The analysis of electronic structures, adsorption properties, NBO, QTAIM and NMR parameters of the adsorbed hydrogen sulfide on various sites of the outer surface of aluminum phosphide nanotube: a DFT study

Density functional theory (DFT) calculations at the B3LYP/6-31G* level are performed to investigate the adsorption properties and quantum molecular descriptors of H2S adsorbed on the external surface of (6,0) single-walled aluminum phosphide nanotube (AlPNT). The vibrational frequencies and physical properties such as dipole moment, chemical potential, chemical hardness and chemical electrophilicity of all studied configurations have been systematically explored. Also, the interaction of H2S gas and AlPNT on the basis of five reactivity descriptors such as the overall stabilization energy (Delta E-SE(AB)), the individual energy change of the acceptor (AEA(3)), the individual energy change of donor (Delta E-B(A)), the global electrophilicity difference of AlPNT and H2S gas (Delta w) and charge transfer (AN) has been explained. All adsorptions are electronically harmless processes and venial impacts on the energy gap of the AlP nanotube. The natural bond orbital calculations are done to derive natural atomic orbital occupancies. The H2S molecule physisorbed on the surface of pristine AlP nanotube with adsorption energy of about -20 kJ/mol. The AIM theory has been also used to examine the properties of the bond critical points: their electron densities and Laplacians. The adsorption energy of H2S molecule is not so large to hinder the recovery of the AlPNT, and therefore, the sensor will possess short recovery times. Electronic structures of pristine AlPNT and adsorbed H2S gas AlPNT models are examined by DFT calculations of chemical shielding (CS) parameters of Al-27 and P-31 atoms. The isotropic and anisotropic CS parameters are divided into layers based on the detection of similar electronic environments by the atomic sites of each layer.