Improvement of gas-adsorption performances of Ag-functionalized monolayer MoS2 surfaces: A first-principles study

Abstract

Investigations of the adsorptions of representative gases (NO2, NH3, H2S, SO2, CO, and HCHO) on different Ag-functionalized monolayer MoS2 surfaces were performed by first principles methods. The adsorption configurations, adsorption energies, electronic structure properties, and charge transfer were calculated, and the results show that the adsorption activities to gases of monolayer MoS2 are dramatically enhanced by the Ag-modification. The Ag-modified perfect MoS2 (Ag-P) and MoS2 with S-vacancy (Ag-Vs) substrates exhibit a more superior adsorption activity to NO2 than other gases, which is consistent with the experimental reports. The charge transfer processes of different molecules adsorbed on different surfaces exhibit various characteristics, with potential benefits to gas selectivity. For instance, the NO2 and SO2 obtain more electrons from both Ag-P and Ag-Vs substrates but the NH3 and H2S donate more electrons to materials than others. In addition, the CO and HCHO possess totally opposite charge transfer directs on both substrates, respectively. The BS and PDOS calculations show that semiconductor types of gas/Ag-MoS2 systems are more determined by the metal-functionalization of material, and the directs and numbers of charge transfer process between gases and adsorbents can cause the increase or decline of material resistance theoretically, which is helpful to gas detection and distinction. The further analysis indicates suitable co-operation between the gain-lost electron ability of gas and metallicity of featuring metal might adjust the resistivity of complex and contribute to new thought for metal-functionalization. Our works provide new valuable ideas and theoretical foundation for the potential improvement of MoS2-based gas sensor performances, such as sensitivity and selectivity.

Defect engineered MoSSe Janus monolayer as a promising two dimensional material for NO2 and NO gas sensing

“…The Fermi level of MoSSe monolayer lies between the highest occupied molecular orbital (HOMO) and lowest occupied molecular orbital (LUMO) of NH 3 , and this suitable position of energy levels is the main source of noticed charge transfer from the NH 3 molecule to monolayer 53 . This is consistent with other reports showing the adsorption of NH 3 on MoS 2 and WS 2 monolayer giving rise to the donor behavior, whereas the adsorption energy is higher for MoSSe Janus monolayer than the previous reports 9,17,19,53,54 .…”

“…The charge transfer mechanism is a basic working mechanism in two-dimensional materials based gas sensor. The adsorbent may behave like a donor or acceptor and thus, receive carrier from the host or inject carrier to the host, leading to the charge transfer between adsorbate and host 9 . The direction of charge transfer may reflect in 11 the band structure and finally on the electrical conductivity.…”

“…These studies suggest that defects, doping elements, strain, and electric field stimuli are also important parameters to enhance the selectivity/sensitivity of a particular gas 9,10,19,[11][12][13][14][15][16][17][18] . The sensing performance of gases is also explored by changing the chemical compositions of transition metal and chalcogen element or creating TMDCs monolayer heterostructures.…”

Sensing the polar molecules MH3 (M = N, P, or As) with a Janus NbTeSe monolayer

“…This is consistent with previous results of NH 3 adsorption on MoS 2 , MoSe 2 , MoSSe and WS 2 , where donor behavior is found. 17,24,27,[49][50][51][52] Taking WS 2 as an example, the sensing of NH 3 was experimentally demonstrated by Huo et al using WS 2 -FET (Field Effect Transistor) device, in which the channel electron density shows the electron transfer from NH 3 to the substrate WS 2 layer. 52 Specifically, for NbTeSe the monolayer, the charge transfers are approximately 0.042 e, 0.043 e and 0.051 e from NH 3 , PH 3 , and AsH 3 to Se surface, respectively.…”

Environmentally hazardous gas sensing ability of MoS2-nanotubes: an insight from the electronic structure and transport properties

“…20 The adsorption power of MoS 2 monolayer was found to be enhanced by silver functionalization. 21 Transition metal (V, Nb, Ta, and Ni) doped MoS 2 monolayer additionally showed potential gas adsorption properties. 22,23 The effect of applied electric eld on gas sensing by MoS 2 monolayer has also been reported.…”