Engineering Au/Cu Interfaces to Promote *CO Spillover for High C2+ Selectivity in CO2 Electroreduction

Abstract

Multi-carbon (C2+) products hold significant economic value due to their high market demand and critical role as key precursors in advanced chemical synthesis. Although the tandem catalytic system has been proven to promote C2+ product selectivity, the transport efficiency of *CO intermediate between catalytic sites remains the critical factor governing the production of C2+ products. Herein, we design two tandem catalysts featuring gold nanoparticles anchored on metallic Cu surfaces with selective exposure of (100) and (111) facets (Au@Cu(100) and Au@Cu(111)), to investigate *CO spillover mechanisms in electrochemical CO2 reduction reaction (ECO2RR). Under optimized conditions, Au@Cu(100) achieves a maximum C2+ selectivity of 71% in a flow cell, significantly outperforming Au@Cu(111) (39%). Operando spectroscopic analyses reveal substantially enhanced *CO surface coverage on Au@Cu(100) relative to Au@Cu(111), while theoretical calculations demonstrate that the Au/Cu(100) interface lowers the energy barrier for *CO spillover toward the surface of Cu(100). This work establishes facet engineering as a pivotal strategy for optimizing *CO transport and utilization in selective CO2-to-C2+ conversion.