Study On The Strctures And Catalytic Activities Of Low-Dimensional Carbon And Silicon Nanomaterials

Low dimensional nanomaterials have exceptional physical and chemical properties which render them very promising candidates for many applications including energy storage and conversion, environmental monitoring, catalysis, sensors, medicine, electronics and optics. The combination of experiments and first-principles calculations has become the hotspot in the research of nanomaterials nowadays. Recently, the two-dimensional graphene has been regarded as a rapidly rising star because of extremely high specific surface area, outstanding thermal and electrical conductivity, good electro-catalytic activity, superior charge carrier mobility, excellent mechanical strength and high optical transmittance. The modification or functionalization of graphene can sharply improve its properties and broaden its applications. Silicon nanotube, whose element belongs to same group (group IVA) as carbon in the Periodic Table, is a novel one-dimensional nanomaterial after carbon nanotube, and has been promising in the fields of electronic nanodevices. In this paper, on one hand, the graphene oxide and pyridine alkyne functionalized graphene were prepared and characterized. Their catalytic activity was also evaluated. On the other hand, the density functional theory calucations were performed to study the possibly existing coronal silicon nanotubes. The main works are presented as follows:(1) The graphene oxide formed by the Hummers method undergoes washing and centrifugation. The analysis results of XRD and FTIR showed that the distance between layers increased, and the surface of graphene oxide was covered by hydroxyl, carboxylic and epoxy groups, resulting in good hydrophily. The dehydration of benzyl alcohol to dibenzyl ether catalyzed by the obtained graphene oxide was also investigated in terms of the dosage of raw materials, reaction time and temperatures. The results showed that the yield reached85.4%at a higher selectivity.(2) Different functional groups substituted pyridyl alkynyl was synthesized, and then was coupled with the surface of graphene. The resulted nanocomposites were characterized and demonstrated the successful introduction of pyridine on graphene. The test reaction, oxygen reduction reaction (ORR), suggested that the OOR was largely enhanced by the functionalized graphene compared to the unmodified graphene.(3) Four coronal multi-walled silicon nanotubes (MWSiNTs) were identified via first-principles density functional theory calucations and molecular dynamics simulations. It was found that they exhibited high stability and good elastic properties with small Young’s modulus. They also presented metallic characteristics, in striking contrast to bulk silicon and carbon nanotube-like SiNTs. Our study may pay an effective way to explain the structures of MWSiNTs and thereby suggested the possibility of coronal MWSiNTs by the appropriate synthetical choice.