The Theoretical Study On Electronic Properties Of WO₃ Nanowire-NO₂ Adsorption System And Ti Doping

This paper based on the calculation method of first-principles density functional, using MS?Materials Studio? software, studied the electrical properties of WO₃ nanowires and the adsorption performance of NO₂ gas. Based on the experiments of WO₃ nanowires growth direction, we establishedthe adsorption model of the NO₂ molecules on WO₃?001? and?010? nanowire surface, calculated the adsorption energy, electronic structure, atomic Mulliken charge population, charge density differences and electron localization functions?ELF?,analysed the NO₂ gas adsorption performance of the different WO₃ nanowires growth direction.Compared with the adsorption energy, for the NW001 and NW010, NO₂ adsorption on the O₂ c site presents the lowest Eads value and therefore is the most stable and likely adsorption structure.DOS with the band diagram shows that adsorption of NO₂ will introduce new impurity peak in the DOS of the nanowires,change the band gap, makes the Fermi level moves toward the gapand then decrease the charge carrier concentration. Mulliken population and charge density differences show that the gas sensor based on [010]-oriented WO₃ nanowires is expected to yield significantly higher NO₂ sensitivity than that based on [001]-oriented nanowires.Then we continue to study Ti doped WO₃?010? nanowires the influence of adsorption performance. Calculated energy shows, compared with the pure nanowires, the energy of the doped nanowires were improved, the doping makes reduced stability of nanowires. Compared before and after doping nanowires DOS figure, it found the doping introduce new impurity peak in the DOS of the nanowires, Ti atoms interact with the surrounding neighboring atoms each other, make the electronic wave function overlap, change the band gap of WO₃ nanowires, and make the Fermi level up, conductive performance enhancements. Mulliken population and charge density differences show that Ti doped lead to more electronic transfer to NO₂ from WO₃ nanowires, suggests that Ti doping modification is an effective means to improving WO₃ nanowires sensor sensitivity.In addition, whether pure WO₃ nanowires, or Ti doped WO₃ nanowires, we set up other gas?O₃?NO?NH₃?H₂S? adsorption model, by the comparison and analysis, WO₃ nanowires on NO₂ gas can be showed the good sensitivity and selectivity.