Plasma‐Assisted Fabrication of Defect‐Rich Tri‐Phase NiRu Alloy/Carbon Shell Heterostructure with Ni‐O‐Ru Interfaces for Efficient and Durable Anion‐Exchange‐Membrane Water Electrolyzers

This study presents a synergistic strategy combining plasma‐assisted magnetron co‐sputtering and thermal oxidation of a carbon shell to fabricate a self‐supported FL‐C@NiRu/NCNT@CC electrode with a tri‐phase “NiRu alloy core–graphitic shell–Ni‐O‐Ru interfacial boundary” structure. Sub‐nanometer‐scale uniform alloying of Ni and Ru via radio‐frequency/direct‐current plasma magnetron co‐sputtering enables precise modulation of metal electronic structure and interfacial charge‐distribution, activating d‐orbital coupling and interface‐polarization. An in‐situ conductive graphite‐shell is deposited on alloy particles, followed by mild air thermal‐oxidation, which thins the carbon shell, reconstructs boundary defects, and induces the formation of a Ni‐O‐Ru heterostructure. This enhances interfacial coupling and intrinsic oxygen‐evolution‐reaction (OER)/hydrogen‐evolution‐reaction (HER) activity. Consequently, the electrode exhibits excellent bifunctional electrocatalytic performance in alkaline media, with a HER overpotential of 75 mV and an OER overpotential of 324 mV at 100 mA cm −2 , outperforming commercial Pt/C and RuO 2 . Overall, water splitting requires only 1.68 V at 50 mA cm −2 , indicating low energy consumption. The assembled anion‐exchange‐membrane water electrolyzer (AEMWE) shows remarkable stability, operating over 300 h at 10 mA cm −2 and over 195 h at 50 mA cm −2 at 60°C without significant polarization. These results highlight the synergistic effects of alloy structure, interfacial sites, defect‐rich carbon shell, and 3D conductive network for durable, efficient AEMWE catalysts.