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 is investigated using the density functional theory. Three types of defects (i) molybdenum vacancy, (ii) selenium vacancy, and (iii) sulfur/selenium vacancy are considered and their formation energy is computed to predict the stability. We noticed that selenium vacancy is the most stable among other defects. The maximum adsorption energy for H 2 S, NH 3 , NO 2 and NO molecules on pristine Janus MoSSe monolayer are ~ −0.156 eV, −0.203 eV, −0.252 eV, and −0.117 eV, respectively. 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 ~ −3.360 eV and −3.404 eV 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, 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. • The higher adsorption energy of NH 3 and NO 2 in S/Se V defect included monolayer may provide an efficient sensing platform. • Se V and S/Se V defects exhibit chemisorption for NO, whereas dissociation of NO 2 in oxygen and doping with NO adsorption. • NH 3 and H 2 S molecules have physisorption for pristine and defects included monolayers. • The onset of 1μ B magnetic moment is noticed after the adsorption of NO 2 and NO molecules.