CuO_x-ZrO₂-TiO_x Composite Interfaces with Strong Lewis Acid Activity for Electrooxidation of Methane to Acetic Acid

The electrochemical conversion of methane (CH₄) to valuable oxygenates is an attractive approach to utilize abundant natural gas, however, the chemical inertness of CH₄ and its low solubility in electrolytes impede effective electrooxidation. Enhancing the adsorption and activation of CH₄ on catalysts is crucial for electrocatalytic methane oxidation reaction (eMOR). In this study, we developed the CuO_x-ZrO₂-TiO_x composite catalyst for the selective electrooxidation of CH₄ to CH₃COOH. The ZrO₂-TiO_x was in situ synthesized on Ti substrates via the hydrothermal reaction of TiO₂ nanowires with H₂C₂O₄ and Zr(NO₃)₄. Subsequently, CuO_x was uniformly disposed on ZrO₂-TiO_x with the assistance of polyvinylpyrrolidone (PVP) and citric acid. The prepared electrode achieves the Faradaic efficiency (FE) of 60.1% for CH₃COOH at the current density of 10.8 mA cm^-2, corresponding to the generation rate of 3312.5 µmol g_cat ^-1 h^-1. Mechanism studies confirm that the synergistic effect of CuO_x and ZrO₂-TiO_x interfaces enhances the efficiency of eMOR. CuO_x oxidizes H₂O to produce hydroxyl radicals (*OH) and ZrO₂-TiO_x interfaces with strong Lewis acid activity adsorb and activate CH₄. The CuO_x and ZrO₂-TiO_x interfaces synergistically oxidize CH₄ to generate a series of intermediates (*CH₃, *CH₃O, *CH₂O, *COOH), promoting C-C coupling to produce CH₃COOH.