Aluminium phosphide (Al₁₂P₁₂) nanocage as a potential sensor for volatile organic compounds: A DFT study

The efficacy of aluminium phosphide (Al₁₂P₁₂) nanocage toward sensing methanol (MeOH) and ethanol (EtOH) volatile organic compounds (VOCs) was herein thoroughly elucidated utilizing various density functional theory (DFT) computations. In this perspective, MeOH⋯ and EtOH⋯Al₁₂P₁₂ complexes were investigated within all plausible configurations. According to the energetic features, the EtOH⋯Al₁₂P₁₂ complexes exhibited larger negative values of adsorption and interaction energies with values up to -27.23 and -32.84 kcal mol^-1, respectively, in comparison to the MeOH⋯Al₁₂P₁₂ complexes. Based on the symmetry-adapted perturbation theory (SAPT) results, the electrostatic forces were pinpointed as the predominant component beyond the adsorption process within the preferable MeOH⋯ and EtOH⋯Al₁₂P₁₂ complexes. The findings of the noncovalent interaction (NCI) index and quantum theory of atoms in molecules (QTAIM) outlined the closed-shell nature of the interactions within the studied complexes. Substantial variations were found in the molecular orbitals distribution patterns of MeOH/EtOH molecules and Al₁₂P₁₂ nanocage, outlining the occurrence of the adsorption process within the complexes under investigation. Thermodynamic parameters were denoted with negative values, demonstrating the spontaneous exothermic nature of the most favorable complexes. New energy states were observed within the extracted density of states plots, confirming the impact of adsorbing MeOH and EtOH molecules on the electronic properties of the Al₁₂P₁₂ nanocage. The appearance of additional peaks in Infrared Radiation (IR) and Raman spectra revealed the apparent effect of the adsorption process on the features of the utilized sensor. The emerging results declared the potential uses of Al₁₂P₁₂ nanocage as a promising candidate for sensing VOCs, particularly MeOH and EtOH.