Electronic and Optical Properties of Single-Walled Carbon Nanotube Functionalized by CH3COOH

Organic functionalization of carbon nanotubes (CNTs) plays very important role in the development of electrochemical biosensors. In this study, pristine (5,5) carbon nanotube was functionalized by Ethanoic Acid (CH3COOH) using First Principles Density Functional Theory (DFT). It was found that the encapsulation of CH3COOH into the (5,5) CNT is endothermic due to the small diameter of the tube. However, interacting it outside the sidewall of the tube gives an exothermic process indicating a stable geometry. Accordingly, additional electronic bands and peaks are observed in the electronic structures of the functionalized CNT. Further, it was shown that that the p orbitals of the oxygen atoms and carbon atoms of the acid are the main contributors of the additional peaks in the valence and conduction regions, respectively. Finally, there were observed optical transitions in the functionalized CNT caused by the hybridization of the armchair CNT. Evidently, this study provided insights on more potential applications of carbon nanotubes as biosensors.