High Coverage of H2, CH4, NH3 and H2O on (110) SnO2 Nanotubes

Abstract

We start with short review of inorganic nanotubes leading to gas sensors, which among others, can be important application of semiconductor oxides. We investigate the interaction of H2, CH4, NH3 and H2O gases at high internal and external coverage with the [(SnO2)18]3 nanotube designed from the (110) plane of SnO2 in the rutile structure. We have used the PM7 and DFT methods, and B3LYP as the functional with Huzinaga and LANL2DZ basis sets to determine adsorption energies, interatomic distances, LUMO, HOMO, energy gaps and hardness. DFT was used in order to investigate these systems formed by the high coverage of internal and external adsorbed gases on the nanotube. The adsorption energies, and inter/intra atomic distances indicate stronger interaction of the nanotube with the NH3 and H2O gases. Our calculated adsorption energies, interaction distances, energy gaps and sensitivity trends are in agreement with reported theoretical and experimental values. For these large systems (~1000 atoms), it is observed that the selected computational methods, despite their lower computational demand, can provide satisfactory physical/chemical insights. The intermolecular distances of the adsorbed gas suggest hydrogen bonding among the adsorbed gases of H2O and NH3 which helps to stabilize the interaction process.