Selective Growth Tailors Atomic Arrangements of High-Entropy Alloy and Intermetallic Nanocrystals for Enhanced Catalytic Performance

High Resolution Image Download MS PowerPoint Slide Precise control over atomic arrangements in multicomponent nanocrystals is essential for fully realizing the catalytic potential of high-entropy alloys (HEAs) and high-entropy intermetallics (HEIs). However, achieving anisotropic growth while preserving homogeneous multimetallic mixing remains a major challenge in catalyst design. Here, we present a selective-growth strategy in which CO acts as a facet-selective capping molecule to direct surface atomic configurations in PtCo-based multicomponent systems. Density functional theory (DFT) calculations reveal that CO preferentially stabilizes {100} facets, even on compositionally disordered high-entropy surfaces, thereby enabling directional growth when combined with controlled precursor delivery and seed-mediated nucleation. Experimentally, this strategy produces atomically mixed PtCo@PtCoNiRuRh core–shell cubic HEA nanocrystals and PtCo@PtCoNiCuSn core–shell cubic nanocrystals with partially ordered HEI structures, in which ordered L1 2 domains coexist with disordered A1 regions. Synchrotron X-ray absorption spectroscopy (XAS) confirms heterometallic coordination and homogeneous atomic mixing, in sharp contrast to the phase-segregated structures obtained through conventional one-pot synthesis. The resulting PtCo@PtCoNiRuRh core–shell nanocubes exhibit substantially enhanced hydrogen-evolution activity and durability in both acidic and alkaline electrolytes, which can be attributed to their engineered surface structures and optimized hydrogen and hydroxide binding. This work establishes selective growth as a promising strategy for controlling surface facets in multimetallic nanocrystals for catalysis.