Cu-Mediated Ordering Transition and Size Control of Pt-Based High-Entropy Intermetallic Nanocatalysts for Enhanced Alkaline Hydrogen Evolution

Pt-based high-entropy intermetallic (HEI) nanocatalysts have attracted widespread attention due to their promising catalytic performance. However, synthesis of HEI nanoparticles with fine size and highly ordered structure faces significant challenges. Herein, we employed Cu as a bridging element to successfully synthesize ultra-fine (5.23 nm), highly ordered Pt 4 FeCoNiCu-HEI nanoparticles. The moderate reduction potential of Cu facilitates uniform co-reduction, controlling nanoparticle growth. The low surface energy of Cu promotes its migration to the particle surface during high-temperature annealing, creating lattice vacancies that significantly lower the ordering energy barrier. The resulting nanocatalyst exhibits enhanced alkaline hydrogen evolution reaction (HER) performance, achieving low overpotentials of 15.8 mV and 96.8 mV at current densities of 10 mA cm -2 and 100 mA cm -2 , respectively – approximately half those of commercial Pt/C (36.2 mV and 206.2 mV). The nanocatalyst demonstrates outstanding stability, maintaining its performance after 10,000 CV cycles and 30 hours of chronopotentiometry testing. Density functional theory (DFT) calculations reveal that lattice distortion and multi-element doping synergistically lower the d-band center of Pt active sites, optimizing hydrogen adsorption free energy. Additionally, the transition metal constituents significantly reduce the energy barrier for the water dissociation step. This work presents a novel strategy for designing high-performance HEI nanocatalysts combining small size, high ordering, and optimized electronic structure. Download: Download high-res image (299KB) Download: Download full-size image