DOI: 10.11648/j.ajee.20261403.12 ISSN: 2329-163X

Multicomponent Iridium-Based Alloy Catalysts for Enhanced Alkaline Hydrogen Oxidation Reaction

Yanfu Tong, Zhiyuan Liu, Xuejin Li, Wei Xing
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The sluggish kinetics of the hydrogen oxidation reaction (HOR) in alkaline media, primarily arising from the linear scaling relationship between H* and OH* adsorption energies on catalyst surfaces, remains a critical bottleneck for anion-exchange membrane fuel cells (AEMFCs). In this study, we propose a multifaceted approach to overcoming the current limitations of scaling by synthesising Ir-based ternary alloys with diverse oxophilic metals, including Mo, Ru, and Nb. The RuIrMo@MHCS catalyst, featuring a face-centred cubic single-phase solid solution with uniformly dispersed nanoparticles on hollow carbon spheres, exhibits a kinetic current density of 18.04 mA cm –2 at 50 mV overpotential and an exchange current density of 6.79 mA cm –2 . This is a significant improvement over the performance of commercial Pt/C, with factors of 6.14 and 5.66, respectively. Additionally, the catalyst demonstrates excellent long-term stability. X-ray photoelectron spectroscopy reveals electron transfer from Ir to Ru upon Ru doping. Density functional theory calculations demonstrate that Ru incorporation downshifts the d-band centre of Ir, thereby moderately weakening H* adsorption (ΔG H* = –0.38 eV) while enhancing OH* adsorption on Mo sites. This adaptable calibration of intermediate adsorption energies circumvents the linear scaling constraint and substantially promotes alkaline HOR kinetics. The findings of this study corroborate the hypothesis that multicomponent alloying is an effective strategy for synergistic optimisation of H* and OH* binding, thus providing a rational design pathway for high-performance alkaline HOR catalysts.

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