Formation of Disordered High‐Entropy‐Alloy Nanoparticles for Highly Efficient Hydrogen Electrocatalysis

Abstract Nanoparticles composed of high‐entropy alloys (HEA NPs) exhibit remarkable performance in electrocatalytic processes such as hydrogen evolution and oxidations. In this study, two types of quinary HEA NPs of PtRhPdIrRu, are synthesized, featuring disordered and crystallized nanostructures, both with and without a boiling mixture. The disordered HEA NPs ( d ‐HEA NPs) with a size of 3.5 nm is synthesized under intense boiling conditions, attributed to improved heat and mass transfer during reduction of precursors and particle growth. The disordered HEA NPs displayed an exceptionally high turnover frequency of 33.1 s −1 at an overpotential of 50 mV, surpassing commercial Pt NPs in acidic electrolytes by 5.4 times. Additionally, d ‐HEA NPs exhibited superior stability at a constant electrolyzing current of 50 mA cm −2 compared to commercial Pt NPs. When employed as the anodic catalyst in an H 2 ‐O 2 fuel cell, d ‐HEA NPs demonstrated a remarkable high current power density of 15.3 kW per gram of noble metal. Consequently, these findings highlight the potential of d ‐HEA NPs in electrochemical applications involving hydrogen.