Preparation And Supercapacitive Properties Of Cobalt-Based Nanomaterials

With the rapid development of social economic,more and more energy is used,especially for the use of non-renewable fossil fuels,which poses huge social and environmental problems.Therefore,more and more attention are paid to the development of new energy storage devices with high power density,high energy density,and excellent cycling performance electrode materials by researchers.Due to its advantages of high power density,high energy density and excellent cycling performance,supercapacitor,as the new type of green energy storage device has been favored by many developers.Based on a simple hydrothermal reaction,Co3O4 nanomaterial with cubic morphological particles was prepared,and on this basis,the Al2O3-doped Co3O4/graphene nanocomposites were synthesized successfully.Meanwhile,NiCo2O4 materials with controlled morphology and their electrochemical properties in the field of supercapacitors are also investigated.The main contents of the thesis are as follows:1?Hydrothermal synthesis of Co3O4 nanomaterials and its electrochemical propertiesCoCl2 · 6H2O was chosen as the cobalt source,PVP as stabilizing agent and surface active agent,and the ammonia water provided the alkaline environment.Under the hydrothermal condition,Co3O4 nanomaterials with cubic particles were synthesized by adjusting the amount of PVP,reaction temperature.The composition.morphology of the samples were characterized by X-ray diffraction(XRD),Scanning electron microscopy(SEM),Transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),thermal gravimetric analysis(TGA).The results showed that the size of C03O4 material with cubic structure is 50 nm.At the same time,the morphology and properties of Co3O4 synthesized in different solvents are explored.Finally,the properties of Co3O4 synthesized under water solvent conditions are better.2.Hydrothermal synthesis of Al2O3-doped Co3O4/graphene nanocomposites and its electrochemical propertiesBased on the previous part of the experiment,Al2O3-doped Co3O4 and Al2O3-doped Co3O4/graphene nanocomposites were obtained by adding Al(NO3)3·9H2O and Al(NO3)3 · 9H2O&grapehene,respectively.The composition and morphology of the products were characterized by XRD,SEM and TEM.The results showed that Al2O3-doped Co3O4 nanoparticles were supported on graphene by a facile combination of hydrothermal and calcination method.The electrochemical properties of Co3O4,Al2O3-doped Co3O4 and Al2O3-doped Co3O4/graphene electrode materials were tested by cyclic voltammetry,constant current charging and discharging in a three-electrode system with 6 M KOH as the electrolyte.The experimental results showed that the specific capacitance of Al2O3-doped Co3O4/graphene were higher than that of Co3O4 and Al2O3-doped Co3O4 at the same current density,and the capacitance value changed slowly with the current densities increased.The combination of materials can improve the stability of products in electrochemical testing while increasing its specific capacitance.3?Hydrothermal synthesis of NiCo2O4 materials with controlled morphology and electrochemical propertiesCo(NO3)2 · 6H2O and Ni(NO3)2 · 6H2O were chosen as cobalt source and nickel source.PVP as stabilizing agent and surface active agent,the ammonia water provided alkaline environment,NiCo2O4 with controlled morphology was synthesized by the combination of hydrothermal and calcination,The composition,morphology of products were characterized by XRD,SEM,TEM,XPS and BET.The effects of different reaction temperatures,the mount of PVP,and different solvent ratios on product composition and morphology were investigated.The electrochemical properties of synthesized NiCo2O4 electrode materials in 6 M KOH electrolyte solution under different solvent conditions were investigated.The properties of NiCo2O4 synthesized under the conditions of reaction temperature is 180?,the mount of PVP is 0.25 g and water solvent are summarized.