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

Abstract

Gas sensing mechanism of H 2 S, NH 3 , NO 2 and NO toxic gases on transition metal dichalcogenides based Janus MoSSe monolayers are investigated using the density functional theory. The pristine and defect included MoSSe layers are considered as a host material for adsorption study. Three types of defects (i) molybdenum vacancy, (ii) selenium vacancy, and (iii) sulfur/selenium vacancy are studied to understand their impact on electronic properties and sensing of these gas molecules. The formation energy is computed to predict the stability of these defects and noticed that selenium vacancy is the most stable among other defects. The adsorption of gas molecules is evaluated in terms of adsorption energy, vertical height, charge difference density, Bader charge analysis, electronic and magnetic properties. The maximum adsorption energy for H 2 S, NH 3 , NO 2 and NO molecules on pristine Janus MoSSe monolayer are ~ -0.156eV, -0.203eV, -0.252eV, and -0.117eV, respectively. Selenium and sulfur/selenium defects significantly improve the sensing of the gas molecules. NO 2 gas molecule dissociates and forms oxygen doped NO adsorption in selenium and sulfur/selenium defect included MoSSe Janus monolayer. The adsorption energy values are ~ -3.360eV and -3.404eV for Se and S/Se defects included MoSSe layer, respectively. Further, the adsorption of NO 2 molecule induced about 1µ B magnetic moment. In contrast, NO molecule showed chemisorption on the surface of the selenium and sulfur/selenium defect included Janus MoSSe monolayers, whereas H 2 S and NH 3 molecules showed physisorption with their adsorption energies in the range of -0.146 to -0.238 eV and -0.140 to -0.281 eV, respectively. The adsorption of H 2 S, NH 3 , NO 2 and NO molecule on the pristine and defected monolayers suggest that selenium and sulfur/selenium vacancy defects are more prominent for NO 2 and NO gas molecule adsorption.

Transition from Schottky to Ohmic contacts in Janus MoSSe/germanene heterostructures

“…10 On the other hand, the intrinsic dipole of MoSSe (structural symmetry of MoS 2 is broken) modifies the electronic properties. 11 A number of theoretical studies have shown that two-dimensional Janus materials perform well in gas sensors, 12,13 photocatalytic water splitting, [14][15][16] field-effect transistors, 17 and solar cells. 18,19 However, practical use of MoSSe in a device will require a contact with metal electrodes to enable injection of carriers.…”

Intrinsic defect engineered Janus MoSSe sheet as a promising photocatalyst for water splitting

“…43 Chaurasiya et al have found that intrinsic defects can effectively alter the adsorption behaviors of NO 2 , NO, and NH 3 on Janus MoSSe sheet. 44 However, the detailed role of the intrinsic defects on introducing the adsorption state and enhancing the photoreaction of water is still unknown.…”

Highly Sensitive Gas Sensing Material for Environmentally Toxic Gases Based on Janus NbSeTe Monolayer

“…From this point of view, Janus monolayer has excellent potential candidates to realize superior sensitivity without gate bias. Some of the work has been reported on various gas molecules detection for gas sensing devices [ 35 , 43 , 44 , 45 , 46 , 47 , 48 , 49 ]. Still, there is a need for a better understanding of various gas sensing properties of the Janus monolayer.…”