Theoretical Study On Gas Sensing Properties Of Functionalized Graphene

Graphene is a new carbon-based material and first made successfully in the laboratory by Andre Geim and Konstantin Novoselov in the University of Manchester, UK in 2004. Because of its outstanding mechanical, thermal and electrical properties, it quickly became the research focus in the field of materials science and condensed matter physics in recent years. Many experiment and theory studies indicated that graphene is a good candidate for usage as gas sensor materials to detect various molecules. In order to exploit the potential applications of graphene as gas sensors, the adsorptions of a series of small gas molecules (such as CO,H2O,NO,NO2 and O2) on pristine graphene (PG) and Si-doped graphene (SiG) have been investigated by ab initio calculations. Our results indicate that the electronic properties of PG are sensitive to NO,NO2 and O2 molecules, but not changed much by the adsorption of CO and H2O molecules. Compared with PG, SiG is much more reactive in the adsorption of CO,H2O,NO,NO2 and O2. The strong interactions between SiG and the adsorbed molecules induce dramatic changes to the electronic properties and electrical conductance of SiG. Therefore, we suggest that SiG could be a good gas sensor for CO,H2O,NO,NO2 and O2In this thesis, the density functional calculations were performed to investigate the atomic and electronic structures of Graphene and Si-doped Graphene adsorbed with gas molecules. The theoretical fundamentals, which were used in our research work, were introduced in the first part. The main work done during my master's study is introduced in second part. Introductions as follows:1. Theoretical basis used in researchesIn the second chapter of this thesis, the basic principles for density functional theory (DFT) were introduced. DFT based on first principles methods is a more important method, which can be used to investigate the structure, mechanical, electronic, magnetic and optical properties of small systems, without depending on any empirical parameters. In the third chapter of the thesis, we introduced the structures, the properties and the applications of pristine graphene.2. Theoretical study of graphene and Si-doped grapheneIn the fourth chapter and the fifth chapter, we investigated the atomic and electronic structures of pristine graphene and Si-doped graphene adsorbed with gas molecules, respectively. We found that Si-doped graphene have significantly changed the electronic structures of graphene and improved the gas sensoring to gas molecules.