The adsorption of SO2 on TiO2 anatase nanoparticles: a density functional theory study

Abstract

First-principles calculations have been carried out to investigate the adsorption properties of SO2 molecules on nitrogen-doped TiO2 anatase nanoparticles using the density functional theory method to fully exploit the gas-sensing capabilities of TiO2 particles. For this purpose, we have mainly studied the adsorption of the SO2 molecule on the dangling oxygen atom and doped nitrogen atom sites of the TiO2 nanoparticles because these sites are more active than other sites in the adsorption processes. The complex systems consisting of the SO2 molecule positioned toward the undoped and nitrogen-doped nanoparticles have been relaxed geometrically. The results presented include structural parameters such as bond lengths and bond angles and energetics of the systems such as adsorption energies. The electronic structure and its variations resulting from the adsorption process, including the density of states, molecular orbitals, and the charge transfer, are discussed. We found that the adsorption of the SO2 molecule on the nitrogen-doped TiO2 nanoparticles is energetically more favorable than the adsorption on the undoped ones. These results thus provide a theoretical basis for the potential applications of TiO2 nanoparticles in the removal and sensing of SO2 and give an explanation for helping in the optimization of improved gas removers and sensor devices.