NdO-Intensified Dual-Site Synergy in IrMnO_x for Acidic Oxygen Evolution

The development of low-iridium (Ir) electrocatalysts for proton exchange membrane water electrolyzers (PEMWEs) remains a significant challenge. In this work, we present an IrNdMnO_x catalyst synthesized by incorporating neodymium oxide (NdO_x) into an IrMnO_x matrix, forming a triple solid-solution oxide. The resulting IrNdMnO_x catalyst achieves an impressive mass-specific activity of 769 A g^-1 at an ultralow Ir loading of 0.09 mg_Ir cm^-2, with overpotential of 331 mV @ 100 mA cm^-2-substantially outperforming conventional IrO₂ catalysts (416 mV @100 mA cm^-2). In a PEMWE cell, the IrNdMnO_x anode sustained stable operation at 1 A cm^-2 for over 800 h at ∼1.78 V. Differential electrochemical mass spectroscopy measurements and X-ray absorption spectroscopy analysis indicate that doping with large-ionic-radius neodymium (Nd) creates an asymmetric Nd-O-Ir-O-Mn coordination structure. This unique configuration not only shortens the Ir-Mn distance to promote the oxygen-oxygen radical coupling mechanism (ORCM) but also finely tunes the electronic structure of Ir sites, reconciling high optimal catalytic activity with robust stability. This work establishes NdO_x doping as a strategy to enhance the activity, stability, and cost-efficiency of Ir-based catalysts for acidic OER, advancing the development of sustainable hydrogen production.