A comparative study of NH3 and H2S sensing performance on monolayer nanosheets through first-principle studies

This study investigates the sensing of H2S and NH3 over 2D nanosheets, namely graphene (GRA), boron nitride (BN), silicon carbide (SiC) and boron carbon nitride (BCN), using the first principle density functional theory. A CAM-B3LYP/6-31 G level of theory was used for all the computations and evaluation of the geometric and electronic properties. The optimized clusters indicated the chemisorption between the gas molecules and the SiC nanosheet. The Fourier transform infrared (FTIR) spectra were obtained to study the N-H and S-H shifts in the post-adsorption clusters. Based on the magnitude of the computed adsorption energies, SiC (-0.61 eV for the H2S cluster and -1.21 eV for the NH3 cluster) was found to adsorb both the gas molecules most effectively. The electrostatic potential maps and the molecular orbitals' distribution were studied to investigate the electronic properties. The analysis showed that the adsorption of H2S and NH3 over GRA, BN, and BCN was physical, whereas, on SiC, nanosheet chemisorption was observed. Atom-In-Molecule (AIM) analysis was carried out to account for the possible weak interactions. The study concluded that the SiC nanosheet was the most suitable for the adsorption of H2S and NH3 gases.