Synthesis of High-Entropy-Alloy Nanoparticles by a Step-Alloying Strategy as a Superior Multifunctional...

High-entropy-alloy nanoparticles (HEA-NPs) have attracted great attention because of their unique complex compositions and tailorable properties. Further expanding the compositional space is of great significance for enriching the material library. Here, a step-alloying strategy is developed to synthesis HEA-NPs containing a range of strongly repellent elements (e.g., Bi-W) by using the rich-Pt cores formed during the first liquid phase reaction as the seed of the second thermal diffusion. Remarkably, the representative HEA-NPs-(14) with up to 14 elements exhibits extremely excellent multifunctional electrocatalytic performance for pH-universal hydrogen evolution reaction (HER), alkaline methanol oxidation reaction (MOR), and oxygen reduction reaction (ORR). Briefly, HEA-NPs-(14) only requires the ultralow overpotentials of 11 and 18 mV to deliver 10 mA cm^-2 and exhibits ultralong durability for 400 and 264 h under 100 mA cm^-2 in 0.5 m H₂ SO₄ and 1 m KOH, respectively, which surpasses most advanced pH-universal HER catalysts. Moreover, HEA-NPs-(14) also exhibits an impressive peak current density of 12.6 A mg^-1 _Pt in 1 m KOH + 1 m MeOH and a half-wave potential of 0.86 V (vs RHE.) in 0.1 m KOH. The work further expands the spectrum of possible metal alloys, which is important for the broad compositional space and future data-driven material discovery.