ReS₂ Nanosheets with In Situ Formed Sulfur Vacancies for Efficient and Highly Selective Photocatalytic CO₂ Reduction

Artificial photosynthesis can provide valuable fuels and positively impact greenhouse effects, via transforming carbon dioxide (CO₂) and water (H₂O) into hydrocarbons using semiconductor-based photocatalysts. However, the inefficient charge-carrier dissociation and transportation as well as the lack of surface active sites are two major drawbacks to boosting their activity and selectivity in photocatalytic CO₂ reduction. Recently, ReS₂ has received tremendous attention in the photocatalysis area due to its intriguing physicochemical properties. Nevertheless, the application of ReS₂ in photocatalytic CO₂ reduction is scarcely covered. Herein, a heterojunction formed between ReS₂ nanosheets and CdS nanoparticles is reported, achieving an apparently raised CO production of 7.1 μmol g⁻¹ and high selectivity of 93.4%. The as-prepared ReS₂/CdS heterojunction exhibits strengthened visible-light absorption, high-efficiency electron–hole pair separation/transfer, and increased adsorption/activation/reduction of CO₂ on in situ created sulfur vacancies of ReS₂, thus all favoring CO₂ photoreduction. These are corroborated by advanced characterization techniques, e.g., synchrotron-based X-ray absorption near-edge structure, and density functional theory–based computations. The findings will be of broad interest in practical design and fabrication of surface active sites and semiconductor heterojunctions for applications in catalysis, electronics, and optoelectronics.