Deciphering Mechanism of Cocktail Effect in High‐Entropy Alloy Catalysis

With cocktail effect from the special synergism of multiple components, high-entropy alloys (HEAs) catalysts are increasingly being investigated to address the sluggish kinetics of electrochemical conversion processes. However, the origin of the cocktail effect and how it affects the catalytic performance is elusive and poorly understood due to complicated interaction between each component. Herein, we decouple the cocktail effect into lattice and coordination two main aspects in HEAs for HER catalysis. Flexible quantum theoretical methods coupled with in situ spectra investigations disclose that the lattice effect contributes to a coarse modulation with a larger tuning range through modification of 3d band structures in active sites, while coordination effect functions as a fine tailor to further optimize electronic structure by adjusting electron occupancy in 3d bands. This work elucidates the intrinsic origin of the cocktail effect in HEAs, providing a guideline for the rational design of catalysts targeting extraordinary properties.