ReS Nanosheets with In Situ Formed Sulfur Vacancies for Efficient and Highly Selective Photocatalytic CO Reduction.

Artificial photosynthesis can provide valuable fuels and positively impact greenhouse effects, via transforming carbon dioxide (CO) and water (HO) 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 CO reduction. Recently, ReS has received tremendous attention in the photocatalysis area due to its intriguing physicochemical properties. Nevertheless, the application of ReS in photocatalytic CO reduction is scarcely covered. Herein, a heterojunction formed between ReS nanosheets and CdS nanoparticles is reported, achieving an apparently raised CO production of 7.1 μmol g and high selectivity of 93.4%. The as-prepared ReS/CdS heterojunction exhibits strengthened visible-light absorption, high-efficiency electron-hole pair separation/transfer, and increased adsorption/activation/reduction of CO on in situ created sulfur vacancies of ReS, thus all favoring CO 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.