Sputtered ternary NiMoCu electrodes enabling 70 % energy efficiency for overall alkaline hydrogen production under...

Developing cost-effective and durable electrocatalysts capable of sustaining industrially relevant current densities is essential for large-scale green hydrogen (H₂) production. Here, we report a ternary NiMoCu thin film cathode fabricated via radio-frequency (RF) magnetron sputtering, which ensures strong adhesion between the catalyst layer and the substrate, enabling stable operation at high current densities. The uniform thin-film architecture suppresses catalyst degradation, thereby enhancing long-term durability. Partial oxidation during RF deposition generates oxygen vacancies (V_O), which promote hydrogen intermediates (H*) adsorption and accelerate the Heyrovsky step of the hydrogen evolution reaction (HER). The NiMoCu electrode delivers outstanding performance, achieving 1000 mA/cm² at an overpotential of 432 mV, significantly outperforming NiMo, NiCu, MoCu, and sputtered Pt under identical conditions. Coupled with a previously developed NiFeV anode, the NiFeV(+)‖NiMoCu(-) electrolyzer attains 1000 mA/cm² at 1.92 V, with energy efficiencies of 70.5 % at 500 mA/cm² and 65.3 % at 1000 mA/cm². The system achieves an energy consumption of 44.1 kWh/kg H₂, approaching the 42 kWh/kg H₂ benchmark set by the International Renewable Energy Agency (IRENA) for 2050 targets. This study highlights the promise of RF-sputtered Ni-based ternary thin films as robust and efficient cathodes for practical water electrolysis applications.