Enhancing Acidic Oxygen Evolution Activity by Supporting Iridium Electrocatalysts on Tantalum Carbide

For a high-performance proton exchange membrane water electrolyzer (PEMWE), acidic oxygen evolution reaction (OER) electrocatalysts require highly dispersed iridium oxide (IrOx) nanoparticles. Although carbon-based materials have been explored as promising supports for IrOx nanoparticles, their limited stability under harsh oxidative and acidic PEMWE conditions remains a significant challenge. In this study, we report the synthesis and in situ characterization of active and durable IrOx electrocatalysts supported on electrochemically stable and electrically conducting tantalum carbide (TaC). When applied in a PEMWE, the IrOx/TaC electrocatalyst achieves a cell voltage of 1.71 V at 1.0 A cm–2, outperforming the commercial IrO2 catalyst (1.82 V at 1.0 A cm–2). Furthermore, the IrOx/TaC catalyst maintains a stable operation for 200 h at 0.5 A cm–2 with a low degradation rate of 36 μV h–1. Density functional theory calculations further confirm that Ir–O–Ta bond formation at the IrOx/TaC interface reduces the overpotential of the OER compared to IrO2. This study underscores the pivotal role of supporting IrOx over stable and conducting metal carbides, providing guidance for the design of advanced acidic OER catalysts.