Substituted 2D Janus WSSe monolayers as efficient nanosensor toward toxic gases

The presence of inherent strain and electric field in the Janus transition metal dichalcogenide nanosheets widens their applications in nanodevices. The weak interactions between pristine Janus monolayers and gas molecules limit the applications of Janus sheets in gas sensing devices. However, tuning of structural and electronic properties by doping of foreign atoms in the lattice structure improves the gas sensing property of Janus WSSe monolayers. Herein, the superior gas sensing property of N, P, and As doped Janus WSSe monolayers for CO, NO, and HF gases has been studied using spin-polarized density functional theory. The binding energy analysis shows that the 3.12% doping of N, P, and As at S/Se sites is an exothermic process. New bands have been observed near the Fermi region in doped nanosheets. The simulations also reveal that doping improves the gas sensing properties of the doped sheets because of strong interactions between adsorbate and adsorbent. The interactions between gas molecules and doped WSSe monolayers are examined with the help of density of states plots. The uni-axial tensile strain tends to further improve the adsorption of CO on the nitrogen-doped WSSe nanosheet. Based on the present studies, it is evident that only 3.12% doping of foreign atoms makes WSSe Janus monolayers efficient material for CO, NO, and HF gas sensing without imposing external strain.