Preparation And Capacitive Performance Of MOF-derived Co₃O₄/NiO/Mn₂O₃

In this paper,Co3O4/NiO/Mn2O3 and Co3O4/NiO/Mn2O3@C composites are prepared by hydrothermal calcination method and mechanical mixing method.The crystal structure and element distribution of the composites are characterized by X-ray powder diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).The microstructure of the composite is observed by scanning electron microscopy(SEM).The specific surface area and pore distribution of the composite are observed by BET method.On the other hand,the cyclic voltammetry(CV),galvanostatic charge-discharge(GCD),and electrochemical impedance spectroscopy(EIS)tests are used to study the capacitive performance of the Co3O4/NiO/Mn2O3 and Co3O4/NiO/Mn2O3@C composites.Cobalt nitrate,nickel nitrate,manganese nitrate,terephthalic acid,N,N-dimethylformamide and absolute ethanol are used as raw materials to synthesize CoNiMn-MOF on a nickel foam substrate by one-step hydrothermal method.Subsequently,by means of temperature-controlled calcination under nitrogen and air conditions,respectively,tremelliform Co3O4/NiO/Mn2O3 is obtained.In the 6 M potassium hydroxide electrolyte,when the current density is 1 mA cm-2,the composite specific capacitance reaches 3652 mF cm-2;even when the current density is increased to 20 mA cm-2,the specific capacitance still reaches 2519 mF cm-2,indicating that the composite has good rate performance.In addition,after 10000 cycles at a current density of 5 mA cm-2,the specific capacitance remains 79.6%of its initial value,indicating that the cycle performance of the composite is well.On the other hand,we have assembled asymmetrical supercapacitors with Co3O4/NiO/Mn2O3 and rGO.It exhibits a power density of 343.4 W kg-1 and an energy density of 65.7 Wh kg-1 at a current density of 2 A g-1.A maximum power density of 3434 W kg-1 is obtained at an energy density of 24.5 Wh kg-1.These excellent electrochemical properties further illustrate that Co3O4/NiO/Mn2O3//rGO is a promising supercapacitor electrode material.Co3O4/NiO/Mn2O3@C is prepared by mechanical synthesis using Co3O4/NiO/Mn2O3 and elm money calcined biomass carbon as raw materials.The experiment successively used orthogonal test and single factor controlled variable analysis method to explore the effect of cobalt oxide/nickel oxide/manganese oxide and biomass carbon mass ratio,grinding time,solvent volume and electrolyte concentration on the capacitive performance of the composite..When the current density is 1 mA cm-2,the specific capacitance of the composite is up to 3159 F g-1,and after 10000 cycles,the specific capacitance maintains 89.8%,indicating that the composite has good cycle performance.