Adjusted Preferential Adsorption of Intermediates via Regulation of the Electronic Structure during the Electrocatalytic CO₂ Reduction Process

The surface electronic structures of catalysts play a crucial role in CO₂ adsorption and activation. Here, sulfur vacancies are introduced into CuInS₂ nanosheets (V_s-CuInS₂) to evaluate the effect of electronic structures at the surface-active sites on the electrochemical CO₂ reduction reaction (CO₂RR). V_s-CuInS₂ exhibits a significant disparity in the highest FE_formate/FE_CO (6.50) compared to that of CuInS₂ (1.86). Specifically, the maximum current density (J_max) of carbon products on V_s-CuInS₂ is 78.78 mA cm^–2, and a Faraday efficiency of carbon products (FE_{carbon products}) of ≥80% is achieved in 600 mV wide potential windows. In situ Raman measurements and density functional theory calculations elucidate the origin of the apparent alterations in the carbon product selectivity. The introduction of sulfur vacancies realizes the controllable regulation of the local electronic density around the metal active sites, inducing the transformation of *COOH and *OCHO from competitive adsorption on CuInS₂ to specific adsorption on V_s-CuInS₂. In addition, the regulation of electronic structures on V_s-CuInS₂ inhibits *H adsorption. This work reveals the transfer of adsorption of CO₂RR intermediates via regulation of the electronic structure, complementing the understanding of the mechanism for the enhanced CO₂RR.