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

Abstract

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 (Vs-ZnS/OMNC) through an in situ thermal treatment strategy. The fs-TA spectrum elucidated that introducing sulfur vacancy (Vs) 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 Vs-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 Vs-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.