Integrating vacancy engineering and energy-level adapted coupling of electrocatalyst for enhancement of carbon dioxide conversion

CO₂ activation capability and conductivity of electrocatalysts are two crucial factors to address the high activation barrier and slow kinetics of CO₂ reduction reaction (CO2RR). Still, substantial promotion of both factors remains challenging. Herein, we report sulfur-deficient tin disulfide covered nitrogen-doped hollow carbon spheres (SnS_2−x/NHCS) as electrocatalyst for CO2RR. Combining experimental analysis with calculations, we demonstrate that the S vacancies and energy-level adapted coupling can decrease the reaction barrier, increase the CO₂ adsorption capacity and affinity with the intermediate, and promote the conductivity, delivering a current density of 35.3 mA cm⁻² at − 1.2 V vs. reversible hydrogen electrode (RHE) and a Faradaic efficiency for formate > 80% in a large potential range from − 0.8 to − 1.2 V (vs. RHE). This work unravels the relationship of the vacancy engineering/hybrid coupling of SnS_2−x/NHCS with its CO2RR performance, and proposes a convenient route to boost the CO₂ activation capability and conductivity of electrocatalysts simultaneously.