Shu Peng

Chemical control of nanotube electronics

The possibility of modifying the electronic properties of nanotubes using gas molecule adsorption is investigated using the first-principles total energy density functional calculations. Detailed analysis of the electronic structures and energetics is performed for the semiconducting (10,0) single-walled carbon nanotube interacting with several representative gas molecules (NO2, NH3, CO, O2, and H2O). The results elucidate the mechanisms of the adsorption-induced nanotube doping and illustrate an example of the simulation-based design characterization of nanoelectronic components.

Carbon nanotube reservoirs for self-healing materials

A novel nanoreservoir made of carbon nanotubes (CNTs) is proposed for realizing tougher and automated self-healing materials. The advantages of the approach are that CNTs have the potential to play the role of reinforcing elements prior to and after sealing a crack and that the number of voids is reduced after the material and the CNTs themselves are healed. The focus of this paper is on investigating the feasibility of using CNTs as a nanoreservoir by analyzing the dynamics of a fluid flowing out of a ruptured single-walled CNT (SWNT), where the fluid resembles an organic healing agent. With this in mind the escaping mechanism of organic molecules stored inside a cracked SWNT was investigated through a molecular dynamics study. The study shows that, when a SWNT wall suffers the formation of a crack, a certain amount of organic molecules, stored inside the SWNT, escape into space in a few picoseconds. This phenomenon is found to depend on the temperature and on the size of the cracks. The results of this study indicate that CNTs have the potential to be successfully used to realize the next generation of stronger, lighter and self-healing materials.

First-principles study of band-gap change in deformed nanotubes

The effects of cross-sectional deformation and bending on the electronic structures of single-wall carbon nanotubes (SWNTs) are examined. Upon increasing the deformation, semiconducting SWNTs undergo semiconductor-metal transition, and the conduction band and valence band show asymmetric response to the deformation. The metallic tubes’ electronic structures are relatively insensitive to similar mechanical deformation. Using the properties of deformed nanotubes, we propose a conceptual design of SWNT-based single-electron quantum-well devices.

Nano Electro Mechanics of Semiconducting Carbon Nanotube

The effect of a flattening distortion on the electronic properties of a semiconducting carbon nanotube is investigated through first-principles calculations. As a function of the mechanical deformation, electronic bandgap is reduced leading to a semiconductor-metal transition. However, further deformation reopens the bandgap and induces a metal-semiconductor transition. The semiconductor?metal transitions take place as a result of curvature-induced hybridization effects, and this finding can be applied to develop novel nano electro mechanical systems. ©2002 ASME

Ab initio Study of Metal Atoms on SWNT Surface

Abstract : Interactions of metal atoms (Al, Ti) with semiconducting single walled carbon nanotube (SWNT) are investigated using first-principles pseudopotential calculations. Six different adsorption configurations for aluminum and titanium atoms are studied. Comparison of the energetics of these metal atoms on (8,0) SWNT surface shows significant differences in binding energy and diffusion barrier. These differences give an insight to explain why most of metal atoms (such as Al) form discrete particles on nanotube while continuous nanowires are obtained by using titanium in the experiment.