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 developed a compositional gradient AuCu bimetallic electrocatalyst (AuCu-g) featuring a robust Au–Cu⁰/Cu⁺ interface for stable and efficient CO₂ reduction. The unique gradient heterostructure and multicomponent tandem effect of the AuCu-g electrocatalyst not only endowed it with an impressive faradaic efficiency of 84.6% for ethanol production at an ultralow potential of −0.4 V versus RHE but also with extremely high stability over 75 h electrolysis. Strikingly, catalytically active Cu⁺ species persisted even after extended electrolysis. In situ spectroscopic results and theoretical calculations demonstrated that the Au–Cu⁰/Cu⁺ interface significantly enhanced *CO surface coverage and reduced the energy barriers for C–C coupling, thereby facilitating C–C dimerization for ethanol formation at low potentials. This work provides a new perspective for developing advanced CO₂ electroreduction catalysts to generate high-value products.