Tailoring Crystal Phase of High-Entropy Alloy Nanoparticles via Redox-Mediated Engineering

High-entropy alloys (HEAs) have already shown great promise for a range of emerging applications, particularly in catalysis, yet their development is constrained by an unresolved challenge: the incompatibility between achieving high configurational entropy and precise crystal phase control. Here, we introduced a redox-mediated kinetic engineering strategy that simultaneously fulfilled both criteria by decoupling nucleation and growth processes. Through staged modulation of reduction potentials—first creating kinetic divergence for phase-specific nucleation, then enabling rapid co-reduction for high-entropy products, we achieved HEAs with tailored crystal structures. Distinct hydrogen evolution performance between different crystalline phases of HEAs unequivocally demonstrated the critical role of crystal phase in determining catalytic properties. The developed synthetic paradigm provided a general route to manipulate HEA phases while preserving high entropy, opening new possibilities for tailored materials design in catalysis and beyond.