Embed Oxygen-Tolerant Active Site for Enhanced Photocatalytic CO 2 Reduction in Oxygenated Atmosphere

Photocatalytic conversion of CO2 in realistic oxygen-containing gas streams remains extremely challenging because O2 strongly competes for photogenerated electrons and initiates thermodynamically favored ORR, thereby suppressing CO2RR. Here, we report an oxygen-tolerant photocatalyst constructed by embedding Au atoms into Ni-based alloy nanoclusters supported on TiO2, followed by controlled etching to expose unsaturated Au sites while maintaining Ni–Au cooperative centers. The optimized E1.5-Ni5Au1–TiO2 catalyst exhibits substantially enhanced CO2RR performance under 5% O2, and it sustains CO formation with nearly 100% selectivity and a rate of 375.5 μmol g–1 h–1. The pronounced shift in product selectivity from CH4 to CO is directly linked to the evolution of these specific atomic sites and O2 accessible microenvironment. Time-resolved in situ DRIFTS and DFT calculations further demonstrate that Au incorporation significantly weakens O2 adsorption, reduces charge transfer to O2, and suppresses ORR, while expanded Au exposure amplifies this effect. These findings establish that engineering specific atomic coordination environments via etching to expose oxygen-tolerant active sites provides an effective strategy for enabling aerobic photocatalytic CO2 reduction, offering mechanistic insights and a pathway toward practical CO2 utilization in oxygenated industrial gas streams.