First-principles Study For Reduction Of Graphene Oxide

2004, the research group of A.K. Geim from Manchester University in Englandfirstly manufactured the thinnest material—single layer carbon material (graphene).Graphene holds very special electronic structure properties. For example, the masslesscarriers realize the ballistic transport in graphene, these special properties makegraphene expansive technology prospect in nanoelectronics. Many scientists devotethemselves to the area of graphene based devices, such as graphene based Field EffectTransistor (FET). However, at present, it is hard to make graphene with high qualityand high yield. All of these largely limit the application of graphene in electronicdevices. Among all the graphene manufacture method, reduction of chemicallyderived graphene oxide (GO) is a probable technique for the industrial production ofgraphene. Therefore, this thesis is based on the first-principles calculation method toexplore the feasibility to produce high quality graphene with reduction of GO so thatsome suggestions can be provided for large scale graphene production for electronicindustry.In chapter 1, I will introduce the research history of graphene and the potentialapplication in the electronic industry. At last, I will introduce the problems ofgraphene research in laboratory and the industrial manufacture.In chapter 2, I mainly introduce the basis of first-principles calculation mainlyincluding density function theory (DFT). They explore the system properties thoughelectron density instead of wave function. This method makes it possible to simulatematerial properties based on quantum mechanism. In my thesis, I use first-principlescalculation with VASP code to carry out research.In chapter 3, I analyze the electronic structure for graphene and graphene oxide, which helps us to understand the discipline for the carbon and oxide bond. Oxygenradicals can localize theπelectrons which are originally delocalized in graphene,and also with the increasing of oxygen coverage, the band gap for graphene oxide hasa tendency to increase.In chapter 4, firstly I use first-principles molecular dynamics to simulate thedynamic progress for thermal reduction of graphene oxide. At high temperature, twoadjacent hydroxyls in graphene oxide can form water molecular and can be easilydesorbed from the graphene whereas epoxides radicals are not easily desorbed.However, epoxides can migrate on the graphene. When they encounter, they can formcarboxyl to destroy the integrity of the graphene frame. In fact, pure thermal reductioncan not completely clear the oxygen radicals, so other method to further clear theoxygen radicals has to be designed. For the first time, I use the alkaline-earth metal,such as Ca and Mg, to reduce the graphene oxide. Finally, the remained oxygenradicals can readily be reduced. At the same time, the destroyed graphene mesh is alsorecovered. At last, a suggestion to produce high quality graphene material inexperiment is proposed.