Multisite Synergism‐Induced Electron Regulation of High‐Entropy Alloy Metallene for Boosting Alkaline Hydrogen Evolution Reaction

Abstract Designing the high‐entropy alloys (HEAs) electrocatalysts with controllable nanostructures is of great significance for the development of efficient alkaline hydrogen evolution reaction (HER) electrocatalysts. In this study, an ultrathin HEA‐PdPtRhIrCu metallene with abundant lattice distortions and defects is prepared via a facile one‐step hydrothermal method. The synthesized HEA‐PdPtRhIrCu metallene exhibits superior HER performance in a 1 m KOH solution, where the required overpotential of HEA‐PdPtRhIrCu metallene is only 15 mV to reach a current density of −10 mA cm −2 while possessing a low Tafel slope for 37 mV dec −1 . Density functional theory calculations further prove that the synergistic effect of the five elements can optimize the electronic structure to enhance the HER activity of the catalysts. In particular, the strong coupling effect and the strong bonding arising from the interaction between the multi‐metal components can facilitate the electron transfer of the surface and high electroactivity. Moreover, the optimized Pt electronic structure in HEA‐PdPtRhIrCu metallene promotes the optimal PtH binding at the Pt site, thus promoting HER performance.