Sulfur vacancy-rich ZnS on ordered microporous carbon frameworks for efficient photocatalytic CO₂ reduction

ZnS has garnered significant attention as a versatile photocatalyst in the field of CO₂ reduction. However, its photocatalytic efficiency has been hindered by its high charge recombination rates and sluggish reaction kinetics. Herein, we demonstrate a highly efficient CO₂ photoreduction on well-designed S-deficient ZnS nanoparticles within an ordered mesoporous N-doped carbon framework (V_s-ZnS/OMNC) through an in situ thermal treatment strategy. The fs-TA spectrum elucidated that introducing sulfur vacancy (V_s) effectively promoted the separation of photogenerated charges in ZnS/OMNC and significantly improved its reaction kinetics. In situ DRIFTS spectroscopy and DFT calculations revealed that these S vacancies led to charge accumulation on neighboring Zn atoms, enabling effective adsorption and activation of CO₂ molecules. Particularly, the vacancy strategy also effectively lowered the energy barrier for forming the key intermediate *COOH. Therefore, the CO evolution rate of V_s-ZnS/OMNC reached 712.1 μmol·g⁻¹·h⁻¹, which is 2.84 times higher than that without sulfur vacancy (250.74 μmol·g⁻¹·h⁻¹). Its CO₂ reduction performance surpassed most ZnS-based photocatalysts reported previously. Additionally, the V_s-ZnS/OMNC exhibited outstanding stability without obvious degradation after five reaction cycles. This study provides insights into developing advanced photocatalysts through vacancy defect engineering combined with ordered mesoporous carbon structures.