مشخصات پژوهش

Using the density functional theory calculations, we investigate the adsorption behaviors of NO2 and O3 molecules on the pristine and N-doped TiO2 anatase nanocrystals based on the energetics, structural parameters, charge transfer and electronic structure. We determine the most stable adsorption positions of NO2 and O3 molecules on TiO2 nanocrystals and the styles of molecule binding to the surface, and examine the interaction between gas molecules and TiO2. The results suggest that the sensing performance of nitrogen modified TiO2 nanocrystal is superior to the pristine one, indicating the strong interaction and charge transfer between gas molecules and N-doped TiO2. Mulliken charge analysis indicates that both NO2 and O3 molecules serve as charge acceptors from the TiO2 nanocrystal. The adsorption on the N-doped nanocrystal is more favorable in energy than that on the pristine one, which indicates that nitrogen doping plays a critical role in the process of adsorption. We further examine the variation of the electronic structure for gas molecules adsorption on the considered nanocrystals. The charge density difference calculations show that the electronic density increases at the middle of the newly formed bonds. We also analyzed the molecular orbitals for the studied systems, which indicate that the electronic density in the LUMOs is high on the adsorbed molecules, whereas the HOMOs are mainly localized over the TiO2 nanocrystal. The nontrivial sensitivity and high adsorption ability of N-doped TiO2 nanocrystal represent that it has a potential application in the field of highly efficient gas sensors and high performance catalysts.