Ir/IrOx-WO3 nanocomposites with direct catalyst-support junctions for low-iridium proton exchange membrane water electrolysis

초록

Proton exchange membrane water electrolysis (PEMWE) is considered a promising technology for sustainable green hydrogen production, but it is still limited by the sluggish acidic oxygen evolution reaction (OER), which requires scarce Ir-based catalysts. Herein, Ir/IrOx-WO3 nanocomposites were designed to reduce Ir loading in PEMWE anodes. By controlling the Ir/W ratio, the density of direct Ir/IrOx-WO3 junctions was systematically tuned. Ir/IrOx-WO3 nanocomposite with an Ir content of 30 wt% (IW-30) exhibited the highest acidic OER activity, achieving an overpotential of 278.3 mV at 10 mA cm-² and a mass activity of 457 A gIr-¹ (1.55 V vs. RHE). Operando X-ray absorption spectroscopy revealed that residual metallic Ir in IW-30 was oxidized more rapidly during acidic OER than in IW-55, indicating that direct Ir/IrOx-WO3 junctions facilitate the formation of catalytically active oxidized Ir species. In PEMWE tests, IW-30 delivered 3 A cm-² at 1.9 V and maintained stable operation for 450 h at 2 A cm-² with an ultralow Ir loading of 0.25 mgIr cm-². These findings reveal that direct Ir/IrOx-WO₃ junctions accelerate Ir oxidation under OER conditions, providing a viable strategy for developing low-Ir and durable PEMWE anode catalysts. © 2026 Elsevier B.V.

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