The surface electronic structures of catalysts play a
crucial role
in CO2 adsorption and activation. Here, sulfur vacancies
are introduced into CuInS2 nanosheets (Vs-CuInS2) to evaluate the effect of electronic structures at the surface-active
sites on the electrochemical CO2 reduction reaction (CO2RR). Vs-CuInS2 exhibits a significant
disparity in the highest FEformate/FECO (6.50)
compared to that of CuInS2 (1.86). Specifically, the maximum
current density (Jmax) of carbon products
on Vs-CuInS2 is 78.78 mA cm–2, and a Faraday efficiency of carbon products (FEcarbon 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 Vs-CuInS2. In addition, the regulation of electronic structures
on Vs-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.