Electrocatalytic oxidation of 5hydroxymethylfurfural (HMF) is considered one of the most environment friendly, economical, and efficient methods for synthesizing 2,5furandicarboxylic acid (FDCA), which is a promising bio-based precursor of polyethylene 2,5-furandicarboxylate . In this study, we synthesized PtRuAgCoNi high-entropy alloy nanoparticles, with an average diameter of approximately 9 nm, using a solvothermal method. The synthesized nanoparticles displayed a core-shell microstructure,

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... n which Co, Ru, Ag, and Ni were distributed over the entire core-shell microstructure of each nanoparticle, while Pt was mainly concentrated in the shell structure. A two-step method, including small-molecule substitution and low-temperature calcination, was used to remove the surfactant from the synthesized nanoparticles without changing the structure and composition of the nanoparticles. After being deposited on a carbon support, the high-entropy alloy nanoparticles, with or without surfactants, exhibited better catalytic performance in the electrocatalytic oxidation of HMF to FDCA than the commercial Pt/C catalyst. The removal of surfactants after calcination at 185 °C can further improve electrocatalytic performance, suggesting promising application prospects of high-entropy alloy nanoparticles in electrocatalysis and green chemistry.