Functionalization of carbon nanotube by carboxyl group under radial deformation

Highlights: • Structural and the electronic properties of carboxylated (5,5) single-walled carbon nanotubes (SWNT) under pressure. • sp3 hybridization induced by the functionalization and/or deformation of SWNT. • Functionalization of SWNT by –COOH under pressure for nanobiotechnological application. - Abstract: The dependence of the structural and the electronic properties of functionalized (5, 5) single-walled carbon nanotubes (SWNT) were investigated through ab initio density functional simulations when the carboxyl group is bonded on the flatter or curved regions. Radial deformations result in diameter decrease of up to 20 per cent of the original size, which was the limit reduction that maintains the SWNT functionalized structure. Changes on the electronic structure were observed due to the symmetry break of the SWNT caused by both the carboxyl group and the C–C bond distortions resulted by the radial deformation. It is observed that the functionalization process is specially favored by the sp3 hybridization induced on the more curved region of the deformed SWNT