Photoredox coupling of benzyl alcohol oxidation with CO2 reduction over CdS/TiO2 heterostructure under visible light irradiation

Coupling CO2 photoreduction with selective organic synthesis offers a promising modus operandi to enable simultaneous utilization of photogenerated electrons and holes to realize solar fuels production and chemicals synthesis. Herein, we report a bifunctional zero-dimensional cadmium sulfide quantum dots-two-dimensional titanium dioxide nanosheets (CdS/TNS) heterostructure for photoredox-catalyzed coupling of C–C bond synthesis via selective oxidation of benzyl alcohol with CO2 photoreduction to CO under visible light. The compositing heterointerface is beneficial for the adsorption and activation of CO2, thereby promoting the photoreduction of CO2. Remarkably, the synergistic interaction between CdS and TNS tunes the selectivity of benzyl alcohol oxidation from carbonyl compound to the C–C coupled products. Mechanistic studies unveil that the generation of C–C coupled products processes via key radical •CH(OH)Ph intermediates. Theoretical simulations reveal that the weaker adsorption of •CH(OH)Ph radical over CdS/TNS than bare CdS contributes to the formation of highly selective C–C coupled products. The findings are expected to offer instructive guidance on rationally designing the dual-functional catalysts with efficient photoredox-catalyzed coupling reaction systems for integrating CO2 reduction with selective organic transformations.