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Very dilute solution of mesoporous silica nano new surfactant synthesis and action of non- lamellar phase nanosized mesoporous cobalt oxide synthesis

Author: ChengHongYun
Tutor: ChenBaoHua
School: Lanzhou University
Course: Applied Chemistry
Keywords: Nano-size Mesoporous silica Aluminum -modified silica Cobalt tetroxide Cathode material Non- layered structure
CLC: TB383.1
Type: Master's thesis
Year: 2009
Downloads: 224
Quote: 1
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Abstract


Nano-sized mesoporous silica and aluminum-modified silica materials with special structural advantages, including high surface area, pore structure and ordered at the nanoscale precision controllable mesoscopic conformation and structure parameters. The mesoporous materials in heterogeneous catalysis, biological fixation, adsorption separation and inorganic functional materials with wide applications in many fields. Cobalt oxide materials is an important anti-ferromagnetic P-type semiconductor material, can be widely applied to electronic devices, sensors, magnetic heterostructures, catalysts and fuel. People use cobalt oxide nano-materials for lithium ion battery anode material, in the charge / discharge cycle, Co 3 O 4 nano-materials showed higher charge capacity. However, compared to silicon-based mesoporous materials to cobalt oxide material as the representative of a transition metal oxide, and its precursor hydrolysis and condensation reactions are generally more intense, soft template synthesis through mostly layered structure of the sample, and the pore structure of the calcination process easy to collapse, resulting in small specific surface area, pore volume is small, the inconvenience to the application. This paper presents a very dilute concentration of reactants in the synthesis conditions mesoporous silica nano-and aluminum-doped silica methods, and soft template hydrothermal synthesis nanosized mesoporous cobalt oxide method. Including the following: 1 in a very dilute solution, by changing the reaction solvent, the amount of deionized water was added to the raw materials or the amount of the aluminum source, controlled synthesis of different size (20 nm ~ 70 nm), morphology and pore structure mesoporous silica nano-particles and nano-aluminum-doped mesoporous silica materials. This material has a high surface area (BET surface area of ??1000 m 2 / g) and large pore volume (1.1 ~ 1.8 cm 3 / g). Reactant or reactants concentration decreased the aluminum source is added after the ordered mesoporous materials decreased, the particle size decreases, the pore volume increases, and produce large amounts of clearance holes. (2) by using a smaller volume of synthetic packing parameter g surface active agent, to obtain non-layered structure of the surfactant micelles, in order to achieve access to non-lamellar mesostructured cobalt tetroxide purpose. We synthesized the n-octadecyl-N-iminodiacetic acid (SHIDA) and n-dodecyl acyl-N-(dimethylaminoethyl dicarboxyethyl)-N-(carboxy-methyl-amino ethyl) amine (TCA) two types of surfactants and sodium laurate, respectively, SHIDA and TCA (volume packing parameter decreases) as the template synthesis of cobalt oxide mesoporous material. TCA as a template to synthesize a non-layered nanosized mesoporous Co 3 O 4 particles, and the experimental conditions were explored. These results once again demonstrate Israelachvili proposed molecular packing parameter determines the mesoscopic structure theory. Finally, the control sintered cobalt oxide nano-particles of mesoporous applied as cathode materials for lithium ion batteries. The results show that this control sintered cobalt oxide cathode materials for first place with a large capacitance to meet the lithium battery cathode materials require low voltage. However, its cycle performance is not ideal, so the cobalt tetroxide sample experimental conditions need to be further optimized.

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