Surface functionalization of CNTs by a nitro group as a sensor device element: theoretical research

The problem of modifying carbon nanotubes (CNTs) by functional groups is relevant in connection with the intensive development of the nanoindustry, in particular, nano- and microelectronics. For example, a modified nanotube can be used as a sensor device element for detecting microenvironments of various substances, in particular, metals included in salts and alkalis. The paper discusses the possibility of creating a highly efficient sensor using single-walled carbon nanotubes as a sensitive element, the surface of which is modified with the functional nitro group —NO2. Quantum-chemical research of the process of attaching a nitro group to the outer surface of a single-walled CNTs of the (6, 0) type were carried out, which proved the possibility of modifying CNTs and the formation of a bond between the —NO2 group and the carbon atom of the nanotube surface. The results of computer simulation of the interaction process of a surface-modified carbon nanotube with alkali metal atoms (lithium, sodium, potassium) are presented. The sensory interaction of a modified carbon nanosystem with selected metal atoms was investigated, which proved the possibility of identifying these atoms using a nanotubular system that can act as a sensor device element. When interacting with alkali metal atoms in the “СNT – NO2” complex, the number of major carriers increases due to the transfer of electron density from metal atoms to the modified CNTs. The results presented in this paper were obtained using the molecular cluster model and the DFT calculation method with the exchange-correlation functional B3LYP (valence split basis set 6-31G).