Harnessing interfacial Cl‾ ions for concurrent formate production at industrial level via CO₂ reduction and methanol oxidation

Abstract

The efficient electrocatalytic conversion of CO2 to formate is often impeded by the high energy requirements of the oxygen evolution reaction (OER) and the limited activity and selectivity of CO2 reduction reaction (CO2RR). Herein, a novel strategy to enhance formate production by substituting the OER with the methanol oxidation reaction (MOR) and optimizing the cathodic microenvironment with interfacial Cl− ions is presented. Through theoretical analysis, binder-free Bi and NiOOH electrodes that achieve remarkable Faradaic efficiencies (FEformate) exceeding 90% at current densities of 50–250 mA·cm−2 for CO2RR and MOR, respectively, are identified. These combined experimental and theoretical investigations demonstrate that interfacial Cl− enrichment on the Bi electrode modulates the local electronic structure, fostering a microenvironment conducive to CO2RR. The Bi–NiOOH full cell maintains a FEformate above 90% at industry-level current densities (100–300 mA·cm−2), enabling concurrent formate electrosynthesis at both electrodes. This work highlights the critical role of local anion environments in electrocatalysis and provides a strategic framework for the synergistic engineering of electrochemical systems. Graphical abstract: [Figure not available: see fulltext.]