In situ growth of Ag₂S quantum dots on SnS₂ nanosheets with enhanced charge separation efficiency and CO₂ reduction performance

Photocatalytic CO2 reduction to carbon fuels is a desirable solution to replace conventional fossil fuels. Herein, SnS2 nanosheets (NSs) were fabricated via a facile hydrothermal method, and they transformed to thinner and more homogeneous dispersions with gradually increasing hydrothermal temperature to 200 °C because of the hydrothermal self-exfoliation effect. The obtained SnS2-200 NSs displayed optimum photoelectrochemical properties with an excellent light-driven CO production rate. After modification with Ag2S quantum dots (QDs) by an in situ cation-exchange reaction, the SnS2/Ag2S-50 nanocomposites bridged with Sn–S–Ag bonds exhibited 7-fold higher CO/CH4 (48.7/3.18 μmol g−1 h−1) production than pristine SnS2-200. The intimate contact between SnS2-200 NSs and Ag2S through co-shared S atom layers facilitates the photoelectron transfer to the SnS2-200 surface and then to Ag2S QDs for CO2 reduction. This study presents a novel example for heterostructure design and offers new opportunities for exploring efficient photocatalytic CO2 reduction systems for solar-to-chemical energy conversion.