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.