Construction of an electron-transfer channel via Cu–O–Ni to inhibit the overoxidation of Ni for durable methanol oxidation at industrial current density

Abstract

The electrocatalytic methanol oxidation reaction (MOR) is a viable approach for realizing high value-added formate transformation from biomass byproducts. However, usually it is restricted by the excess adsorption of intermediates (CO_ad) and overoxidation of catalysts, which results in low product selectivity and inactivation of the active sites. Herein, a novel Cu–O–Ni electron-transfer channel was constructed by loading NiCuO_x on nickel foam (NF) to inhibit the overoxidation of Ni and enhance the formate selectivity of the MOR. The optimized NiCuO_x-2/NF demonstrated excellent MOR catalytic performance at industrial current density (E₅₀₀ = 1.42 V) and high faradaic efficiency of ∼100%, as well as durable formate generation up to 600 h at ∼500 mA cm⁻². The directional electron transfer from Cu to Ni and enhanced lattice stability could alleviate the overoxidation of Ni(III) active sites to guarantee reversible Ni(II)/Ni(III) cycles and endow NiCuO_x-2/NF with high stability under increased current density, respectively. An established electrolytic cell created by coupling the MOR with the hydrogen evolution reaction could produce H₂ with low electric consumption (230 mV lower voltage at 400 mA cm⁻²) and concurrently generated the high value-added product of formate at the anode.