Gas Adsorption On MoS₂ Nanotube From The First Principle Study

Environmental pollution detection is of great significance for public health monitoring and industrial and agricultural development. Many research achievements have demonstrated that the two-dimensional ?2D? MoS₂ has great potential in gas detection. The field-effect-transistor ?FET? based on MoS₂ performs well in the gas detection. However, present studies have also shown that it has some disadvantage. For example:when the single-layer MoS₂ FET was used in the detection of NO molecules, the current is unstable. Meanwhile, the developments in the researches about MoS₂ nanotubes in the recent years have brought more opportunities for the advancement in the gas sensors based on MoS₂. No reports about the capacity, stability and sensitivity of the MoS₂ nanotubes for detecting gases compared to the MoS₂ sheet have been conducted. Researching on this issue is of great significance for the MoS₂ materials application in the electronic gas sensors.In our work, we adopt the GGA function to carry on the research about the ability of the single-wall ?n, n?, ?n,0? MoS₂ nanotube detecting NO, NO₂, CO, SO₂, and NH₃ gas molecules compared to the MoS₂ monolayer. The most stable adsorption configurations, adsorption ener-gies, and charge transfers are calculated in our recent work. The conclusions are as follows: ?1? these gas molecules are physisorptions on the MoS₂ monolayer and nanotubes; ?2? Among these gas molecules, the NO molecule has the biggest interaction with the MoS₂ nanotube and monolayer; ?3? the nanotube model can improve the capacity of MoS₂ monolayer for detectin-g these molecules, especially for NO; ?4? NO adsorption energy decreases for the wider MoS₂ nanotube.Considering that GGA function can't deal well with the weak intermolecular interactions, we chose the method of optB88-vdW which considers the effects of van der Waals force between the the NO molecules and the MoS₂ nanotube and monolayer, respectively. The conclusions demonstrate that the adsorption energies based on optB88-vdW method are significantly greater than the GGA-PBE method. We also get the conclusion that MoS₂ nanotubes model can effectively improve the NO gas detection ability of MoS₂ materials and the smaller the diameter of MoS₂ nanotubes is, the stronger the detection ability is.Based on the theoretical studies in this paper, it is predicted that replacing the MoS₂ mon -olayer with the nanotube with a smaller diameter as the channel materials should increase the stability and sensitivity of MoS₂-based FET sensors in detecting NO gas. The continuous re--search on the factors that affecting the adsorption performance of the MoS₂ materials is con-ducive to the development of MoS₂ materials in gas detection application potential.