3D Heterostructured Copper Electrode for Conversion of Carbon Dioxide to Alcohols at Low Overpotentials

Abstract Active and cost‐effective catalyst materials are required for electrochemical CO₂ reduction reactions (CO₂RR) which, to date, are proving elusive. Here, the direct electrochemical conversion of CO₂ to liquid products with a high overall Faradaic efficiency (FE) by utilizing a unique 3D, heterostructured copper electrode (referred as Cu sandwich) that is obtained via a simple two‐step treatment of commercially available copper foam is reported. The designed catalyst achieves an FE toward liquid products of >50% at an applied potential as low as −0.3 V versus reversible hydrogen electrode. The improved selectivity of the heterostructured Cu sandwich electrode at low overpotentials is attributed to the greater exposure of engineered Cu⁺/Cu²⁺ interfaces (present on composite nanowires) and higher oxygen vacancy defects. Moreover, the rationally designed heterostructures prevent the Cu₂O species from being reduced during CO₂RR enabling the catalyst to demonstrate enhanced CO₂RR activity with prolonged stability.