Local Hollandite Phase Inducing Oxygen Path Mechanism Enables Durable PEM Electrolysis

ABSTRACT Large‐scale proton‐exchange‐membrane water electrolyzers (PEMWEs) are urgently needed for green hydrogen production, however, their development is largely hindered by the use of high‐loading iridium in the anode. While amorphous IrO x catalysts with high activity exist, they typically follow either the lattice oxygen mechanism compromising stability, or the adsorbate evolution mechanism suffering from a high overpotential limit. Oxide path mechanism (OPM) offers a promising alternative by enabling direct * O─ * O coupling, but its activation in the pure IrO x system remains challenging given the long distance between adjacent Ir atoms. Herein, we report a class of (La)IrO x porous amorphous catalyst with OPM pathway, featuring local unconventional hollandite phase and abundant water molecules inside its lattice tunnels. We demonstrate that such a unique short‐range ordered structure can induce shortened Ir–Ir edge distance and highly‐active Ir ≥5+ species, both contributing to desirable OPM for greatly enhanced catalytic performances. The as‐assembled PEMWE achieves a cell voltage of 1.62 V at 1 A cm −2 with a low loading of 0.2 mg Ir cm −2 , and can operate stably over 500 h at industry‐level current density. The accelerated stress test further validates its durability advantage at even lower 0.1 mg Ir cm −2 loading, which validates its potential as a viable anode solution for durable low‐iridium PEMWEs.