Synthesis And Application Of The Oxide And Carbon Mesoporous Materials

Because of its large surface area and pore volume, high thermal stability, topology diversity of structure, and adjustable framework composition, the reseach on ordered mesoporous material is one of the most attractive topics in the world since its discovery in 1992. They could have potential usage in various areas especially as adsorption and separation, ion exchange, catalysis, molecular host, optoelectronic, photo devices, sensing, drug delivery, which have been the focus of the research in the condensed matter physics, chemistry and material fields.Industrial application of mesoporous molecular sieves in catalysis and energe storage is a very challenging and potential research direction, it involves broad scientific knowledge. We focused on the synthesis and applications of functional mesoporous molecular sieves such as Ti-containning SBA-15, mesoporous carbon and mesoporous carbon nitrides. The main contents of our work are summarized as follows:1.Using the same method we attempted in synthesis of Ti-containning SBA-15, a series of highly order titanium dioxide/mesoporous SBA-15 (TiO2/SBA-15) materials with different Si/Ti ratios have been directly synthesized using tetraethyl orthosilicate (TEOS) as silica precursor, tetraethoxytitane (TBOT) as titanium precursor, and EO20PO70EO20 (P123) as structure-directing reagent. The influence of different Si/Ti ratios to the structure and morphology of the Ti-containing SBA-15 materials has been systematically studied by using small-angle x-ray diffraction (SAXRD), wild-angle x-ray diffraction (WAXRD), transmission electron microscopy (TEM), fourier transform infrared (FTIR) spectroscopy, nitrogen adsorption-desorption measurements and Diffuse reflectance UV-vis spectra (DRS). It was observed that a limited content of titanium can be incorporated into the silicate framework of SBA-15 without provoking structure changes. Anatase phase was observed on the external surface of the solid particles at high titanium loadings.2. Ordered mesoporous carbon (OMC) was prepared using mesoporous silica SBA-15 as hard templates. Source could be completely incorporated into the channels of SBA-15 templates. Then, carbonize the carbon precursors at 900℃in the N₂ atmosphere and dissolute the templates by using HF solution at room temperature. OMC materials maintain the macroscopic morphology and ordered mesostructures of the SBA-15 templates. XRD, HRTEM and N₂ adsorption results reveal that the materials are structurally well ordered with a two-dimensional porous structure, a high surface area (1896.95m²g^-1) and a large pore volume (1.781 cm³g^-1). The pore diameter of the OMC materials is about 5.1 nm.3. Ordered mesoporous carbon nitrides were synthesized by using ethylenediamine (EDA) and carbon tetrachloride (CTC) as ceramic precursors and mesoporous silica SBA-15 as a hard template via nanocasting synthesis. Small-angle x-ray scattering, TEM, and nitrogen sorption analyses showed that the mesoporous carbon nitride products have a two-dimensional hexagonal structure (P6mm) similar to SBA-15, a specific BET surface area of 684.932m²g^-1, a large pore volume of 0.701cm³g^-1, and a narrow pore size distribution at the mean value of 5.086nm.4. The electrochemical properties of prussian blue (PB) were greatly improved by order mesoporous carbon (OMC). PB was efficiently deposited on the OMC modified PG electrode. The microstructure and electrochemical behavior of the PG/OMC/PB electrodes were investigated by cyclic voltammetric (CV) route. Compared with the PG/PB electrode, the PG/OMC/PB electrode shows much better electrochemical stability, much wider pH adaptive range and larger response current to the reduction of hydrogen peroxide (H₂O₂).5. The electrochemical hydrogen storage properties of mesoporous carbon nitride and mesoporous carbon were researched. Some OMC or MCN with Nickel powder were mixed together on a certain ratio, to get the cathode material of OMC-Ni or MCN-Ni electrode. The electrochemical hydrogen storage performances of them were studied. The electrochemical hydrogen storage ability of pure Ni was researched and found that it has a neglectable effect on the electrochemical hydrogen storage characteristic of the whole OMC-Ni or MCN-Ni electrode, and it played a roll as cohesion and conduction in the electrode preparation. The content of Ni in the OMC-Ni electrode has a greater impact on hydrogen storage electrode performance. Adding the nickel powder improved the activation performance of electrode. Electrochemical hydrogen storage capacity increases with the amount of nickel powder. The maximum hydrogen storage capacity was 170mAhg^-1, at this time Ni: OMC = 3:2, and then hydrogen storage capacity increased with the nickel powder decreases. The chemical composition of MCN and content of nickel powder added have a greater impact on performance the electrochemical hydrogen storage capacity. Charge-discharge experiment also proves that the discharge capacity increase with the increase of cycle number at beginning. It is shown that the electrochemical hydrogen storage electrode has an activation process. Hydrogen storage capacity reaches a maximum after 8 times charge-discharge circles, and its discharge capacity is 40mAhg^-1.