Improving the adsorption of sulfur trioxide on TiO2 anatase nanoparticles by N-doping: A DFT study

Abstract

The adsorptions of sulfur trioxide molecule on undoped and N-doped TiO 2 anatase nanoparticles were investigated by density functional theory (DFT) calculations. N-doped nanoparticles were constructed by substitution of oxygen atoms of TiO2 by nitrogen atoms. The results showed that the adsorption energies of SO3 on the different nanoparticles following the order N-doped (N site)>N-doped ( O D site)>Undoped ( O D site). We provide the electronic structure of the nanoparticles, as well as complex systems containing the sulfur trioxide molecule and discuss the key issues that influence the adsorption process. The structural properties including the bond lengths, bond angles and adsorption energies and the electronic properties including the projected density of states (PDOSs) and molecular orbitals (MOs) have been mainly analyzed in detail. The obtained results indicate that the interaction between SO 3 molecule and N-doped TiO 2 nanoparticle is stronger than that between SO 3 and undoped nanoparticle, which suggests that N-doping helps to strengthen the interaction of SO 3 with TiO 2 anatase nanoparticles. It is shown that although SO 3 molecule has no significant interaction with undoped nanoparticle, it tends to be strongly adsorbed to N-doped anatase nanoparticles with considerable adsorption energies, being as an effective property to be utilized in gas sensing applications. We also note at this point that the titanium atom and the doped nitrogen atom sites are more active than the dangling oxygen site, which reveals that the titanium and doped nitrogen sites provide more stable adsorption geometries.