The adsorption of acetone, dichlorobenzene, dichloropbentane, nitrotoluene, trinitrotoluene triethylamine, tetrahydrofuran and methanol was investigated on graphene and MoS2 using density functional theory (DFT). The calculation results of adsorption geometries show great similarities for both surfaces. To understand the chemical sensing characteristics of these two dimensional materials, we calculated energetics, electronic charge densities and charge transfer upon adsorption of these large molecules. We find that all of these molecules physisorb on both graphene and MoS2 and to correctly predict their binding energies it is important to include van der Waals corrections to the density functional. The characteristic of charge transfer upon adsorption of molecule on a simplified model of free-standing films do not offer the explanation of large differences in the sensing capabilities of graphene and MoS2 that has been observed in experiments. We find the inclusion of SiO2 substrate is essential to understand the differences between graphene and MoS2 surfaces. Both graphene and MoS2 show a p-type doping characteristics on SiO2 substrate, however, a large charge transfer among adsorbed MoS2 surface is found compared to graphene. This can very well explain to large selectivity of MoS2 based sensors towards studied molecules when compared to graphene based sensor.

DFT study on the origins of high selectivity of single layer of MoS<sub>2</sub> over graphene for gas sensing

248th National Meeting (2014)

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DFT study on the origins of high selectivity of single layer of MoS2 over graphene for gas sensing

DFT study on the origins of high selectivity of single layer of MoS₂ over graphene for gas sensing