Electrocatalytic C–C coupling of CO2 and formaldehyde to synthesize acetate via membrane electrode assembly†

Abstract

The electrocatalytic CO₂ reaction with other gases to synthesize value-added products at high current densities is challenging due to the limited diffusion rate for low-solubility gases in aqueous electrolytes. To enhance the mass transfer process, herein, a membrane electrode assembly (MEA) electrolyzer is employed to achieve high-rate electrochemical C–C coupling of CO₂ and gaseous formaldehyde. Based on the simultaneous gas-phase delivery of reactants to the catalytic surface, an acetate production rate of 654 mg L⁻¹ h⁻¹ is achieved at a current density over 150 mA cm⁻² on a Cu-MOF coated Cu₂O catalyst. In situ FT-IR, Raman spectroscopy, and in situ XAFS combined with DFT suggest that the energy barrier of C–C coupling between *CO and *CH₂OH is significantly lowered due to the insertion of Cu-MOF, thus promoting the production of acetate. This work provides a novel strategy for electrochemical treatment of waste gas coupling to synthesize high-value products with potential industrial applications.