Construction And Electrocatalytic Performance Of NiFe-based Self-supporting Nanocomposites

Low-carbon development is not only an important yardstick to measure the effectiveness of high-quality development,but also an effective means to promote high-quality development.Under the foreseeable technical and economic conditions,in order to realize the vision of carbon neutrality,research and develop clean,efficient and sustainable new energy attracted a lot of attention..Electrochemical water splitting which benifits from the advantages of mild reaction conditions,compact reactor form and the like,and the electric energy for driving the reaction can be provided by unstable energy sources such as solar energy,wind energy,tidal energy,has been recoginized as a promising technology for sustainable hydrogen energy conversion and storage.Finding highly active,durable,and low-cost hydrogen/oxygen evolution reaction（HER/OER）electrocatalysts to replace noble metal-based catalysts is of great significance for large-scale applications in water electrolysis.NiFe-based compounds have attracted increasing attention due to their low cost,high availability,and excellent catalytic performance for hydrogen and oxygen evolution.In this paper,a series of electrocatalysts based on Ni and Fe,were rational constructed,and the effects of the composition,morphology,structure of the materials,and The relationship between microstructure such as particle size and pore size and macro catalytic activity was explored.The details are as follows:1.Self-supported nanomaterials Fe Mn-Ni（OH）₂@MOF/NF consisting of metal organic frameworks（MOF）and hydroxides was constructed by ligand etching the Fe Mn codoped Ni（OH）₂nanosheets grown on nickel foam（NF）.Thanks to the unique hierarchical structure,polymetallic active nodes and two kinds of active materials grown in situ,the prepared Fe Mn-Ni（OH）₂@MOF/NF exhibits excellent OER activity,requires only 199 m V potential to drive a current density of 10 m A cm^-2,and possess excellent stability.This study will provide a new strategy for the design of high-performance OER electrocatalyst.2.A self-supporting electrocatalyst with MOF as a self-sacrificial template for partial conversion to layered double hydroxide（LDH）was constructed on the surface of iron foam（IF）by a hydrothermal reaction combined with a hydrolytic etching strategy.By adjusting the amount of Ni and the reaction time,the NiFe-LDH@Fe-MOF/IF-2 catalyst with the best performance was screened out,and the effect of morphology on the catalytic performance was explored.Benefiting from the unique hierarchical structure with large active area and abundant active sites,the coupling of highly active amorphous NiFe-LDH and Fe-MOF,and the high conductivity and stability of MOF arrays grown in situ on IF,the obtained NiFe-LDH@Fe-MOF/IF-2 exhibits excellent OER activity in alkaline electrolytes,requiring overpotentials of 183,237 and 257 m V to achieve current densities of 10,100 and 200 m A cm^-2,respectively,and maintaining at least 20 hours of long-term stability.This work provides new insights into the design and development of self-supporting MOF-derived high-performance NiFe-based electrocatalysts.3.Ru species were doped into a composite of Fe₃O₄and Fe Ni layered double hydroxides by a one-step oil bath method,and a self-supporting binder-free bifunctional electrocatalyst Ru-Fe₃O₄@Fe Ni-LDH/IF was synthesized on the surface of IF.The unique 3D core-shell nanoflower structure,the combination of active components and conductive substrates,coupled with the doping of Ru,can provide a large number of active sites,adjust the electronic structure,and accelerate electron transfer,thereby greatly improve electrocatalysis activity and durability.It is worth mentioning that when Ru-Fe₃O₄@Fe Ni–LDH/IF was used as the anode and cathode for overall water splitting,only 1.52 V battery voltage can generate a current density of 10 m A cm^-2,and also maintain a prominent stability for at least 36 hours.This work provides a feasible strategy for heteroatom-doped NiFe-based materials as bifunctional electrocatalysts.4.Using amorphous nickel nanosheets to encapsulate NiFe₂O₄nanoparticles on 3D porous IF substrates,an electrocatalyst with unique nano flower structure was successfully constructed.The effects of the introduction of metal Ni and the evolution of catalyst morphology on the electrochemical activity were studied,and the structure-activity relationship between the components,morphology and catalytic properties was further explored.The experimental results demongstrate that the unique nanoflower structure,the synergistic effect of multiple active substances,and the coupling of catalytic materials and conductive substrates can significantly enhance the catalytic performance.The designed Ni-ANS@NiFe₂O₄/IF requires only 209,251,and 270 m V at current densities of 10,100,and200 m A cm^-2,while maintaining remarkable long-term stability at high current densities.This work broadens new horizons and avenues for the design of efficient NiFe-based OER catalysts.