Mesoporous Single-Crystal High-Entropy Alloy.

Mesoporous high-entropy alloys (HEAs) represent a promising advancement in mesoporous metals, showing great potential for various applications. Their unique multi-metallic uniformity, strong structural features, and high surface-active-site exposure contribute to their practical catalytic ability. The catalytic efficiency of metal nanostructures depends on both their elemental compositions and crystallinity, with single-crystalline structures generally outperforming polycrystalline ones. However, synthesizing single-crystalline HEA nanostructures with defined mesoporosity remains challenging due to the complex fabrication process. This study introduces a block copolymer micelle-assisted soft-chemical strategy to create single-crystalline mesoporous HEAs (SCPHEAs). These structures feature uniformly sized mesopores that permeate the entire structure, maximizing the exposure of HEA active sites, enhancing material utilization, and facilitating efficient mass and charge transport. The optimized SCPHEAs exhibit excellent electrocatalytic performance in methanol oxidation reactions, surpassing polycrystalline mesoporous HEAs, commercial Pt-C, and various recently reported precious metal-based HEAs and conventional alloy electrocatalysts. This superior performance is attributed to a synergistic effect that results from surface charge redistribution among different atomic entities, which enhances the adsorption of methanol and water molecules and mitigates intermediate CO poisoning. Our synthesis method enables the design of a wide range of mesoporous HEAs with controllable morphology and crystallinity tailored for various catalytic applications and beyond.