Improving the Sensing Behavior of Acetone on Carbon Nanotube with the Application of Explosives Detection

Detection of acetone gas is important to detect explosives produced from acetone in terrorist bombings, medical diagnostics and environmental protection against pollutants. In this study, using density-functional theory (DFT), the acetone sensing enhancement of carbon nanotubes decorated with zinc oxide nanowires (CNT/ZnO) was investigated. It was shown that the adsorption of acetone on pure carbon nanotubes (CNT) is done physically with an adsorption energy of -0.64 eV, but by decorating the nanotubes with zinc oxide nanowires (ZnO), the maximum adsorption energy of -2.43 eV is obtained at the connection level of the nanowire to the nanotube. It was also shown that by increasing the length of ZnO, the adsorption intensity depending on the adsorption location, increases at the contact point of ZnO to CNT and decreases at points far from contact surface, respectively. By examining the changes in the energy band diagram and density of states (DOS) of pure and decorated structures, it was observed that the adsorption of acetone does not cause much change in the bandgap or DOS of CNT, but the adsorption of this gas on CNT/ZnO is in a way that by shifting the DOS to lower energies, it changes the electronic nature of this nanostructure. The results showed that CNT decoration with ZnO, would have a special effect on improving its sensing performance in acetone gas detection. Using the introduced structure is preferable than other gas sensors due to its small size and room-temperature operation for defense applications such as smartening of security inspection systems.