Electronic structures and dielectric function of (5, 5) CNT-C2H4O system: A first-principles study on the detection capability of CNT for gas sensing applications

Carbon nanotubes (CNTs) are known to have a wide range of applications in various fields of discipline. In this research, the ability of metallic armchair (5, 5) CNT to detect acetaldehyde (C H O) was investigated using first-principles density functional theory (DFT) as implemented in Quantum ESPRESSO with the Generalized Gradient Approximation (GGA). Accordingly, it was found that C H O preserved the metallic behavior of the CNT. However, some bands are found to have overlapped in both the valence and conduction regions of the electronic structures of the resulting system that are mainly caused by the p orbitals of the oxygen and carbon atoms of the compound. These are further confirmed by the projected density of states (pDOS). Moreover, optical transitions are observed in both the real and imaginary parts of the dielectric function caused by the interband transitions between the Van Hove singularities of the electronic structures. In all circumstances, this research has provided more insights into the potential gas sensing applications of metallic CNTs.