Preparation Of Metal Foam(Ni-Fe?Co?Cu)Derived Composites And Their Electrocatalytic Performance For Oxygen Evolution

As an important cornerstone of the development of industrial revolution,energy plays a key role in the progress of human society.Several industrial revolutions and social development that human beings have experienced are based on the use of fossil fuels.Due to the possibility of fossil fuel depletion,the development of renewable alternative energy has obvious advantages.All over the world,new renewable energy resources are being researched and developed,such as solar energy,wind energy,tidal energy,geothermal energy,etc.Because of the high energy density energy,easy to get raw materials and clean products,hydrogen energy has been regarded as the development strategy and research hotspot for various countries.Electrolytic water splitting is a traditional method for hydrogen production,which can be divided into two semi reactions:cathode hydrogen evolution?HER?and anode oxygen evolution?OER?.The key point is to develop high activity,high stability and low price catalysts for industrial production.Although commercial platinum,ruthenium and iridium are ideal electrocatalysts,their small reserves and high prices restrict the large-scale application.In this study,low cost?iron nickel foam,copper foam and cobalt foam?were used as catalyst supports to prepare porous nickel doped microspheres,cobalt selenide nanosheets,and urchin like cobalt oxide nanowires composite materials.Because of the use of self-supporting materials,the disadvantages of the powder catalyst preparation electrode and the binder easy to cover the catalytic active sites are avoided.The specific research contents are as follows:1. Fe-incorporated Ni Se microspheres?Fe-Ni Se microspheres?were prepared by solvothermal method using iron and nickel foam as nickel source,iron source and carrier,selenium powder as selenium source and anhydrous ethylenediamine as reducing agent.The samples were studied by means of XRD and XPS.indicating that Fe³⁺ions were successfully incorporated into Ni Se lattice.SEM and EDS were used to study the morphology of Ni Se,and the uniform distribution of Ni Se microspheres was observed.The materials with solvothermal reaction temperature of 180?showed the best electrocatalytic oxygen evolution performance.The excellent OER performance is mainly attributed to the synergistic effect of active Fe-Ni Se,the derived Fe-Ni hydroxide and the 3D porous structure of Fe Ni foam.In the porous Fe-Ni Se microsphere,the introduction of Fe atom can not only regulate the electronic structure of nickel selenide,but also change the active site structure of nickel selenide and produce more active site exposure,so as to enhance the electrocatalytic oxygen evolution performance.In addition,through the stability test,the voltage loss at the current density of 50 m A cm^-2 for 24 hours is small,which shows that the composite has good stability.2. Co_0.85Se nanosheets were prepared by solvothermal method using cobalt foam as the cobalt source and carrier,selenium powder as selenium source and anhydrous ethylenediamine as reducing agent.The samples were characterized by means of XRD and XPS,which showed that Co_0.85Se was successfully prepared.The morphology of Co_0.85Se was studied by means of SEM and EDS.The solvothermal reaction temperature of 160?exhibits excellent catalytic activity and stability for oxygen evolution.The good OER performance is mainly attributed to the in-situ growth of Co_0.85Se nanosheets on the cobalt foam with enough active centers and the tight junction of Co_0.85Se nanosheets and three-dimensional porous cobalt foam substrates,thus achieving effective electron and ion transport.In addition,the stability of the composite was tested under the current density of 20 m A cm^-2,and the current loss was small for 10h,which indicated that the composite had good stability.3. With copper foam and cobalt nitrate as the support and cobalt source,respectively,Co₃O₄ was prepared by solvothermal method followed by calcineing at high temperature to obtain the composite material loaded on copper foam.The composition,structure and morphology of the Co₃O₄@Cu were studied by means of XRD,XPS,SEM,and TEM,showing that the urchin like Co₃O₄ nanowires were successfully synthesized on the copper foam.Compared with different calcination temperature samples,the samples obtained at 250?exhibited a good catalytic activity for oxygen evolution,mainly due to the fact that the urchin like nanowires were beneficial to expose more active sites,and the copper foam had good conductivity,which could improve the electron transport properties and improve the catalytic oxygen evolution performance.At the same time,through the stability test,the voltage loss at the current density of 20 m A cm^-2 for 15 hours is small,which shows that the composite also posseses good stability.