Polyethyleneimine coated AgInS2 quantum dots for efficient CO2 photoreduction to C2H6

• A series of PEI coated AgInS 2 quantum dots are designed and synthesized for photocatalytic CO 2 reduction to C 2 H 6 . • The yield of C 2 H 6 is 63 μmol g -1 in 6 h, and the electron selectivity is 30.3 %. • The coated PEI effectively promotes the accumulation of photogenerated electrons on the catalyst. • The CO-enriched environment caused by Ag boosts C-C coupling on AgInS 2 quantum dots. Quantum dots exhibit great potential in photocatalytic CO 2 conversion into value-added fuels to achieve a carbon-neutral society, owing to their unique optical properties and tunable surface chemistry. However, the generation of multi-carbon hydrocarbon products remains a grand challenge. Herein, polyethyleneimine (PEI) coated AgInS 2 quantum dots (AgInS 2 @PEI QDs) are designed for the photo-catalytic conversion of CO 2 to C 2 products. It is found that the yield and selectivity of C 2 H 6 can be significantly enhanced by regulating the content of Ag and PEI in AgInS 2 @PEI QDs. Under the optimal conditions, C 2 H 6 yield reaches 63 μmol g -1 , and the electron selectivity is 30.3 %. A mechanistic study reveals that PEI effectively promotes the accumulation of photogenerated electrons, and the CO-enriched local environment caused by Ag boosts C C coupling on asymmetric bimetallic sites. This work offers new insight on the design of efficient quantum dot photocatalysts for CO 2 conversion to C 2 products.