Figure Legend: Geometric configuration of the structures: (a) CNT, (b) COOH-CNT, (c) OH- CNT and geometric structures of the systems with their minimized energies: (d) CNT-Pb, (e) COOH-CNT-Pb, (f) OH-CNT-Pb.
Journal Reference
Applied Surface Science, Volume 285, Part B, 15 November 2013, Pages 198–204.
M. Bastos , I. Camps.
Laboratório de Modelagem Computacional – LaModel, Instituto de Ciências Exatas, Universidade Federal de Alfenas – Unifal-MG, CEP 37130-000 Alfenas, Minas Gerais, Brazil.
Abstract
Absorption of Pb on a zigzag (10, 0) carbon nanotube (CNT) surface, pure and functionalized with carboxyl (COOH) and hydroxyl (OH) groups was investigated using the density functional theory. Binding energy calculations were performed and indicated that adsorption of the Pb metal on the surface of the three nanotubes were stable, through a chemisorption. Therefore, CNTs are a feasible active material for filters that retain such metal. After Pb adsorption, the CNT and COOH-CNT conductivity changed, from semiconductor to half-metallic for CNT and from semiconductor to metallic for COOH-CNT, which can serve as a signal for Pb sensor. In all three cases adsorption produced a change in nanotube magnetism, which can also serve as a sensitive signal for chemical sensors. After adsorption of Pb, the changes in binding energy, charge transfer, conductance and magnetism may lead to the different response in the CNTs-based sensors. Thus, it is expected that these results could provide helpful information for the design and fabrication of the Pb sensing devices.