Preparation And Application Of Binary Transition Metal Oxide-based Functional Materials

Binary transition metal oxide?BTMO?materials composed of two different divalent or trivalent metal cations have received extensive attention from supercapacitor researchers because of their high electrical conductivity,good bonding and synergistic coupling effects;The homogeneous catalytic oxidation of binary transition metal spinel oxide and peroxymonosulfate?PMS?can effectively degrade organic pollutants in water,which has attracted the interest of many scholars.Based on this,this dissertation prepared a dual-functional BTMO-based nanomaterial that can be used for supercapacitors and the degradation of pollutants in water through a simple one-step method.Small molecule ligands play a dual role of surfactant and linker in the process of hydrothermal/solvothermal preparation of spinel oxides.A variety of physical and chemical characterization methods were used to study the relationship between their morphology,structure,electrochemical performance and catalytic degradation performance.The main contents are as follows:1.One-step preparation of chrysanthemum-like MnCo₂O₄ and study on electrochemical performance and dye degradationIn this work,a bifunctional chrysanthemum-like MnCo₂O₄ was synthesized by simple one-step solvothermal method.We chose the natural short-chain small-molecule ligand-dopamine?DA?instead of the long-chain surfactants traditionally used by people.By exploring the conditions such as the molar ratio,temperature and time between the metal source and the surfactant in the solvothermal reaction,the chrysanthemum-like MnCo₂O₄ modified with dopamine with special catechol structure has a large specific surface area and an open space,so that it becomes an electrode material for supercapacitors and a catalyst that activates PMS to degrade dyes.The electrochemical performance shows that the chrysanthemum-like MnCo₂O₄ we prepared exhibit a high specific capacitance of 843.3 F·g^-1 at a current density of 1A·g^-1,and the capacity is maintained at 75.4%after 1000charge-discharge cycles at a high current density of 10A·g^-1.In addition,MnCo₂O₄also acts as a catalyst to activate PMS to degrade four different dyes?methylene blue,methyl blue,malachite green,and rhodamine B?,and the degradation efficiency exceeded 98%in 20 minutes.2.One-step preparation of spherical CuFe₂O₄ and study on electrochemical properties and dye degradationIn this work,dopamine?DA?,an environmentally friendly short-chain surfactant with a special catechol structure,was used to synthesize different crystal structures by adjusting the concentration of the added surfactant.The size of spherical CuFe₂O₄ is controlled by the interaction between metal ions and the catechol structure of the ligand.Electrochemical performance showed that magnetic spherical CuFe₂O₄prepared with 1 mmol·L^-1 surfactant?CF-1?showed high specific capacitance of960.73 F·g^-1 at a current density of 1 A·g^-1.The initial capacitance retention rate was 57.1%after 1000 cycles at a current density of 10 A·g^-1.In addition,the CF-1 is used to activate PMS to achieve rapid and effective degradation of malachite green?MG?pollutants and the degradation efficiency reaches 96%in 20 minutes.3.One-step preparation of MnCo₂O₄@diatomite and study on electrochemical properties and tetracycline degradationIn this work,the MnCo₂O₄@diatomite composite materials were prepared by one-step hydrothermal method.The scanning electron microscope?SEM?,X-ray diffraction?XRD?and X-ray photoelectron spectroscopy?XPS?were used to analyze the morphology,structure and elemental composition of the material.Short-chain tannins act as surfactants,diatomite with unique porous structure as carrier can increase the active site and accelerate the metal ion transfer rate in the electrolyte,thereby improving the electrochemical performance of the material.The results showed that the specific capacitance of the composite material with diatomite loading of 200 mg?MC@D-200?is 1325.8 F·g^-1 at a current density of 1A·g^-1.In addition,we used it to activate PMS to degrade tetracycline and the degradation efficiency exceeded 92%in 20 minutes.High-performance test results showed that low-cost MnCo₂O₄@diatomite composites are both promising electrode materials for supercapacitors and effective catalysts for degradation of antibiotic drugs in water.