Rapid Microwave Synthesis of Co–Mn–Ni–Pd–Pt High-Entropy Alloy Nanoparticles with Engineered Twin Boundaries for Alkaline Hydrogen Evolution Reaction

Breaking conventional catalytic scaling relations remains a major challenge in designing efficient electrocatalysts for the hydrogen evolution reaction (HER). Here, we report an ultrafast microwave-assisted strategy for scalable synthesis of nanostructured Co–Mn–Ni–Pd–Pt high-entropy alloy (HEA) electrocatalysts within 5 min. Volumetric microwave heating enables synchronized reduction of multiple metals, producing phase-pure HEA nanoparticles (∼5 nm) with homogeneous elemental distribution. The complex atomic configuration induces significant lattice distortion and hierarchical twinning defects, which may modulate the d-band center and tailor hydrogen intermediate (H*) adsorption energetics. (1−3) The optimized HEA catalyst on functionalized carbon delivers outstanding alkaline HER performance, requiring only 28.7 mV overpotential at –10 mA cm –2, outperforming commercial Pt/C at substantially lower noble-metal loading. The catalyst further demonstrates excellent activity in simulated and natural seawater with long-term stability over 100 h. This work establishes microwave-driven synthesis of defect-engineered HEAs as a rapid, scalable platform for next-generation electrocatalysts.