Asymmetric Copper‐Sulphur Sites Promote C–C Coupling for Selective CO2 Electroreduction to C2 Products

Abstract

AbstractSustainable multicarbon e‐chemicals are of particular interest due to their potential future, high market values, and demand. In the direct electrocatalytic formation of multicarbon e‐chemicals from CO2, the elementary C–C coupling by CO dimerization is considered the rate‐limiting step. Here, a generalized surface structural design principle of asymmetric metal pair sites is proposed, explored, and experimentally tested in order to promote CO dimerization on surfaces. First a computational model of N‐doped Cu2S layers featuring adjacent, electronically asymmetric Cuδ1+‐Cuδ2+ (0 < δ1+ < δ2+ < 1) metal atomic pairs evidenced by their non‐uniform charge distribution is considered. The electronic asymmetry resulted in distinct CO adsorption energies and the associated self‐adjusting structures, which lowered C–C coupling energy barriers significantly. The computational hypotheses are experimentally tested using X‐ray photoelectron spectroscopy of Cu‐N moieties within N‐doped Cu2S layers. In‐situ Fourier‐transform infrared spectroscopy confirms linear *CO and *CO‐CO adsorption configuration by the peaks of ≈2080 and 1920 cm−1, respectively. After N‐doping, the catalytically C2 faradaic efficiency can significantly be elevated to 14.72% due to the promotion of C–C coupling.