, due to sluggish electron transfer and intricate C–C coupling, it remains challenging to achieve highly efficient and selective ethylene production from CO₂ and H₂O beyond capitalizing on Cu-based catalysts. Herein, we report a judicious design to attain asymmetric C–C coupling through interfacial defect-rendered tandem catalytic centers within a sulfur-vacancy-rich MoS_x/Fe₂O₃ photocatalyst sheet, enabling a robust CO₂ photoreduction to ethylene without the need for copper, noble metals, and sacrificial agents. Specifically, interfacial S vacancies induce adjacent under-coordinated S atoms to form Fe–S bonds as a rapid electron-transfer pathway for yielding a Z-scheme band alignment. Moreover, these S vacancies further modulate the strong coupling interaction to generate a nitrogenase-analogous Mo–Fe heteronuclear unit and induce the upward shift of the d-band center. This bioinspired interface structure effectively suppresses electrostatic repulsion between neighboring *CO and *COH intermediates via d-p hybridization, ultimately facilitating an asymmetric C–C coupling to achieve a remarkable solar-to-chemical efficiency of 0.565% with a superior selectivity of 84.9% for ethylene production. Further strengthened by MoS_x/WO₃, our design unveils a promising platform for optimizing interfacial electron transfer and offers a new option for C₂₊ synthesis from CO₂ and H₂O using copper-free and noble metal-free catalysts.