Controllable Synthesis, Magnetism Functionalization And Applications Of Carbon Nanospheres

Carbon spheres play a significant role in many areas of modern science and technology, and they can serve as reinforcement substances for rubber, adsorbents, supports of catalytic systems and media for energy storage, etc. In the practical appellations, the size, structure and morphology of the carbon spheres are directly related to their performance. Therefore, more and more attentions are paid to the controllable synthesis of carbon spheres.This research work mainly covers the following aspects:develop new and simple synthesis methods for monodisperse hollow sphere materials, and study the influence of the synthesis condition on their textural parameters and morphology; introduce magnetic nanoparticles into the carbon spheres and magnetism functionalize the carbon spheres, main study the formation process of the monodisperse magnetic carbon spheres with uniform size; explore their applications in the fields of catalysis and adsorption. The detailed content is presented as follows:1. Polystyrene PS) spheres with different sizes were firstly synthesized using emulsion polymerization. The effect synthesis parameters, such as the kind and amount of surfactant and the amount of monomer, on the size of PS spheres were investigated. Firstly, PS sphere coated by phenol formaldehyde resin (PS@PF) particles were prepared via a hydrothermal approach using phenol and HMT as raw materials, PS sphere as template. The uniform hollow carbon spheres were obtained after silica coating, carbonization of PS@PF@SiO2and removing the silica layer. The obtained hollow carbon spheres were monodisperse due to the protection of silica shell. The size of the hollow core, which depends on that of the PS colloid sphere template used, can be adjusted in a rage of40-300nm. The shell thickness of the hollow carbon spheres can be controlled by varying the PS and phenol formaldehyde resin mass ratio. The corresponding hollow carbon spheres possess excellent structural characteristics including uniform particle size, abundant pores and rather high specific surface area and void volume and so on. The texrural parameters of the carbon spheres can be changed by water activation. The activated hollow carbon spheres show a good adsorption capacity to phenol.2. Fe2O3cube with the size about40nm were fabricated via hydrothermal approach using Fe(NO3)3·9H2O as raw materials, PVP as surfactant and DMF as solvent. Then the monodisperse Fe2O3/phenol formaldehyde resin spheres with core/shell structure (Fe2O3@PF) were synthesized by using the Fe2O3as core, phenol and HMT as raw materials. TEM and FT-IR were employed to investigate the structure and compose of the Fe2O3@PF particles. The effect of synthesis parameters, such as reaction temperature, reaction time and the reactant ratio, on the size of Fe2O3@PF particles was investigated. By adjusting the synthesis condition, uniform Fe2O3@PF particles with well core-shell structure were prepared. The diameter of Fe2O3@PF particles can be changed in the range of50-230nm.3. After coating a silica layer on the Fe2O3@PF particles and subsequent carbonization of the as-made Fe2O3@PF@SiO2and removal of silica layer, the magnetic carbon with different size can be obtained. The magnetic carbon nanoparticles were investigated by SEM, XRD, FT-IR, TG, and nitrogen adsorption techniques. The effects of carbonization temperature on the morphologies, structures and components of the prepared magnetic carbon were studied. The results showed that the pyrolysis temperature play an important role on the morphology and textural structure of the final products. With increasing pyrolysis temperature, the surface became more and more rough. When the pyrolysis temperature increased to800℃, the carbon spheres were translated to graphitic nanostructure. The iron oxide was translated from Fe2O3to Fe3O4and Fe. The saturation magnetization of magnetic carbon sphere was13.7emu/g. Chosing the FexOy@C with a diameter of200nm as support, the prepared Pd/FexOy@C shows a good catalytic oxidation activity of benzyl alcohol. Various materials, such as hollow carbon sphere, hollow silica sphere with a movable magnetic core, could be obtained by different treatment to the intermediate product Fe2O3@PF@SiO2.