Investigating the electronic structure and adsorption of OCN⁻ and CN⁻ on Si₁₂C₁₂ Fullerene-like cages using DFT and MD simulations

The adsorption behavior of the toxic molecules OCN⁻ and CN⁻ onto Si₁₂C₁₂ fullerene-like cages was performed using density functional theory (DFT) calculations with the B3LYP and PBE functionals and a 6-311 + G** basis set, in both vacuum and aqueous phases (PCM model). Strong adsorption of OCN⁻ (nitrogen head) and CN⁻ (carbon head) to the cage surface results from covalent bonding and significant charge transfer from the fullerene-like cage to the anions in both phases. These adsorption processes, involving OCN⁻ via its nitrogen head and CN⁻ via its carbon head, were both spontaneous and exothermic, as indicated by the calculated adsorption energies and thermodynamic parameters. MD simulations show rapid OCN⁻ covalent bonding to the Si₁₂C₁₂ cage, followed by equilibration within 5 ps. The OCN⁻ exhibits higher mobility than the cage, as indicated by MSD analysis. This dynamic interaction, revealed by g(r) and MSD data, suggests a surface adsorption process. The impacts of OCN⁻ and CN⁻ interaction with the fullerene-like cage surface were assessed using infrared (IR) absorption spectroscopy. The photoelectron spectrum of OCN⁻ and CN⁻ adsorption suggests interactions between the fullerene-like cage and these molecules, emphasizing the involvement of strongly bonded electrons in facilitating these interactions. Significantly, during the adsorption process, there was a notable orbital hybridization between anions and fullerenes, as evidenced by the calculated total density of states (TDOS). DFT calculations show that Si₁₂C₁₂ fullerene-like cage exhibits strong binding energies for OCN⁻ and CN⁻, suggesting its potential for highly efficient removal in environmental samples.