Scalable synthesis and tensile-strain modulation of NiPt_1 % alloy with enhanced large-current hydrogen evolution

Integrating strain engineering into the design and fabrication of large-area electrodes with highly efficient alkaline hydrogen evolution reaction (HER) performance is still a big challenge. Herein, a 6-meter-long CuNi/NiPt_{1 %} alloy cathode with excellent performance has been synthesized through epitaxial growth on the surface of microcone array using our self-developed roll-to-roll electrodeposition system. It delivers ultralow overpotentials of 58.2 ± 4.5 and 158.2 ± 11.2 mV at 100 and 1000 mA cm⁻², respectively, with a low Tafel slope of 28.5 mV dec⁻¹ and an ultra-high mass activity of 64.7 mA μg_Pt⁻¹ @ 100 mV. It maintains 99 % activity retention after 2000-h operation at 1 A cm⁻² and withstands harsh industrial conditions including high-frequency fluctuating load (20–120 %, 1/20 Hz, 100 h) and ultrasonic cavitation (40 kHz, 300 W, 1 h). Multi-scale characterizations reveal that a 2.5 % tensile strain is induced by 50 nm-thick NiPt_{1 %} alloy layers epitaxially grown on the CuNi alloy cone array. This tensile strain enhances the Volmer-Tafel kinetics by reducing activation energy by 26 % and increases surface *H coverage by 4.2-fold. DFT calculations further confirm it enables the transformation of non-spontaneous water dissociation into a spontaneous process, reducing the reaction's energy barrier by 30 %. Additionally, *H adsorption across all surface sites of NiPt_{1 %} alloy is greatly enhanced, resulting in a reduction of 20 % in energy barrier for Tafel reaction. This work proposes a simple and scalable strategy for integrating strain engineering into alloy cathodes with excellent alkaline HER performance.