Transition metal-carbon nanotube hybrid materials

Abstract

Carbon nanotubes are one of the most intensively explored nanostructured materials. In particular, carbon nanotubes are unique and ideal templates onto which to immobilize nanoparticles allowing the construction of designed nanoarchitectures that are attractive to diverse potential applications such as supports for catalysts, hydrogen storage media, and related technologies that exploit the inherent smallness and hollow characteristics of the nanoparticles. However, understanding of the interaction between transition metal and carbon nanotubes remains a challenging issue. Interaction of the transition metal atom with the intrinsic and extrinsic defect sites in the carbon nanotubes has been studied through density functional theory calculations. Based on calculation results, it was experimentally shown that transition metal nanoparticles attached to carbon nanotubes can be established by utilizing these defects without functionalization process that resulting in the deterioration of properties of carbon nanotubes. The interaction of the Ni atom, as a representative of the transition metal, with three intrinsic defects in carbon nanotubes was investigated. The results show that intrinsic defects have a significant effect on the Ni binding energies and on the structures of carbon nanotubes. The introduction of defects can enhance the Ni binding energies for carbon nanotubes. Besides the intrinsic defects, enhancement of metal adsorption stability is also anticipated by extrinsically doped element. To understand how nitrogen atoms are distributed in the carbon nanotubes, the nature of nitrogen atoms in carbon nanotubes with differing diameters and helicities was systematically studied. It was found that the bonding configuration of nitrogen is dependent on the diameter and helicity as well as whether there exists a carbon vacancy. In the presence of a carbon vacancy, three nitrogen atoms with pyridine-like bonding configuration neighboring a carbon vacancy are t...