Synthesis of NiMoW ternary alloy to boost hydrogen oxidation reaction in alkaline medium

Abstract

The unsatisfactory activities of nickel-based electrocatalysts in the alkaline hydrogen oxidation reaction (HOR) pose a crucial challenge in the development of hydroxide-exchange membrane fuel cells (HEMFCs). Generally, alloying Ni with Mo or W efficiently promotes HOR in alkaline media by reducing the hydrogen binding energy and increasing the hydroxyl binding energy. However, the alkaline HOR activities of binary alloys still do not meet industrial requirements. Therefore, herein, we report that the alkaline HOR activity of the Ni-based electrocatalyst can be enhanced by preparing a NiMoW ternary alloy (Ni76Mo78W) fabricated via a hydrothermal process, followed by annealing under a H2 atmosphere. This as-prepared nickel foam-supported Ni76Mo78W alloy exhibits excellent HOR catalytic activity (the current density reaches 6.6 mA cm−2 at 100 mV vs. RHE, approximately twice that of the Pt/C electrocatalyst), fast kinetics (exchange current density j0 of 3.12 mA cm−2), and ultrahigh stability (maintenance of the current density over 80 h). Detailed characterizations reveales that the charge transfer between the alloy components presumably tunes the electronic structure of the alloy and ultimately promotes the HOR.