Unraveling the synergy of dual heteroatom dopants in quantum dots for boosting photocatalytic CO2 reduction

Doping semiconductor quantum dots (QDs) with heteroatoms has emerged as a technologically important tool for tuning their electronic structure and improving their photocatalytic activities; however, the resulting systems still suffer from low efficiency towards photocatalytic CO₂ reduction. Herein, we report that co-doping CdS QDs with Se^2- and Ga³⁺ can boost the photocatalytic CO₂ reduction. The achieved CO evolution rate over Ga/Se co-doped CdS QDs is almost 20 times higher than that of pristine CdS QDs, and is also higher than some other reported QDs based photocatalysts for CO₂ photoreduction. The mechanism study uncovers that the co-doping of Se and Ga in CdS QDs can suppress the recombination of photogenerated electron–hole pairs and decrease the formation barrier of the key *COOH intermediate for promoting the CO₂ to CO conversion.