Heterogeneous high-entropy catalyst nanoparticles for oxygen evolution reaction: Impact of oxygen and fluorine introduction.

High-entropy catalysts attract rising attention for promoting oxygen evolution reaction (OER) due to the advantages of multiple catalytic active sites, unique lattice distortion effect, interatomic d-band ligand effect, etc. However, it still needs to design new high-entropy catalysts with low cost and high efficiency to meet the requirement of large-scale applications. In this study, AlNiCuCoFeY amorphous alloy ribbon is prepared by melt spinning method. Then, the ribbon is etched in HF solution to form a nanoparticle modified ribbon, whose superficial species are further conversed to high-entropy oxides/Al alloy (HEO/Al alloy) or high-entropy fluorides/Al alloy (HEF/Al alloy) heterogeneous nanoparticles with a diameter of ∼20 nm by subsequent oxidization or fluorination process. Herein, the oxidized metallic elements with high valence state can promote the adsorption of OER. Due to the large surface area, multiple active sites, and the synergistic effect of different species, the HEO/Al alloy or HEF/Al alloy composite only need 293 and 261 mV overpotential to afford 10 mA cm−2 current density. This work discusses the design of high-entropy electrocatalysts and demonstrated a promising route to improve their OER electrocatalytic performance. [Display omitted] • AlNiCuCoFeYO x and AlNiCuCoFeYF x high-entropy catalyst with high efficiency are obtained. • The crucial role of introduction of O and F elements in high-entropy catalyst is discussed. • AlNiCuCoFeYO x and AlNiCuCoFeYF x nanocrystals are mixed with amorphous AlNiCuCoFeY nanocrystal. • HEO/Al alloy and HEF/Al alloy need 293 and 261 mV overpotentials @ 10 mA cm−2 current density. [ABSTRACT FROM AUTHOR]