STM Study Of Graphene Nanoribbons And Synthesis And Properties Of Si,SnS₂ Nanometerials

Because of many unique physics and chemical properties different with the ordinary materials, and its potential applications in many fields, nanomaterials received great attentions and were studied widely. There are two parts in this thesis:The first part contain properties of graphene nanometrails, basic concept of scanning tunnelling microscopy (STM) and STM study process of graphene nanoribbons (GRNs) currently. We studied the nanostructure of GNRs using STM and got the scanning tunneling spectroscopy (STS) to certify the existence of edge-state. The disorderd edges were also measured, which came from the hydrogen-plasma etched GNRs. The relationship between the height and the length of the little humps was shown in this thesis, which is a significant result to the research on mechanics property and elastic modulus calculation of GNRs. Besides, the atomic resolution image of the three different edges were gotten and also can be used to certify the edge-state.The second part contain the concept of nonamaterial and its development and application, the principle, application of direct current (DC) arc discharge method and hydrothermal method. we reported our research achievements of nanomaterial (Si and SnS2) synthesis, their growth mechanism, optical and gas sensitivity properties. The contents are as follows:1. One-dimensional Si nanometerials (Si/Sn coaxial nanocable, Si nanowire (SiNW)) were prepared by the DC arc discharge method. The morphology, growth mechanism were analyzed. At argon atmosphere, the Si/Sn coaxial nanocables (Sn-filled Si nanotube (SiNT)) were quickly synthesized with Si powder and Sn powder by the feasible and simple DC arc discharge method. The origin of luminescence is suggested to be the thin silicon oxide layer on the surface of the SiNT and defects in silicon oxide at the SiNT/SiO2 interface. At the same reaction condition, SiNWs were synthesized with Si powder and Ni powder by this facile DC arc discharge method. Compared with these two nanostructures, the catalyst is the key factor to their finial morphology under the similar condition of power and pressure.2. Two-dimensional layered hexagonal SnS2 nanoflakes were synthesized by a mild hydrothermal method. Its morphology, structure and components were characterized in depth. How the reaction temperature, reaction time, predecessor and HCl effect the final morphology of the product were aslo discussed. The selfrepair-epitaxial growth mechanism was suggested to the growth of the SnS2 nanostructures. Gas sensing tests showed that the nanostructures could response to C2H5OH gas, implying its potential application for gas sensors.