Study On Construction Of Fe-Co-Ni Based Nanoarrays And Their Electrochemical Properties

Nanoarrays is one kind of nanostructure that have adhesion to the substrate.Their adjustable structure makes them good candidates for electrode materials and have been widely used in supercapacitors,electrolytic water catalysts and sensors,etc.In our work,transition mental nanoarrays were prepared by hydrothermal method and used as electrode materials,and the electrochemical properties of electrodes are improved by adjusting solvent composition,active material composition and hydrothermal time.The main contents of the study are as follows:1.Porous mesh-like FeCo₂S₄ nanosheet arrays on Ni foam(NF)were prepared by a two-step hydrothermal approach and employed as electrodes for supercapacitors and efficient bifunctional electrocatalysts for water splitting.FeCo₂S₄/NF exhibits ultrahigh areal capacitance of 7.37 F cm^-2 at current density of 5 m A cm^-2.Symmetric solid-state device of FeCo₂S₄/NF as positive and negative electrodes delivers a remarkable energy density of 19.12 W h kg^-1(434.61 W kg^-1).Furthermore,FeCo₂S₄/NF electrode delivers a low overpotential of 155 m V at a HER current density of 10 m A cm^-2.While a low overpotential of 234 m V at 50 m A cm^-2 for OER can be demonstrated in alkaline environment as an anode electrocatalyst.FeCo₂S₄/NF shows excellent activity toward overall water splitting with 10 m A cm^-2by applying just 1.405 V across the two electrodes.2.Fe-Co-Ni sulfide nanoarrays are directly grown on Ni foam by hydrothermal method.The structure and morphology of Fe-Co-Ni sulfide nanoarrays synthesized in different proportion of water to isopropanol and hydrothermal time are analyzed.Fe-Co-Ni sulfide nanoarrays electrode prepared in different conditions are electrochemically tested with a three-electrode system.The test results show that when the rate of water to isopropanol is 1:1 with hydrothermal time of 17 h,the prepared Fe-Co-Ni mesh nanowire sulfide shows the best electrochemical performance.Fe-Co-Ni sulfide exhibits areal capacitance of 3.87 F cm^-2at current density of 5 m A cm^-2 and achieves good cycling stability retaining 89%after 3000recycles.3.Ni_0.5Co_0.5(OH)₂ nanosheet arrays are deposited on Fe-Co-Ni-S nanowires by electrodeposition method.Secondary structure and morphology synthesized in different electrodeposition time are analyzed.Multilayer nanoarrays with different electrodeposition time are electrochemically tested.The result shows that nanowire@nanosheet arrays with electrodeposition time of 90s have best areal capacitance and the stability of this electrode is not excessively reduced compared to the primary structure.The experimental results indicate that the preparation of the secondary structure increases the loading of the material without accumulating the active material.This construction of the three-dimensional nanostructure is beneficial to improve the electrochemical performance of the composite.