Preparation, Characterization, And Application Of Three-Dimensional Ordered Macroporous Materials

Recently,three-dimensional ordered macroporous (3DOM) materials have been a hot research topic. 3DOM materials not only have the properties of ordinary porous materials, such as high surface area and porosity, but have a series of self-characters of uniform pore size which can be adjusted easily, narrow distribution and periodical structure. 3DOM materials have displayed wide and potential applications in the fields of photonic crystals, separation and adsorption, catalysts and supports, sensors, and electrode materials, etc. So far, colloidal crystal templating method is the main method to prepare 3DOM materials. In this paper, many kinds of 3DOM materials were prepared by colloidal crystal templating process on the basis of reviewing many literatures. And then, 3DOM carbon materials were chosen as supports to upload other activated materials as catalysts or electrode materials.Monodisperse polystyrene (PS) spheres were prepared by emulsifier-free polymerization technology. Through changing the quantity of initiator, the diameter of obtained PS spheres was 270nm, 300nm, 350nm, 480nm, and 700nm, respectively. Another polymer spheres of Poly(methyl methacrylate) (PMMA) with 360 nm was also prepared. Besides polymer spheres, silica spheres with 190nm, 300nm, and 550nm were prepared by traditional St(o|¨)ber method. The prepared spheres were assembly to colloidal crystal templates by the methods of gravitational sedimentation, centrifugal sedimentation, and vertical sedimentation. After assembly, the colloidal crystal templates displayed beautiful colors in sunlight, which was the result of Bragg diffraction. Through the observation of SEM images, the spheres arrayed as face centered cubic structure (fcc) structure.Various metal alkoxides were used as precursors to infiltrate the PS templates, and 3DOM ZrO₂, SiO₂, and TiO₂ materials were successfully prepared. The cheap nitrates were used as precursor at the existence of citric acid, and 3DOM CeO₂, NiO, and Al2O3 materials were prepared. In addition, the solutions of manganese nitrate and zirconium oxychloride were directly used as precursor to infill the templates, and 3DOM MnO₂ and ZrO₂ materials were prepared. 3DOM materials can be looked as the inverse replica of colloidal crystal templates. The macropores were connected through small windows and formed three dimensional networks. Compared with metal alkoxides, metal salts used as precursors are in favor of decreasing costs.Besides 3DOM oxides, 3DOM carbon materials were also prepared by colloidal crystal templating process. Sucrose solutions with concentration of 10%, 20%, and 30% were prepared to be used as precursors, and then infiltrated the silica templates via soaking process. The concentration of precursor had important effects to final structure. When the concentration of precursor was 30%, amorphous 3DOM carbon materials were prepared and had a higher intensity and surface area. 3DOM carbon was used as twice template and zirconium oxychloride solution was infiltrated in it. After calcinations in air, 3DOM ZrO₂ materials with smaller shrinkage were obtained. On the other hand, benzene vapor was used as carbon source to infiltrate the silica template through CVD method, and carbon spheres with 3DOM structure were prepared. Due to the difference of carbon source, carbon spheres obtained from CVD process had obvious graphite property and lower surface area.3DOM carbon materials from sucrose precursor were used as catalyst support. Combining sol-gel technique with soaking process, 3DOM TiO₂/C composites were prepared successfully. Sols of TiO₂ with concentrations of 0.4 mol/l, 0.8 mol/l, and 1.2 mol/l from Ti(OBu)4 were prepared, then 3DOM carbon materials were soaked in sols with different concentration, respectively. After solidification and calcinations, 3DOM TiO₂/C composites with anatase were obtained, which could be looked as a new-type photocatalyst. 3DOM TiO₂/C composites displayed well catalytic ability and regenerated ability when they were used to decompose methyl orange solution which was as the organic waste-water.In the application of electrode materials, the other 3DOM composites of polyaniline/C were prepared by electrideposited method. Aniline was electropolymerized on 3DOM carbon surface by different scan rates of 1mv/s, 5mv/s, and 50mv/s. The composites had EDLC capacitance from 3DOM carbon and faradic capacitance from polyaniline. The specific capacitances of the composites are higher than that of pure 3DOM carbon. 3DOM polyaniline/C composite is an very promising candidate material of supercapacitance.