The copper species derived from the two distinct phase structures after catalyst reconstruction exhibit unique functionalities. CCB enhances the adsorption of intermediate *CO, while CuO facilitates the H₂O decomposition to provide protons for the formation of *CHO, synergistically promoting the coupling of *CO–*CHO.

Abstract

The electrochemical reduction of carbon dioxide (CO₂) into multicarbon (C₂₊) products via copper-based catalysts presents a promising approach for enhancing the high-value utilization of CO₂. However, achieving high selectivity for C₂₊ products remains a significant challenge. In this study, we have engineered a copper-based biphasic catalyst comprising both copper carbonate basic and copper oxide (CCB/CuO), which demonstrates superior selectivity for C₂₊ products. The restructured catalyst retains a loose, porous microsphere secondary structure, providing ample active space for reactants and intermediates. In situ infrared spectroscopy reveals that CuO facilitates the activation of H₂O to supply the requisite protons, while CCB enhances the adsorption of the intermediate *CO, synergistically contributing to the formation of C₂₊ products. As a result, the optimized CCB/CuO catalyst achieves Faradaic efficiency (FE) of 52.7% for C₂H₄ and 79.1% for C₂₊ products, with FE_C2H4 remaining above 40% for a duration of 10 h.