Motivated by the exceptional interest of researchers in two-dimensional nanostructures, the current study deals with the structural, electronic, optical, and gassensing properties of recently synthesized monolayer phosphorene. Van der Waals induced first-principles calculations were performed to study the binding mechanism of pristine and defected phosphorene towards the toxic gases PH 3 and AsH 3 . The preferential sites and orientations of these molecules on the phosphorene sheet were determined, and a detailed analysis of the adsorption energetics was performed. Both of the gas molecules interact weakly with the phosphorene sheet, with AsH 3 the binding was slightly stronger than PH 3 . The creation of defects such as monovacancies and divacancies in the phosphorene sheet was found to significantly enhance the adsorption mechanism. The adsorption energies of both PH 3 and AsH 3 improved by factors of four and three, respectively, as compared to their values on pristine phosphorene. The adsorption mechanism was further investigated by plotting the band structure and density of states. We also studied the optical properties and the static dielectric matrices of these nanostructures using density functional perturbation theory. Our findings showed that defected phosphorene with vacancies can be considered as an efficient sensor for toxic gases.

By using first-principles calculations based on density functional theory, we study the adsorption efficiency of a BC3 sheet for various gases, such as CO, CO2, NO, NO2, and NH3. The optimal adsorption position and orientation of these gas molecules on the BC3 surface is determined and the adsorption energies are calculated. Among the gas molecules, CO2 is predicted to be weakly adsorbed on the graphene-like BC3 sheet, whereas the NH3 gas molecule shows a strong interaction with the BC3 sheet. The charge transfer between the molecules and the sheet is discussed in terms of Bader charge analysis and density of states. The calculated work function of BC3 in the presence of CO, CO2, and NO is greater than that of a bare BC3 sheet. The decrease in the work function of BC3 sheets in the presence of NO2 and NH3 further explains the affinity of the sheet towards the gas molecules. The energy gap of the BC3 sheets is sensitive to the adsorption of the gas molecules, which implies possible future applications in gas sensors.

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