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.