Trapping and sensing of hazardous insecticides by chemically modified single walled carbon nanotubes

The use of insecticides in agriculture is a common practice all over the world, but they are often known to be harmful towards the human body. This requires attention by experimentalists and theorists alike. In this work, using Born-Oppenheimer molecular dynamics (BOMD) and density functional theory (DFT) calculations, we have demonstrated the efficient trapping of several hazardous insecticide molecules on a carbon nanotube (CNT) surface. Our BOMD simulations suggest that under ambient conditions, though pristine CNTs are quite inefficient, transition metal atom (TM) incorporated nitrogen doped CNTs can trap the hazardous molecules at room temperature efficiently. Thorough investigations exhibit the presence of strong η⁶ bonding between the aromatic group of the pesticide and the TM adatom of the defective CNT, leading to the trapping of the molecules on the CNT surface. These CNTs are efficient trapping agents even in the presence of water and quite robust for any pesticides with aromatic group(s) in them. Furthermore, interestingly, the charge transfer interactions between the molecules and the defective CNTs lead to molecule specific optical absorption spectra of the composites, effectively developing defective CNTs as a detective optical sensor for pesticide molecules.