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 (SnS2−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 SnS2−x/NHCS with its CO2RR performance, and proposes a convenient route to boost the CO2 activation capability and conductivity of electrocatalysts simultaneously.