Simulations Predict Unexpected Behavior of Metallic and Semiconducting Nanotubes

An accurate description of the interactions between gas molecules and SWNTs is important for designing better materials for adsorption and purification of fluids using these nanoporous materials. Towards this, Center for Simulation and Modeling (SaM)-affiliated researchers De-Li Chen, Wissam A. Saidi, and J. Karl Johnson recently published two papers, in conjunction with collaborators at Penn State and the University of Virginia where atomistic simulations were used to predict the outcome of experiments carried out by their colleagues at UVa. The papers were published in the Journal of the American Chemical Society, 135, 7768-7776 (2013) DOI: 10.1021/ja402928s and Physical Review Letters, 110 135503 (2013) DOI: 10.1103/PhysRevLett.110.135503. The calculations predicted that the interaction energies between gases and either metallic or semiconducting single walled carbon nanotubes (SWNTs) would be the same, as long as the diameters of the nanotubes were the same. Specific calculations were carried out for adsorption of noble gases and n heptane on a series of nanotubes that were either metallic or semiconducting, having similar diameters. The theoretical predictions were confirmed by temperature programmed desorption experiments carried out at UVa on samples of purified metallic or semiconducting SWNTs.