Oxygen vacancy-engineered BiOCl nanoflake with silver decoration for enhanced photocatalytic CO₂ reduction at solid-gas interface

Photocatalytic conversion of CO₂ into valuable chemicals is an attractive way to mitigate the greenhouse effect. However, the poor mass transfer of CO₂ in a liquid-phase reaction limits its conversion rate and carbon product selectivity. Here, we developed a gas-phase photocatalytic CO₂ reduction by Ag/BiOCl-oxygen vacancy nanoflakes (Ag/BiOCl-OV NFs) where the catalytic reaction occurs at the solid–gas interface between Ag/BiOCl-OV and CO₂/vapor reactants. Such a solid–gas system allows rapid adsorption/desorption of CO₂ on the surface of photocatalysts, enhanced light absorption and electron-hole separation, resulting in promoted photocatalytic reaction rate and CO selectivity compared to the solid–liquid systems. By supporting Ag/BiOCl-OV NFs on a photothermal substrate that has broadband light absorption to perform local heating for in-situ photothermal enhanced photocatalytic reaction. The synergistic effect of Ag nanoparticles, OVs and photothermal, the highly-selective CO product shows an evolution rate of 76 μmol g^-1h⁻¹, 17.6 times higher than that of pure BiOCl NFs.