Thermodynamically driven metal diffusion strategy for controlled synthesis of high-entropy alloy electrocatalysts.

We report a thermodynamically driven metal diffusion strategy for the controlled synthesis of high-entropy alloy (HEA) nanocrystals using electrospun carbon nanofibers (CNFs) as nanoreactors. This conceptual pathway is resistant to high temperatures and produces a series of medium-entropy alloy (MEA) and HEA nanocrystals supported on CNFs by adjusting the numbers and kinds of elements. The FeCoNiCrMn/CNFs obtained the lowest overpotential of 345 mV at 50 mA cm-2 compared to MEA. The operando electrochemical Raman results indicate that the enhanced electron transfer from low-electronegativity Fe, Ni, Cr and Mn to the orbit of the Co atom makes Co a local negative charge center, leading to the decrease in absorption energy of OH.