An ab initio study of sensing applications of MoB2 monolayer: a potential gas sensor

Abstract

Using first principles density functional theory, we have studied the interaction mechanism of NO₂ and SO₂ gas molecules on an MoB₂ monolayer, for gas sensing applications. The selectivity for a particular gas by the sensor has been analyzed through electronic structure calculations and adsorption studies. The calculations have been performed by considering the fact that the MoB₂ monolayer as a sensing material encounters a change in its electrical properties, when gas molecules with different orientations get adsorbed on the surface. From the density of states study, we find better selectivity for NO₂ as compared to SO₂, as the latter leaves the electronic structure of the sensing material unaffected. Further, the adsorption curves support the above fact as the larger value of adsorption energy (E_ad ∼ −1 eV) for NO₂ indicates stronger adsorption. The chemisorptive nature for NO₂, in contrast with the relatively weaker physisorption for SO₂, additionally supports the fact that NO₂ gas has a better perspective for MoB₂ sensor application. Charge density plots for each case are in good agreement with the above conclusions. The faster recovery time attributes the MoB₂ monolayer better as a sensor material for NO₂ interaction.