The Theoretical Study Of Gas Adsorption On Doped MoS₂ And The Preparation Of Nitrogen-doping MoS₂

Recently, MoS₂ gained attention in the field of toxic gas sensors and hydrogen storage materials, and these two areas basically belong to the gas adsorption. Based on the first principle, substitutional Al, Si, P, N doped MoS₂ were analyzed to investigate the adsorption properties of three kinds of gas molecules NO₂, NH₃ and H₂. We also prepared Nitrogen doped MoS₂ nanosheets.By using the generalized gradient approximation, 4×4×1 monolayer MoS₂ is used to study NO₂ and NH₃ gas adsorption. For the pristine MoS₂, both adsorption energy and charge transfer amount are small, the adsorption effect is not obvious. After monolayer MoS₂ by Al, Si, P, N substituted doping at S site, gas adsorption ability of doped MoS₂ is enhanced, adsorption energy and charge transfer increase obviously, dopant atoms become the charge transfer link and the bridge between gas molecules and monolayer MoS₂. Of four kinds of doping systems, the adsorption effect of Si doped MoS₂ is the best, the adsorption energy of NO₂ and NH₃ molecules are respectively-2.588 and-2.156 eV, the amount of charge transfer are 0.52 and 0.23 electrons.By using the local density approximation, 3×3×1 monolayer MoS₂ is used as research object, H₂ molecules adsorption is studied. The adsorption effects of doped 3×3×1MoS₂ have greatly improved compared with pristine MoS₂. When H₂ adsorbs on the Si doped MoS₂, the adsorption energy is-0.420 eV. When ten H₂ molecules adsorb on the Si doped MoS₂, the adsorption energy is-0.2eV/H₂, the hydrogen adsorption concentration reaches 1.37wt%, has the great prospects in the field of hydrogen storage.At the end of this paper, hydrothermal method and sol-gel method are applied to prepare MoS₂ nanoflower and Nitrogen doped MoS₂ nanosheets. The prepared MoS₂ nanoflower has special petal structure, good dispersion, large surface area, active sites. Layered structure can be clearly seen for both MoS₂ nanoflowers and N-doped MoS₂ nanosheets. For N-doped MoS₂ nanosheets, X-ray photoelectron spectroscopy proves the N-Mo bond which confirms the substitutional doping of N at the S sites on MoS₂. This paves the way for theory and application research on substitution at S sites.