Investigations of new methods of synthesis, phenomena and novel properties of nanocarbons and other nanomaterials

Abstract

This thesis consists of seven Chapters. Chapter 1 gives a brief overview of nanomaterials. Chapter 2 consists of two parts of which Part 1 describes efforts towards phase transfer of nanocrystals of gold and CdSe from aqueous or organic medium to a fluorous medium and solubilization of ZnO nanorods and carbon nanotubes in a fluorous medium. Part 2 deals with the one-step synthesis of fluorouscapped nanoparticles of metal chalcogenides such as CdSe, CdS, PbSe, ZnSe and of metal oxides such as γ-Fe2O3 and ZnO and of bimetallic FePt. Chapter 3 describes the use of the Huisgen cycloaddition reaction to generate assemblies of metal (gold) and semiconductor (CdSe) nanoparticles as well as to covalently attached SWNT-gold and -CdSe nanoparticle composites. Connecting carbon nanotubes by click chemistry is also reported. Investigations on the dependence of magnetic and optical properties of nanoparticles with interparticle distance are discussed in Chapter 4. Magnetic properties are examined with FePt nanoparticles while spectroscopic properties are examined in the case of CdSe nanoparticles. Chapter 5 consists of two parts with Part 1 dealing with a spectroscopic study of charge-transfer interactions of electron-withdrawing (nitrobenzene, TCNQ and TCNE) and electron-donating (TTF and aniline) molecules with single-walled carbon nanotubes (SWNTs). In Part 2, the effect nanoparticles of metals such as gold and platinum on the electronic structure of SWNTs has been studied by Raman spectroscopy. Chapter 6 consists of three parts. Part 1 describes the separation of metallic and semiconducting SWNTs based on molecular charge-transfer while Part 2 deals with a novel method for the synthesis of metallic SWNTs by an arc-discharge method. An arc-discharge method has also been employed to prepare Y-junction SWNTs (Part 3). In Chapter 7, sensitivity of the electronic structure of graphene towards various electron-donor and acceptor molecules has been studied by Raman and optical absorption spectroscopy as well as electrical resistivity measurements.