A copper coordination polymer precatalyst with asymmetric building units for selective CO2-to-C2H4 electrolysis

Abstract

The electrochemical reduction of carbon dioxide (CO₂) to value-added multi-carbon products provides a feasible way to achieve carbon neutrality. However, enhancing the faradaic efficiency for a specific multi-carbon product like ethylene at high current densities is still a challenge. Herein, we report a Cu(II)-benzene-1,3,5-tricarboxylate coordination polymer (Cu-BTC-CP) with asymmetric building units, synthesized by a water etching strategy, for highly selective electrochemical CO₂-to-C₂H₄ conversion. The Cu-BTC-CP catalyst achieves an ethylene faradaic efficiency as large as 65.2 ± 3% at a high current density of 350 mA cm⁻² in a flow cell. Operando X-ray absorption fine structure analysis uncovers that the Cu-BTC-CP catalyst reconstructs to low-coordinated copper under reaction conditions. Density functional theory calculations further indicate that the low-coordinated Cu sites on metallic Cu surfaces are favorable for *CO intermediate coupling and promote CO₂ conversion to ethylene.