Abstract:
Since being first synthesized by Brodie in 1987, graphene oxide (GO) has attracted the interest of numerous researchers due to its outstanding chemical, physical and biological properties as well as being a precursor of chemically converted graphene. The applications of the new material have been largely focused on optoelectronic transistors, bio-devices, energy storage devices and polymer nano-composites. In this thesis, new synthesis methods of graphene oxide are characterized using optical microscopy, ultraviolet-visible spectroscopy (UV/Vis),Fourier Transform Infrared Spectroscopy (FTIR), Raman spectroscopy, solid-state 13C NMR, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Although graphene oxide has been utilized and investigated for more than a century, the precise structure of graphene oxide remains unclear and elusive. Structural analysis of graphene oxide has been one of the difficult problems in the field of carbon material sciences. In this study, a series of experiments are used for characterizing the carboxyl groups on graphene oxide. Because the properties of the carboxyl groups on graphene oxide often have a large effect on the acidity, further research is focused on understanding the interactions between alkaline solutions and graphene oxide. The effects of such interactions on the morphology and chemical structure of graphene oxide are probed using optical microscopy, ultraviolet-visible spectroscopy (UV/Vis) and Fourier transform infrared spectroscopy (FTIR) spectroscopy along with traditional titration methods. The mechanism for the de-oxygenation of graphene oxide in alkaline solutions and the location of carboxyl groups on graphene oxide sheets are also discussed. The biological application of graphene oxide is explored in chapter 4. The antibacterial properties of graphene oxide dispersions against E.coli and S.aureus are evaluated. A new mechanism for the interaction between graphene oxide and bacteria is also proposed.