Study On Synthesization Of Carbon Silicon Composite Nanoparticles With Different Morphology And Catalytic Performance

Mesoporous nanoparticles with center-radial pore channels, especially the particle size less than 200 nm, has potential application in cell imaging, disease diagnosis, drug/gene/protein storage or transmission, separation and multiphase catalyst due to its large open channel, high contact internal surface area and small particle size. Many scientists have successfully synthesized mesoporous silica nanopaticles with center-radial pore channels. Mesoporous silica nanoparticles can be founctioned by organosilane because of its abundant surface hydroxyl, but the organicsilanes are expensive and have low reuse rate and the amorphous silica-based mesoporous materials have poor hydrothermal stability, which limit its application. Carbon materials do not exist the disadvantages mentioned above, and has good physical and chemical stability, electronic properties. Many scientists have successfully synthesized carbon materials with different morphologies, but the synthesization of MCNs with center-radial pore channels and small particle size(<200 nm) is still a challenge.Therefore, this paper is devoted to synthesizing MSCN with different morphologies and structures through adjusting pH of system. This paper mainly discussed from the following three parts:Part 1, Using MSNs with center-radial pore channels as hard template, sucrose or resorcinol or 4- nitrophenol as carbon sources. Sucrose or resorcinol can successfully synthesize MCNs with center-radial pore channels, which particle size less than 200 nm, but using 4-nitrophenol can not. The reason is that 4-nitrophenol experience low degree of condensation during the carbonization because of it contains only one hydroxyl; Using melamine and sucrose as carbon source can successfully synthesize MCNs containing N, but the amount of melamine should be controlled below 5%.Part 2, Using soft-template method, for getting MSCN with different morphologies, controlling hydrolysis condensation rate of TEOS and condensation rate of RF through adjusting pH of system to affect electrostatic interaction between RF or silica anion and surfactant micelle. Adjusting pH to 8 can get MSCN with center-radial pore channels, and then get MCNs and MSNs with center-radial pore channels after posttreatment.Under the condition of pH is equal to 8, the kinds of alkali can not affect the formation of center-radial pore channels, but affect particle size; Only TEAH3 can synthesis MSCN under 200 nm because of stronger hydrogen bonding interaction to limit the growth of the particles.Part 3, the different structures of MCNs and MSNs are treated by sulfonation, using tert-butyl alcohol and m-cresol as a probe reaction. MCNs-B-1-S、MSNs-B-1-S with center-radial pore channels catalyzed the reaction conversion reaching 65% and 58%, respectively, higher than MSNs-S or MCNs-S with other structure and other system catalyst, showing the advantage of the center-radial pore channels.