Construction of an electron-transfer channel <i>via</i> 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 _<i>x</i> on nickel foam (NF) to inhibit the overoxidation of Ni and enhance the formate selectivity of the MOR. The optimized NiCuO _<i>x</i> -2/NF demonstrated excellent MOR catalytic performance at industrial current density (<i>E</i> ₅₀₀ = 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 _<i>x</i> -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.