Ultralow noble-metal-loaded senary high entropy alloy enables industrial-level alkaline hydrogen evolution

The development of cost-effective, high-performance alkaline hydrogen evolution reaction (HER) catalysts is critical for advancing green hydrogen production. Although noble-metal-based high-entropy alloys (HEAs) show promise, their intrinsic activity and scalability remain constrained by particle size, elemental synergy, and scalable synthesis methods. Here, we present a general, facile and scalable impregnation method to synthesize quaternary medium-entropy alloys (MEAs) as well as quinary and senary high-entropy alloys (HEAs). The gram-scale production of high-performance senary HEA is first reported. The average size is less than 2.0 nm. It only required overpotentials of 4.9/149.3 mV to achieve current densities of 10/1000 mA·cm^–2 with an ultralow noble metal loading of 0.12 mg·cm^–2. Its Pt mass activity at –10 mV overpotential is 0.652 A·mg^–1, 13.4-fold higher than commercial Pt/C. Remarkably, it endures over 100 h at 1 A·cm^–² with negligible degradation. Systematic spectroscopic investigations indicate the importance of an optimal electronic modulation via appropriate alloying to enhance the catalytic activity. Density functional theory (DFT) calculations reveal that optimized synergistic interactions among multi-principal elements reduce the hydrogen-adsorption free energy, enhancing intrinsic HER activity. This work not only establishes a scalable pathway for synthesizing high-performance HEAs but also provides new mechanistic insights into electronic-modulating strategy, opening a new avenue to cost-efficient, industrially viable electrocatalysts for green hydrogen production.