Graphene: Synthesis, characterization, properties and chemical modification

Abstract

The thesis consists of seven chapters of which the first chapter provides a brief overview of graphene. Chapter 2 deals with the synthesis and characterization of graphene. When graphene research was initiated in our laboratory, there was little information available on synthesis and characterization methods. This necessitated exploration of various methods of synthesis. Different synthetic routes namely, exfoliation of graphite oxide, conversion of nanodiamond, chemical vapor deposition and reduction of graphene oxide, including newly discovered arc discharge route and radiation induced reduction of graphene oxide have been described. The samples so obtained have been characterized by utilizing different techniques such as electron microscopy, Raman spectroscopy and atomic force microscopy. Chapter 3 describes different ways of functionalizing graphene. Amidation and reaction with organo silane or tin solubilize graphene in organic solvents whereas wrapping with surfactants gives water soluble graphene. Noncovalent π-π interaction with a pyrene derivative solubilizes graphene in dimethylformamide. Chapter 4 presents some properties of few-layer graphenes and comprises six parts. Part 1 deals with the surface properties and uptake of H2, CO2 and CH4 by graphene. Part 2 and 3 presents magnetic and electrochemical properties of graphene respectively. Magnetic properties of different graphene samples have been investigated and magnetism in graphene could be tuned by adsorption of certain specific molecules. Electron transfer kinetics of different graphenes and their use as electrode material in supercapacitors have been investigated. Part 4 deals with emission properties of graphene based materials and part 5 gives patterning and lithography based on graphene. x In Chapter 5, investigations on interaction of graphene with electron donor and acceptor molecules and different metal nanoparticles have been presented. The G, D and 2D bands in the Raman spectra of graphene have been employed to examine the interaction of electron donor and acceptor molecules as well as of different metal nanoparticles with graphene. Band gap engineering of graphene can effectively be achieved by doping it suitably. Chapter 6 describes different routes of doping graphene with boron and nitrogen. The arc discharge technique to prepare graphene has been effectively employed to chemically dope graphene. Chapter 7 presents chemical storage of H2 by graphene. To chemically store hydrogen in graphene, Birch-reduction and H2 plasma treatment have been employed