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Lowering iridium (Ir) loading without sacrificing activity and durability is critical to the future development of proton exchange membrane water electrolyzer (PEMWE). Here, we present the synthesis of iridate-derived, layered iridium oxide microparticles (dubbed p-L-IrO2) with a high open porosity of approximately 74% and their structural advantages for the fabrication of efficient, durable, low-Ir-loading anode catalytic layer in PEMWE. The p-L-IrO2 material is synthesized by an easily scalable route involving acid treatment of alkali metal salt-templated iridates that form in mixed alkali metal nitrates-hydroxides at low temperature. The combination of high-porosity morphology and layered structure in the material preferentially exposes a high density of hydroxylated edge sites, which are catalytically active and stable to achieve the oxygen evolution reaction via a structurally hydroxyl group-participated adsorbate evolution mechanism. This material is further demonstrated to enable the fabrication of low-Ir-loading anode catalytic layers in PEMWE, which can afford excellent catalytic performance (2.7 A cm-2@1.9 V@80 °C; membrane: Nafion™ N115) due to the simultaneous reduction of activation and mass transport losses and retention of catalytic activity for 2300 h at 1.0 A cm-2 current density. © 2024 Chinese Chemical Society.
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