Neodymium-doped hollow Ir/IrO2 nanospheres with low geometric iridium density enable excellent acidic water oxidation performance

Reducing the Ir loading while preserving catalytic performance and mechanical robustness in anodic catalyst layers remains a critical challenge for the large-scale implementation of proton exchange membrane water electrolysis (PEMWE). Herein, we present a structural engineering strategy involving neodymium-doped Ir/IrO 2 (Nd–Ir/IrO 2 ) hollow nanospheres with precisely adjustable shell thickness and cavity dimensions. The optimized catalyst demonstrates excellent oxygen evolution reaction (OER) performance in acidic media, achieving a remarkably low overpotential of 259 mV at a benchmark current density of 10 mA cm −2 while exhibiting substantially enhanced durability compared to commercial IrO 2 and Ir/IrO 2 counterparts. Notably, the Nd–Ir/IrO 2 catalyst delivers a mass activity of 541.6 A g Ir −1 at 1.50 V vs . RHE, representing a 74.5-fold enhancement over conventional IrO 2 . Comprehensive electrochemical analysis and advanced characterization techniques reveal that the hierarchical hollow architecture simultaneously addresses multiple critical requirements: (i) abundant exposed active sites enabled by an enhanced electrochemical surface area , (ii) optimized mass transport pathways through engineered porosity, and (iii) preserved structural integrity via a continuous conductive framework, collectively enabling significant Ir loading reduction without compromising catalytic layer performance. Fundamental mechanistic investigations further disclose that Nd doping induces critical interfacial Nd–O–Ir configurations that stabilize lattice oxygen, together with intensified electron effect among mixed valent Ir that inhibits the overoxidation of Ir active sites during the OER process, synergistically ensuring enhanced catalytic durability. Our work establishes a dual-modulation paradigm integrating nanoscale architectural engineering with atomic-level heteroatom doping, providing a viable pathway toward high-performance PEMWE systems with drastically reduced noble metal requirements. Neodymium-doped Ir/IrO 2 hollow structure significantly reduces the geometric loading of Ir in anodic catalyst layer of proton exchange membrane water electrolysis without compromising catalytic layer performance. Nd doping induces critical interfacial Nd–O–Ir configurations that stabilize lattice oxygen, while intensified electron effect among mixed valent Ir inhibits the overoxidation of Ir active sites, synergistically ensuring the enhanced catalytic durability.