Chemical Vapour Deposition of CNTs Using Structural Nanoparticle Catalysts

Abstract

This work examines the recent developments in non-traditional CCVD of CNTs with a view to determine the essential role of the catalyst in nanotube growth. A brief overview of the techniques reliant on the structural reorganization of carbon to form CNTs is provided. An in-depth analysis of CNT synthesis based upon ceramic, noble metal, and semiconducting nanoparticle catalysts is presented. Various approaches to germanium catalyst preparation are compared in terms of growth density and quality of synthesized nanotubes. Scanning electron microscopy measurements indicate that a technologically relevant density is achievable using non conventional catalysts. Raman measurements have identified the synthesized nanotubes as single walled and, in terms of graphitization and structure, of a high quality. Extensive atomic force microscopy characterisation of the catalyst has been undertaken in order to ascertain the influence of morphology on the ability of the catalyst to yield CNT growth. A model for CNT growth consistent with the experimental results is proposed