Electronic structure and adsorption behavior of 2PANI with selected gases: A DFT approach

This study examines the adsorption properties of C2H4, F2, HCl, and H2S gases on 2PANI using density functional theory (B3LYP/6-311++G(d,p)). Adsorption energies follow the order: 2PANI-HCl > 2PANI-H2S > 2PANI-C2H4 > 2PANI-F2 including the BSSE corrections. Geometry optimizations and topological analyses (electrostatic potential, localized orbital locator and electron localization function) were performed using Multiwfn software. Mulliken charge analysis assessed the sensing potential of 2PANI for each gas. Time-dependent DFT was used to analyze molecular orbitals, reactivity indices, density of states, and UV-Vis spectra, revealing red or blue shifts depending on the gas type. The results confirm that C2H4, F2, HCl, and H2S can be physically adsorbed onto 2PANI. The recovery time and conductivity were evaluated to determine gas sensitivity performance.