A Z‐Scheme CuWO 4 /Poly(heptazine imide) Interface Coupled With Asymmetric Cu 2+ /Cu + Sites Enables Efficient Photocatalytic CO 2 ‐to‐Ethanol Conversion

ABSTRACT Selective photocatalytic reduction of CO 2 into multicarbon products remains challenging because constructing uniform C─C coupling centers while maintaining their stability under reaction conditions is difficult. Here, we report a Z‐scheme CuWO 4 /poly(heptazine imide) heterojunction featuring asymmetric Cu 2+ /Cu + dual sites for CO 2 ‐to‐ethanol conversion. Site‐selective oxygen vacancies in CuWO 4 trigger generation of structurally identical, charge‐asymmetric neighboring Cu sites, which enhance CO 2 activation and stabilize adjacent *CO intermediates, thereby facilitating C─C bond formation. Meanwhile, an atomically bonded O─W─N heterointerface enables directional Z‐scheme charge transfer, supplying photogenerated electrons to the CuWO 4 surface and stabilizing the asymmetric Cu 2+ /Cu + dual sites throughout photocatalysis. Consequently, the optimized photocatalyst achieves an ethanol production rate of 244.5 µmol g −1 h −1 in pure water without sacrificial reagents. Advanced synchrotron spectroscopies identify the asymmetric Cu 2+ /Cu + dual sites and the chemically bonded heterointerface, while operando spectroscopies record the dynamic evolution of active sites and the * CO─ * CO coupling pathways upon illumination. Density functional theory calculations reveal that the synergy between asymmetric catalytic centers and the atomically bonded heterointerface promotes the C─C coupling process. This work establishes a strategy for constructing and stabilizing asymmetric catalytic centers through atomic engineering of crystal structure and heterointerface, providing a photocatalyst design paradigm for selective multicarbon solar fuel synthesis.