Title: From metallic to semiconductor conversion of single –walled carbon nanotubes by chlorination

Abstract

In this research, the single-walled carbon nanotubes (SWCNTs) were treated with strong HClO4 acid (98 %). The obtained doped nanotubes were investigated firstly by UV-vis-NIR absorption, Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy; and secondly by numerical calculations based on density functional theory (DFT) using generalized gradient and local density approximations (GGA and LDA) as implemented in SIESTA code. The results show significant changes in the behavior of metallic nanotubes. Indeed, a new pick attributed to the C-Cl stretching vibration was obtained in FTIR measurements, while the Breit-Wigner-Fano signature corresponding to the metallic character disappears from the Raman G-band. Secondly, the first-principles density functional theory calculations (GGA and LDA) show that the adsorption of chlorine atoms on the metallic (9, 9) carbon nanotubes wall (one Cl atom for 36 C atom) generates an energy gap in the electronic structure of these nanotubes, confirming the experimental results. This highlights a conversion of the metallic nanotube to semiconductor.

Biography

Mourad Berd is a senior lecturer in physics at the University of Bejaia in central eastern Algeria. He obtained his Ph.D. in materials physics at the University Mouloud Mameri of Tizi-Ouzou in collaboration with the CEMES -Toulouse – France. He worked on carbon nanotubes, fullerenes and peapods. He is interested in 2D materials and their composites as potential candidates for anode materials for Li-ion batteries or for hydrogen storage. For the last two years, he has been interested in ab. initio computational methods based on density functional theory using the computer code siesta for the study of nanomaterial properties.