Enabling Visible-Light-Driven Selective CO2 Reduction by Doping Quantum Dots: Trapping Electrons and Suppressing H2 Evolution.

Quantum dots (QDs), a class of promising candidates for harvesting visible light, generally exhibit low activity and selectivity towards photocatalytic CO2 reduction. Functionalizing QDs with metal complexes (or metal cations through ligands) is a widely used strategy for improving their catalytic activity; however, the resulting systems still suffer from low selectivity and stability in CO2 reduction. Herein, we report that doping CdS QDs with transition-metal sites can overcome these limitations and provide a system that enables highly selective photocatalytic reactions of CO2 with H2 O (100 % selectivity to CO and CH4 ), with excellent durability over 60 h. Doping Ni sites into the CdS lattice leads to effective trapping of photoexcited electrons at surface catalytic sites and substantial suppression of H2 evolution. The method reported here can be extended to various transition-metal sites, and offers new opportunities for exploring QD-based earth-abundant photocatalysts.