First-principles study of adsorption and sensing properties of Re and Tc-doped gallium nitride nanotube (GaNNT) for oil-dissolved gases

In this study, the density functional theory (DFT) method at the B3LYP-GD3BJ/def2svp level of computation was employed to elucidate the adsorption properties of oil-dissolved gases; ethyl (C₂H₂), methane (CH₄), and hydrogen (H₂) gas molecule on pure, rhenium (Re), and technetium (Tc) doped GaNNT. The results of the frontier molecular orbitals shows that the doping of Re and Tc on GaNNT surface increases the conductive and sensitivity properties of the surfaces towards the adsorption of investigated gas molecules. The Re doped on GaNNT (Re@GaNNT) surface enhances the stabilization of the donor and acceptor orbitals before and after the adsorption of the considered gas molecules. The DOS of each of these materials is influenced by the presence of dopants Re and Tc. The Re and Tc atoms significantly influenced the energy level in the DOS for the surfaces and complexes. The adsorption of gas molecules on GaNNT and its doped counterparts were analyzed and compared by calculating the adsorption energy of each structure to obtain the most stable adsorption structures. We calculated the adsorption energies and found that CH₄ adsorbed positively in all systems, but H₂ adsorbed more effectively on GaNNT with an Eads of −0.008 eV. Positive values for weak adsorption are the outcome of other adsorptions. Additionally, all systems experienced substantial adsorptions following the complexation of C₂H₂. The equivalent Eads for C₂H₂GaNNT, C₂H₂Re@GaNNT, and C₂H₂Tc@GaNNT are –32.550 eV, –32.061 eV, and −31.685 eV, respectively. GaNNT, on the other hand, is believed to adsorb C₂H₂ better than other systems, with an Eads of 32.550 eV. GaNNT is a better adsorbent for C₂H₂ and H₂ with high and negative Eads, but it is inappropriate for CH4 sensing due to the weak adsorption and minimal conductivity change.