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Abstract
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Using the density functional theory calculations, we investigated the electronic properties of the armchair (6, 6) and (8, 8) and zigzag (8, 0) stanene based nanotubes as promising sensing materials for SO3 molecules. We analyzed the structural and electronic properties of the adsorption system including the adsorption energies, band structures and projected density of states. We examined both molecular and dissociative adsorption of SO3 on the aforementioned nanotubes. Different orientation of the SO3 molecule towards the nanotube gives rise to the different adsorption configurations. The results suggest that the molecular adsorption of SO3 on the nanotubes is more energetically favorable than the dissociative adsorption, indicating that SO3 tends to be molecularly adsorbed on the buckled nanotubes. Besides, the adsorption of SO3 molecule on the (8, 8) nanotube is much more favorable in energy than the adsorption on the (6, 6) one, suggesting that (8, 8) stanene based nanotube can react with SO3 molecule more efficiently. The considerable adsorption energy values indicate that SO3 molecule chemisorbed on the stanene based nanotubes. This is well confirmed by the large overlaps between the PDOS spectra of the interacting atoms. Mulliken charge analysis reveals a noticeable charge transfer from the stanene based nanotube to the adsorbed gas molecule, suggesting that SO3 acts as a charge acceptor. The calculated band gaps for the armchair (6, 6) and (8, 8) nanotubes are 0.33 and 0.24 eV, respectively while that of zigzag (8, 0) is estimated to be 0.207 eV, which indicate the semiconductor characteristics of the mentioned nanotubes. By analyzing the gas sensing response, we found that the stanene based nanotube would be promising SO3 sensor device. Our obtained results thus provide a theoretical basis for future fabrications of highly efficient sensing materials.
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