Ampere-Level Electrolytic Coproduction of Formate with Coupled Carbon Dioxide Reduction and Selective Methanol Oxidation

Abstract

The electrocatalytic oxidation of small organic molecules presents a compelling approach for environmentally friendly and value-added chemical production, especially when coupled with high-efficiency carbon dioxide reduction. However, significant challenges persist in achieving industrial-scale current densities while ensuring optimal selectivity, activity, and cycle stability of the electrocatalyst. Here, we report the high performance of the Au/NiOOH@Ni heterojunction foam electrode in selective methanol oxidation, which efficiently pairs with cathodic carbon dioxide reduction to reach ampere-level coelectrolytic production of formate. The Au/NiOOH@Ni foam demonstrated ∼100% Faraday efficiency in the high current density range of 200–1200 mA/cm2 during half-cell methanol oxidation, and a total FEformate exceeding 180% was achieved under 1.20 A/cm2 using a coelectrolytic flow cell. In situ mechanistic investigations and theoretical calculations revealed that Au/NiOOH heterojunctions promote the formation and stabilization of high-valence active NiIII/IVOOH under both as-prepared and operando conditions through the interfacial NiIV-O*-Au structure, which continuously provides abundant active sites and oxygen sources (from partial water oxidation) for methanol-to-formate conversion while constructing a stable and efficient catalytic environment.