Multifunctional Conductive Polymer Modification for Efficient CO₂ Electroreduction in Acidic Electrolyte

Electrode-electrolyte interfacial modification by hydrophobic molecules represents a promising strategy for suppressing competing proton reduction in acidic electrocatalytic carbon dioxide reduction reactions (CO₂RR), meanwhile sacrificing extra overpotential due to increased ohmic resistance. Herein, a multifunctional conductive polymer, polyaniline modified by p-aminobenzenesulfonic acid (ABSA-polyaniline), is constructed between Cu catalyst layer and electrolyte to simultaneously create an ideal microenvironment for CO₂RR and enhance the charge transfer and ion transport processes at the electrochemical reaction interface. This polymer layer balances the local hydrophobicity, promotes CO₂ adsorption and activation, and regulates the mass transport of K⁺, H⁺, and OH⁻ ions, thus significantly enhancing the CO₂RR kinetics in acidic medium, yielding a high Faraday efficiency (FE = 81%) for multicarbon products at 600 mA cm⁻². More importantly, compared with commonly used hydrophobic molecules, the conductive nature of ABSA-PANI helps to reduce the ohmic resistance of the electrode, leading to notably lowered cathode overpotential at industrial-grade current density and improve cathode energy efficiency over a wide potential window. This work sheds light on the development of highly efficient acidic CO₂RR systems, especially for those with low alkali cation concentrations and low CO₂ concentrations.