Defect-rich FeCoNiPB/(FeCoNi)3O4-x high-entropy composite nanoparticles for oxygen evolution reaction: Impact of surface activation

Abstract The high-entropy materials have attracted rising attention for electrolysis application, which may have unusual performances due to the proximal configuration of dissimilar atoms. Meanwhile, design of nanostructure and fine-tuning of crystal structure could further improve their properties. In this work, amorphous FeCoNiPB high-entropy alloy (HEA) ribbons are prepared first, whose superficial species are conversed to FeCoNiPB/(FeCoNi)3O4-x composite nanoparticles with a diameter of ~15 nm by the air after acid etching treatment. It is found that the obtained composite nanoparticles deposited on the surface of FeCoNiPB HEA ribbon with 3D porous array. Besides, the (FeCoNi)3O4-x crystal that derived from amorphous HEA has rich defect structure, including lattice distortions, vacancy defects and discontinuous crystalline fringes. Hence, due to the advantages of heterogeneous nanostructure and defect activation, the FeCoNiPB/(FeCoNi)3O4-x nanoparticle modified HEA ribbon has a high catalytic activity for oxygen evolution reaction, which need low overpotentials of 229 mV and 406 mV to export 10 and 100 mA cm−2 current density with a good stability.