Adsorption of a methanol molecule on a ZnO nanotube was investigated by using density functional calculations in terms of energetic, geometric, and electronic properties. The adsorption energy is found to be in the range of −23.4 to −220.7 kJ/mol. The electronic properties of the tube strongly depend on the orientation of the methanol on the nanotube surface. When the methanol attacks a hexagonal ring of the tube via its methyl hydrogens, the highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap of the tube is significantly decreased from 2.27 to 1.53 eV, and, therefore, it becomes more conductive. This suggests that a pristine ZnO nanotube may generate an electrical signal in the presence of methanol molecules, making it a potential candidate for methanol detection.
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