Preparation of cadmium and sulfur deficient CdS for photocatalytic reduction of CO₂

Converting CO₂ into C1 chemicals such as CO，CH₄，and CH₃OH using solar energy as the driving force is an effective strategy to alleviate the greenhouse effect and energy shortage crisis. However，single-component catalysts face challenges in photocatalytic CO2 reduction including limited light absorption capacity，easy recombination of photogenerated carriers，and low overall catalytic efficiency. Constructing high-efficiency catalysts to improve photocatalytic CO₂ reduction performance is therefore crucial. In this study，CdS-0.25 with sulfur vacancies and CdS-2 with cadmium vacancies are successfully synthesized via a hydrothermal method by adjusting the ratio of cadmium and sulfur precursors. Characterization analysis shows that compared with CdS-2 with cadmium vacancies，CdS-0.25 with sulfur vacancies exhibits stronger solar light absorption capacity and effectively suppresses the recombination of photogenerated electrons and holes. First-principles calculations demonstrate that sulfur vacancies have better adsorption capacity for CO₂ reactant molecules. The production rates of CO，CH₄，and H₂ from CO₂ reduction over CdS-0.25 are 1.69，0.41，0.11 µmol/（g·h），respectively. These values are 15.8，2，and 1.2 times higher than those of CdS-2. This work provides insights for the design of high-efficiency defective materials for photocatalytic CO₂ reduction.