Replacing Cu2+ with Zn2+ in Cu2-xSe fuels electron delocalization for efficient photocatalytic CO2 reduction

Photocatalytically converting CO 2 into high-value-added chemicals represents an effective strategy for realizing energy conversion and environmental remediation. Herein, a Zn 2+ -doped Cu 2-x Se (Zn-Cu 2-x Se) photocatalyst was successfully synthesized via a self-sacrificial template method. Zn 2+ doping modulates the electronic structure of Cu 2-x Se, transforming its semiconductor properties from p-type to n-type, thereby enhancing the interfacial electron delocalization effect. The accelerated transfer of delocalized electrons from Zn to Cu and Se sites drives the multi-electron reduction reaction of CO 2 . In-situ DRIFTS and DFT calculations corroborate that electron-enriched Zn-Cu 2-x Se significantly lowers the reaction energy barriers for both CO 2 activation and the hydrogenation of *CO (the key intermediate). The optimized Zn-Cu 2-x Se photocatalyst achieved a CH 4 production yield of 8.63 nmol·cm -2 under visible-light irradiation, with a high CH 4 selectivity of 93.84%. This work underscores the significance of optimizing the local electronic structure of photocatalysts to achieve selective CO 2 conversion.