Abstract
First-principle calculations within density functional theory were performed to investigate the interactions of NO and NO2 molecules with TiO2/MoS2 nanocomposites. Given the need to further comprehend the behavior of the NOx molecules positioned between the TiO2 nanoparticle and MoS2 monolayer, we have geometrically optimized the complex systems consisting of the NOx molecule oriented at appropriate positions between the nanoparticle and MoS2 monolayer. The structural properties, such as bond lengths, bond angles, adsorption energies and Mulliken population analysis, and the electronic properties, including the density of states and molecular orbitals, were also analyzed in detail. The results indicate that the interactions between NOx molecules and N-doped TiO2 in TiO2-N/MoS2 nanocomposites are stronger than those between gas molecules and undoped TiO2 in TiO2/MoS2 nanocomposites, which reveal that the N-doping helps to strengthen the interaction of toxic gas molecules with hybrid TiO2/MoS2 nanocomposites. The N-doped TiO2/MoS2 nanocomposites have higher sensing capabilities than the undoped ones, and the interaction of NOx molecules with N-doped nanocomposites is more favorable in energy than the interaction with undoped nanocomposites. Therefore, the obtained results also present a theoretical basis for the potential application of TiO2/MoS2 nanocomposite as an extremely sensitive gas sensor for NO and NO2 molecules.
Highlights
Titanium dioxide (TiO2, Titania) has aroused great attentions as an important semiconductor material due to its effectiveness and outstanding properties, such as nontoxicity, low cost, high catalytic efficiency, photoactivity [1], and stability
The results indicate that the interactions between NOx molecules and N-doped TiO2 in TiO2-N/MoS2 nanocomposites are stronger than those between gas molecules and undoped TiO2 in TiO2/MoS2 nanocomposites, which reveal that the N-doping helps to strengthen the interaction of toxic gas molecules with hybrid TiO2/MoS2 nanocomposites
Where E(composite ? adsorbate) is the total energy of the adsorption system, Ecomposite is the energy of the TiO2/ MoS2 nanocomposite, and Eadsorbate represents the energy of non-adsorbed NOx molecules
Summary
Titanium dioxide (TiO2, Titania) has aroused great attentions as an important semiconductor material due to its effectiveness and outstanding properties, such as nontoxicity, low cost, high catalytic efficiency, photoactivity [1], and stability. Numerous electronic devices were made using the few-layer MoS2 as an important component, such as field-effect transistors [17], sensors [18], etc. Several computational studies of N-doped TiO2 anatase nanoparticles and fewlayer MoS2 structures have been separately published, describing some of the main electronic and physical properties of these materials. The gas-sensing capabilities of MoS2-based field-effect transistors and sensing films for NO and NH3 were experimentally revealed with an enhanced sensitivity in some other works [19, 20]. The interaction of NOx molecules with TiO2/MoS2 nanocomposites has been investigated by density functional theory (DFT) computations. The main aim of this study is to supply an overall understanding on the adsorption behaviors of nano-TiO2/MoS2 composites as highly sensitive NOx sensors
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