Theoretical investigation of NH3 and NO2 affinity towards Boron-Nitride Nanosheet: A DFT Study

Abstract

Two-dimensional (2D) nanosheets have been widely explored for sensing toxic gases by investigating structural and electronic properties. However, the optical investigation could be an alternative approach to address the sensing capability of the nanosheets. In the present work, the electronic and optical investigation is performed using density functional theory (DFT) to find out the sensitivity of boron-nitride nanosheet (BNNS) towards NH3 and NO2 gas molecules. Electronic investigation suggests a weak binding of NH3 and NO2 with the 2D sheet, with appreciable changes in the BNNS electronic density of state (DOS) on NO2 interaction. NH3 interaction could not affect the BNNS DOS except for lowering of band dispersion graph across the Fermi level. NO2 interaction brings a noticeable change in spectra, primarily red-shift. Based on this information, tuning is also observed in different optical descriptors, i.e., dielectric constant, refractive index, and extinction coefficient of NO2 interacted BNNS. All these findings advocate sensitivity toward the gas molecule of the 2D sheet could be realized from the optical frame. Finding NH3 and NO2 affinity of Boron-Nitride Nanosheet Through Optical Spectrum: A DFT Study. The calculations are performed in the framework of density functional theory (DFT) using Troullier Martins’s norm-conserving pseudo-potential. The NO2 interacted BNNS shows the optical spectra get red-shifted, and the primary reason is the available NO2 molecular state below the fermi level as shown in PDOS analysis. The present investigation predicted an almost similar ε2 spectra pattern of BNNS and NH3-BNNS except in shallow region 7eV-10eV; a weak absorption band appeared in this region after NH3 absorption. The main concern for this deviation is the electronic transitions taken from the valance N-p-state of NH3 to the conduction band (primarily π* in nature) of BNNS.