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

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 H2‐O2 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. Disordered PtRhPdIrRu high‐entropy alloy nanoparticles (d‐HEA NPs) are synthesized under boiling conditions with the size of 3.5 nm. Compared with well crystallized HEA NPs, d‐HEA NPs displayed a high turnover frequency for hydrogen evolution reaction and stability, outperforming Pt NPs by 5.4 times. In H2‐O2 fuel cells, d‐HEA NPs exhibited a high power density. These results underscore d‐HEA NPs' promise in hydrogen‐related electrochemistry.