Curvature effect in the longitudinal unzipping carbon nanotubes: A DFT study

Density functional theory (DFT) calculations are performed to analyze curvature effects in the oxidative longitudinal unzipping of carbon nanotubes (CNTs) of different diameters. The reactions considered involve the adsorption of permanganate, followed by the oxidation of the nanotube, which results in dione and hole formation. The study was performed with armchair CNTs of different diameters and with corrugated graphene layers, which emulate the curvature of CNT of larger radii, with the finding that the curvature and the pyramidalization angle of the these structures strongly affects the stability of the intermediate dione structure formed during the unzipping process. Permanganate adsorption energies increase for more curved surfaces promoting the oxidation reaction in surfaces of small radius, making this reaction spontaneous for small radius. The second permanganate adsorbs on the parallel carbon–carbon bond to first diona formation resulting the longitudinal unzipping of the CNT.