Research On Preparation And Properties Of Metal Oxide/Carbon Composite

Since fullerenes and carbon nanotubes were found, carbon materials is becoming an attractive research field due to its unique applications, such as good electrical and thermal properties, can be used in lithium ion battery, as catalyst supports and other fields. In particular, the spherically shaped carbon materials stand out for its excellent properties. Chemical vapor deposition, templating and other methods that preparation of carbon microspheres need high temperature and synthesis of appropriate template, resulting in more complicated process, higher energy consumption and less surface functional groups of the product. Therefore, two key factors for synthesis of carbon materials are reducing environmental pollution and the cost of the experiment. A process, termed hydrothermal carbonization (HTC), appears especially important contribute to the low cost, renewable resource, simplicity facility, economic and environmental procedure, and has generated widespread interest recently. Meanwhile, SnO2/C composite was synthesized by hydrothermal method from cellulose, electeochemical performance of carbon spheres obtained by hyrothermal carbonization and SnO2/C composite were investigated, respectively.1. The production of carbon spheres by hydrothermal carbonization of cellulose. In this work, using deionized water as a dispersant agent, carbon microspheres were synthesized by hydrothermal carbonization of renewable green resources cellulose. The effects of various reaction parameters on superficial morphology, crystalline in structure and surface functional groups were evaluated, including carbonization temperature, reaction time and pH value. Meanwhile, the carbonization mechanism of cellulose was investigated. The result suggest the onset of hydrothermal reaction occurred at around230℃, and with temperature increasing, the product gradually formed amorphous carbon material; reaction time has little effect on the structure of the product, but on its dispersion; pH value had a great influence on appearance. The obtained carbon microspheres were smooth and monodisperse with particle size of about5～7μm; The surface functional groups of carbons were mainly hydroxyl, carbonyl and other hydrophilic groups, it was easy to modify and introduce some new groups on the prepared carbon microsphere.2. The preparation of SnO2/C composite. On this basis, in order to improve its electrochemical performance, use cellulose as the carbon source, adding a certain percentage of the tin elemental, the spherical SnO2/C composite material was synthesized by means of hydrothermal carbonization. The morphologies, surface microstructures and the electrochemical properties of product was characterized by kinds of test methods. The results showed that, the two products have good thermal stability; and compared with the sample of cellulose carbonization, the electrochemical properties of SnO2/C composite improved significantly, it had good cycle performance and capacitance characteristic as electrode material, and the electronic transmission capacity also clearly increased.