Inert Copper Incorporation Enables the High Activity and Durability of NiW Electrocatalyst for Alkaline Hydrogen Oxidation Reaction

Cu incorporation further refined the binding strength for intermediates (H* and OH*). Therefore, the resulting Cu_i-NiW exhibited outstanding HOR activity, yielding a peak power density of 340 mW cm⁻² in a noble metal-free fuel cell. Moreover, the alloy demonstrated robust durability with only a 5.7% current drop after 10000 cycles.

Abstract

The slow reaction kinetics of hydrogen oxidation reaction (HOR) on existing catalysts in alkaline hinders the commercialization of anion exchange membrane fuel cells (AEMFCs). In this work, a Cu-incorporated NiW alloy (Cu_i-NiW) without any platinum group metal (PGM) is designed and evaluated in both liquid cells and AEMFCs. This catalyst enabled the achievement of an electrochemical surface area-normalized exchange current density of 70 µA cm⁻² and robust stability, outperforming most PGM-free catalysts. Furthermore, the incorporation of Cu into other systems such as NiMo and NiV using the same method also showcased excellent HOR activity and durability. The fuel cells assembled with Cu_i-NiW as the anode and Pt/C or Fe-N-C as the cathode delivered peak power densities of 480 and 340 mW cm⁻², respectively. Experimental and theoretical studies reveal that the incorporated Cu is chemically inert but enhances the overall oxidation resistance of the catalysts. Moreover, it weakens hydrogen adsorption and promotes the adsorption of hydroxide ions, thereby enhancing the HOR activity significantly. These results may open a door for rational design of high-performance and durable PGM-free HOR catalysts.