Self-magnetic-attracted NixFe(1-x)@NixFe(1-x)O nanoparticles on nickel foam as highly active and stable electrocatalysts towards alkaline oxygen evolution reaction

A facile self-magnetic-attracted approach was developed for highly active and stable NixFe(1-x)@NixFe(1-x)O/NF electrocatalysts towards alkaline oxygen evolution reaction.Firstly,a low-cost and scalable synthesis method was developed to synthesis 4-5 nm hydrophilic NixFe(1-x)@NixFe(1-x)O core-shell nanocrystals with superparamagnetism.Then,these NixFe(1-x)@NixFe(1-x)O nanoparticles(NPs)could be easily supported on nickel foam without any binders or additives.Optimized by the composition effect,the Ni0.7Fe0.3@Ni0.7Fe0.3O/NF exhibits excellent activity for oxygen evolution reaction(OER),requires only 215 mV at 10 mA·cm^-2 and 260 mV at 100 mA-cm-2,with a Tafel slope of 47.4 mV·dec^-1 in 1.0 M KOH.Moreover,the underlying mechanism was carefully studied by X-ray diffraction(XRD),Raman,X-ray photoelectron spectroscopy(XPS)and X-ray absorption near-edge spectra(XANES)analysis and density functional theory(DFT)calculations.Due to the self-magnetic attraction,the catalyst shows outstanding stability throughout the electrocatalysis,surpassing than most self-supported catalysts.This work provides a new strategy for the construction of highly active and stable OER electrocatalysts,the nearly monodisperse magnetic NixFe(1-x)@NixFe(1-x)O NPs also serve an ideal building block for fundamental research of nickel-iron based catalyst.