Environmentally hazardous gas sensing ability of MoS 2 -nanotubes: an insight from the electronic structure and transport properties.

Herein we have investigated the ability of the (6,6) MoS 2 -nanotube (NT) to sense environmentally hazardous electrophilic and nucleophilic gases using density functional theory (DFT). CO, CO 2 , H 2 O and NH 3 gases were chosen for adsorption on the (6,6) MoS 2 -NT and different adsorption parameters such as adsorption energy, projected density of states (PDOS), band structure and structural changes after adsorption were evaluated. Nucleophilic gases NH 3 and H 2 O showed a fairly high amount of electron density transfer from gas molecules to the NT while the opposite trend was realized for electrophilic gases CO and CO 2 . Among the four gases, H 2 O has the highest amount of adsorption energy (-1.74 eV) and a moderately high amount of charge transfer from H 2 O to the NT. Gas sensing behaviour was further rationalized from the enhanced I - V characteristics of gas adsorbed nanotubes compared to pristine ones. Analysis of results revealed that the (6,6) MoS 2 -NT showed a decent level of gas sensing properties towards CO, CO 2 , H 2 O and NH 3 gases, and high selectivity for H 2 O makes the MoS 2 -NT superior to previously reported MoS 2 -monolayer in this matter. These results suggest the possibility of fabrication of highly efficient MoS 2 -NT based gas sensors for environmentally hazardous gases.