Prediction of a highly sensitive molecule sensor for SOx detection based on TiO2/MoS2 nanocomposites: a DFT study

摘要

First principles calculations within density functional theory have been carried out to investigate the adsorptions of SOx (x=1, 2) molecules on TiO2/MoS2 nanocomposites in order to fully discover the gas sensing capabilities of TiO2/MoS2 composite systems. The van der Waals interactions were included to obtain the most stable geometrical structures of TiO2/MoS2 nanocomposites with adsorbed SOx molecules. SOx molecules preferentially interact with the doped nitrogen and fivefold coordinated titanium sites of the TiO2 anatase nanoparticles because of their higher activities in comparison with the other sites. The results presented include structural parameters such as bond lengths and bond angles and energetics of the systems such as adsorption energies. The variation of electronic structures are discussed in view of the density of states and molecular orbitals of the SOx molecules adsorbed on the nanocomposites. The results show that the adsorption of the SOx molecule on the N-doped TiO2/MoS2 nanocomposite is energetically more favorable than the adsorption on the undoped one, implying that the nitrogen doping helps to strengthen the interaction of SOx molecules with TiO2/MoS2 nanocomposites. These calculated results thus provide a theoretical basis for the potential applications of TiO2/MoS2 nanocomposites in the removal and sensing of harmful SOx molecules.