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.