Synthesis of High-Entropy-Alloy Nanocrystals with Controlled Surface Atomic Arrangements for Hydrogen Evolution Reaction

High-entropy-alloy (HEA) nanocrystals have recently attracted significant attention due to their exceptional physicochemical properties. These promising attributes can be attributed to the presence of multiple elements and the four core effects of HEAs. In comparison to random surface atomic structures, shape-controlled HEA nanocrystals exhibit distinct facets and thus surface atomic arrangements, resulting in markedly different properties and applications. However, due to the thermally stable state tending to form a spherical shape, there are no effective strategies reported in the literature for synthesizing shape-controlled HEA nanocrystals thus far. In this study, we provide a straightforward strategy for the synthesis of HEA nanocrystals with controlled surface atomic arrangements and mixing by integrating dropwise synthesis and seed-mediated growth. The synchrotron X-ray absorption spectroscopy (XAS) has confirmed the atomic mixing and coordination environment of HEA nanocrystals with well-defined surface structures. Our work offers a facile and robust strategy to obtain HEA nanocrystals with controlled facets and elucidates the principal growth mechanism in detail. Most importantly, these HEA nanocrystals exhibit significant enhancements in both electrocatalytic activity and durability for the hydrogen evolution reaction in both acidic and alkaline environments, surpassing HEA nanocrystals with random atomic arrangements and commercial Pt/C catalysts. This synthetic strategy can be extended to control the facets of multi-component high-entropy nanocrystals, thereby providing a versatile approach for designing advanced materials with tailored properties for various catalytic reactions.