Selective electrooxidation of methane to formic acid by atomically dispersed CuOx and its induced Lewis acid sites on V2O5 in a tubular electrode

Abstract

Electrocatalytic oxidation of methane (CH4) to value-added chemicals is an attractive approach to directly use natural gas. Herein, we synthesize CuOx/V2O5 composite catalysts in the hollow porous titanium tubes for selective electrooxidation of CH4 to formic acid (FA). The complexed Cu2+ ions achieve atomic-level dispersion on the V2O5 surface, and then transform into atomically dispersed CuOx during heat treatment, forming Cu-O-V bonds. Interestingly, atomically dispersed CuOx simultaneously induces the generation of abundant oxygen vacancies with strong Lewis acid activity. Moreover, the porous tubular electrode realizes the directional transmission of CH4 gas and create rich gas-liquid-solid three-phase reaction interfaces. The optimized active components and electrode structure achieve the Faradaic efficiency of FA up to 92 % at the current density of 14.4 mA cm−2. Mechanism research indicates that atomically dispersed CuOx and its induced Lewis acid sites promote the electrooxidation of H2O and the adsorption-activation of CH4 to produce *OH and *CH3.