Research On Advanced Nanomaterials Synthesis In Nonaqueous System

Porous materials possess many potential applications in catalysts, sorbents, etc. due to their outstanding characteristics such as high specific surface area, narrow pore size distribution, and high thermal stability. But until now, mesoporous materials'study has been almost confined to oxides and sulfides. Recently, porous silicon nitride materials have attracted much attention because of their potential applications in high temperature solid base catalyst, sensors and so on.In this paper, using surfactants as templates, the precursors were first synthesized through non-oxide sol-gel process in nonaqueous and oxygen–free system, porous silicon nitride based materials with mesoporous channels and high specific surface area were prepared after heat treatment of the obtained precursors, hierachically porous silicon nitride materials with macroporous and mesoporous channels were obtained for the first time by addition of the second surfactant P123. The morphology, structure, surface area, element composition, thermal stability were characterized by advanced means, and the effect of the synthesis conditions such as silicon and nitrogen sources, solvents, surfactants over the morphologies and structures of the products were investigated. The results show that the products with relatively low specific surface area and low thermal stablity were obtained with dimethldichlorosilane as silicon source, the product with high specific surface area and thermal stablity and narrow pore size distribution were obtained with methyltrichlorosilane or silicon tetrachloride as silicon source, respectively. Nitrogen sources also have much influence on the morphologies and structures of the products. To investigate the effect of external condition over the surfactant templates in nonaqueous system, single-crystalline gold nanorods were obtained in nonaqueous microemulsions and gold nanoparticles were obtained in another nonaqueous system by microwave heat treatment, the results show the external conditions such as temperature, time, and stabilizer content have much influence on the obtained products. Self-assembly of surfactants in nonaqueous system can be used to template the synthesis of advanced materials with novel morphologies and structures.