Compositional Gradient Au-Cu Bimetallic Heterostructures for Efficient Electroreduction of CO2 to Ethanol at Low Potential

Abstract

Upgrading carbon dioxide (CO2) to high-value fuels using renewable electricity presents a promising pathway for advancing sustainable chemical production and mitigating the greenhouse effect. Herein, we develop a compositional gradient AuCu bimetallic electrocatalyst (AuCu-g) featuring a robust Au-Cu0/Cu+ interface for stable and efficient CO2 reduction. Such unique gradient heterostructure and multicomponent tandem effect of the AuCu-g electrocatalyst not only endows an impressive faradaic efficiency of 84.62% for ethanol at an ultralow potential of −0.4 V versus RHE but also an extremely stability over 75 hours electrolysis. Strikingly, the catalytically active Cu+ species persist even after extended electrolysis. In situ spectroscopic results and theoretical calculations demonstrate that the Au-Cu0/Cu+ interface significantly enhances *CO surface coverage and reduces the energy barriers for C–C coupling, thereby facilitating C-C dimerization for ethanol formation at low potentials. The finding of this work provides a new perspective for the development of advanced catalysts to drive high-value products for CO2 reduction.