In Situ Light‐Induced Bi‐O Vacancy Pair Activated Ag‐Bi Dual Site in Bi ₁₂ O ₁₇ Cl ₂ Nanotubes for Efficient CO ₂ ‐to‐CO Photoreduction

ABSTRACT Photocatalytic CO 2 reduction performance critically depends on surface electronic reconstruction under illumination, but receives less attention. Here, we unveil the in situ formed Bi─O vacancy pairs mediated Ag nanoparticles photodeposition and reconstructed reaction sites on 1D Bi 12 O 17 Cl 2 nanotubes. The transformation of 2D nanosheets to 1D nanotubes enables the exposure of more surface coordination unsaturated atoms for defect construction. Combined experimental and density functional theory calculations demonstrate that the resulting Bi─O vacancy pairs and Ag nanoparticles collaboratively promote charge accumulation on vacancy‐adjacent Bi atoms, and drive the reaction site evolution from an isolated Ag atom to cooperative Ag‐Bi dual sites. The dual sites not only promote the adsorption and activation of CO 2 molecules, but also significantly lower the Gibbs free‐energy barrier for the rate‐limiting * COOH intermediate formation. Benefiting from these advantages, the optimized photocatalyst V 2 Bi‐O ‐BNT2Ag3 achieves a CO evolution rate of 109 µmol·g − 1 ·h − 1 in the absence of sacrificial agents, representing an enhancement of over 22‐fold compared with pristine Bi 12 O 17 Cl 2 nanosheets. These findings highlight the in situ evoluted vacancy pair coupled with metal sites as a promising strategy for designing advanced photocatalysts for selective CO 2 conversion.