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 (COad) 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 (E 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 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.