Synthesis of FeCoNiCuPt high-entropy alloy nanoparticle electrocatalysts with various Pt contents by a solid-state reaction method

FeCoNiCuPt high-entropy alloy nanoparticles with small sizes (3–7 nm) and different Pt contents have been successfully synthesized by a facile solid-state reaction method. The exposed surface absorption or oxidation of Fe, Co, Ni, and Cu elements; the centered diffraction angles of a single solid solution phase; and the uniform element distributions in nanoparticles illustrate the high-entropy characteristic of nanoparticles. The lattice parameters and grain sizes of nanoparticles are increased by increasing the Pt content from 10% to 30%. The Cdl and ESCA of FeCoNiCuPt nanoparticles are higher than that of commercial Pt/C when the Pt contents are 20% and 30%. The maximum HER/MOR activities and long-term stability of FeCoNiCuPt nanoparticles are achieved when the Pt content is 20%. DFT calculations reveal that the biggest d-orbital overlap bandwidth and the strongest coordinate effects of each element in FeCoNiCuPt nanoparticles are obtained when the Pt content is 20%, which leads to the enhancement of electrocatalytic properties. Thus, this work provides a feasible strategy for synthesizing Pt-based high-entropy alloy nanoparticle electrocatalysts.