Plasma-Assisted Fabrication of Defect-Rich Tri-Phase NiRu Alloy/Carbon Shell Heterostructure with Ni-O-Ru Interfaces...

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 RuO₂. 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.