Studies on Formation Mechanism of Carbons Hollow Spheres and the Syntheses of Mesoporous Carbon by Using MgO as Cast

• Main Authors: Che-Wei Liu, 劉哲維
• Other Authors: Hong-Ping Lin
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/00985926567633050065

碩士 === 國立成功大學 === 化學系碩博士班 === 95 === Mesoporous carbons of high surface area, large pore volume, high thermal stability and good electric conduction have attracted much attention of chemists and material scientists. Distinct from the typical nano-casting method including complicated and time-consuming synthetic steps, we proposed a new synthetic method by using PF containing polymer blends as template of porous silicas. After a fast sol-el reaction in the acidified silicate aqueous solution, we found the PF-PEO-silica composite in hollow sphere were prepared. The mesoporous carbon hollow spheres can be obtained from high-temperature pyrolysis and HF-etching and the mesoporous silica hollow spheres can be synthesized by calcination in air. In addition to the synthesis of the mesoporous silica and carbon hollow spheres, we also studied the effects of several experimental factor on the physical properties of the mesoporous carbons. According to the experimental results, we tried to propose a formation mechanism of the mesoporous carbon hollow spheres from PF-PEO polymer blend. Then, the mechanism provides mush information to help ones to control the diameter and properties of the hollow spheres. Although the polymer blending method is convenient to prepare the mesoporous carbons, the HF-etching process is essentially required to remove the silica framework. However, HF is hazardous to environment and the health of human. Therefore, we tried to use MgO nanoparticles as spacer that could be easily removed by inorganic acids to substitute SiO2. We tried many chemical compositions to find the most appropriate experimental steps and the composites for the synthesis of mesoporous carbons with high surface area and large porosity. To expand the application of the Mesoporous carbons in electrode materials and supercapacitor, the mesoporous carbon must have both high surface area and high electric conductivity. For improving the conductivity of the mesoporous carbon, we added a proper amount of Fe(NO3)3 into the PF-F127-MgO composite. During the pyrolysis, the iron nanoparticle can catalyze the increase the graphite extent of the mesoporous carbons. According to our experiments, the mesoporous carbons of high surface area and graphite content have been synthesized with a well control on the synthetic compositions.