Atomically thin high-entropy oxides via naked metal ion self-assembly for proton exchange membrane electrolysis.

Zhang, Tao; Liu, Qingyi; Bao, Haoming; Wang, Mingyue; Wang, Nana; Zhang, Bao; Fan, Hong Jin · Nat Commun · 2025

basic_science · Level V

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Abstract

Designing efficient Ruthenium-based catalysts as practical anodes is of critical importance in proton exchange membrane water electrolysis. Here, we develop a self-assembly technique to synthesize 1 nm-thick rutile-structured high-entropy oxides (RuIrFeCoCrO<sub>2</sub>) from naked metal ions assembly and oxidation at air-molten salt interface. The RuIrFeCoCrO<sub>2</sub> requires an overpotential of 185 mV at 10 m A cm<sup>-2</sup> and maintains the high activity for over 1000 h in an acidic electrolyte via the adsorption evolution mechanism. We discuss the role of each element in the RuIrFeCoCrO<sub>2</sub> and find that the Cr, Co, and Ir sites contribute to the catalytic activity, while the Cr atoms weaken the Ru-O bond covalency and improves the catalyst stability. The assembled proton exchange membrane electrolyzer operates stably for more than 600 h at a large current of 1 A cm<sup>-2</sup>. The naked ion assembly demonstrated in this work may provide an effective pathway for the controlled synthesis of a diversity of high-entropy materials.