Oxygen-controlled photo-reforming of biopolyols to CO over Z-scheme CdS@g-C3N4

Photocatalytic carbon monoxide (CO) production from biomass is a sustainable route for achieving the carbon-neutral goal, but the current catalytic activity is low. One of the reasons is that the reaction is thermodynamically unfavorable (ΔG >0) in inert atmosphere. The reaction can be transformed into thermodynamically favorable (ΔG <0) in an oxygen-rich atmosphere but it leads to the deep degradation to CO2. Targeting this problem, we herein report an oxygen-controlled photo-reforming process to convert biomass-derived polyols into CO at room temperature. A CdS@g-C3N4 composite shows 48% yield of CO from glycerol in an appropriate O2 atmosphere, which is 13-fold of that in inert atmosphere. The Z-scheme heterojunction and core-shell structure of CdS@g-C3N4 not only efficiently promote charge separation and the enrichment of photogenerated electrons on the g-C3N4 shell but also facilitate the adsorption and activation of dioxygen. This study provides a new oxidative photo-reforming strategy to produce CO from biomass under mild conditions.