Binding\nSite Diversity Promotes CO₂ Electroreduction\nto Ethanol

Abstract

The\nelectrochemical reduction of CO₂ has seen many record-setting\nadvances in C₂ productivity in recent years. However, the\nselectivity for ethanol, a globally significant commodity chemical,\nis still low compared to the selectivity for products such as ethylene.\nHere we introduce diverse binding sites to a Cu catalyst, an approach\nthat destabilizes the ethylene reaction intermediates and thereby\npromotes ethanol production. We develop a bimetallic Ag/Cu catalyst\nthat implements the proposed design toward an improved ethanol catalyst.\nIt achieves a record Faradaic efficiency of 41% toward ethanol at\n250 mA/cm² and −0.67 V vs RHE, leading to a cathodic-side\n(half-cell) energy efficiency of 24.7%. The new catalysts exhibit\nan in situ Raman spectrum, in the region associated with CO stretching,\nthat is much broader than that of pure Cu controls, a finding we account\nfor via the diversity of binding configurations. This physical picture,\ninvolving multisite binding, accounts for the enhanced ethanol production\nfor bimetallic catalysts, and presents a framework to design multimetallic\ncatalysts to control reaction paths in CO₂ reductions toward\ndesired products.