title: Hydrogen in chemical vapour deposited carbon nanotubes: an active site for functionalization.
abstract: The presence of hydrogen in as-grown carbon nanotubes (CNTs) synthesized by microwave plasma (MP) chemical vapour deposition (CVD) technique is demonstrated. Our results showed that the MPCVD, as-grown CNTs were hydrogenated consisting of C-H bonds; whereas, the tubes synthesized by arc discharge consisted of non-hydrogenated multi-walled CNTs. Fourier transform infrared spectroscopy (FTIR) and micro-Raman spectroscopy techniques were used to detect C-H bonding in the as-grown CNTs. The effective functionalization of as-grown hydrogenated CNTs grown using a microwave CVD process is first time demonstrated by laser assisted CVD process. It was found that the laser-assisted CVD process resulted in the termination of hydrogen and the oxidation of as-grown CNT structure leading to the carboxylic group attachment. The FTIR results show the presence of -OH and C=O bonds in the functionalized samples. However, the non-hydrogenated CNTs could not be effectively functionalized by the same process, probably due to the fact that it did not contain active sites pre-requisite for functionalization, as did the CVD grown samples. The functionalization of CVD grown tubes is believed to take place at the 'active' hydrogen-terminated sites on the CNT surfaces.
authors.affiliation: Department of Mechanical Engineering, University of Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: E
authors.initials: E
authors.lastname: Titus
authors.forename: Gil
authors.initials: G
authors.lastname: Cabral
authors.forename: J C
authors.initials: JC
authors.lastname: Madaleno
authors.forename: M C
authors.initials: MC
authors.lastname: Coelho
authors.forename: P Ramesh
authors.initials: PR
authors.lastname: Babu
authors.forename: W J
authors.initials: WJ
authors.lastname: Blau
authors.forename: D S
authors.initials: DS
authors.lastname: Misra
authors.forename: J
authors.initials: J
authors.lastname: Gracio