Computational insights into the electronic structure and adsorption properties of CN, CNCl, and NO2 on metal (Na, Zn, and Al,) doped fullerene surfaces

Abstract

The hazards of pollution are highlighted by gas exposure, and creating effective adsorbents is essential for maintaining clean air, the environment, and human health. In our study, employing the DFT/M062x/def2svp level of theory, the potentials of metal-doped (Na, Zn, and Al) fullerene surfaces as efficient adsorbents for CN, CNCl, and NO₂ gases were evaluated. Investigation revealed that the introduction of metal dopants has visible impacts on the structural and electronic properties of fullerene surfaces. Specifically, a slight increase in the bond length of C–C bonds, with protruded bonds forming between the doped atoms and carbon atoms, was observed. The obtained energy gap (Eg) demonstrated a consistent reduction across the doped surfaces, indicative of heightened sensitivity toward the gas analytes. C59Al exhibited a higher Eg (3.876 eV), while C59Zn displayed a lower value (3.103 eV) compared to C59Na. Topology analysis using the quantum theory of atoms in molecules (QTAIM) predicted non-covalent interactions between gas analytes and metal-doped fullerene surfaces, a finding that was further substantiated by the analysis of non-covalent interactions. Focusing on CN gas adsorption, distinct behaviors emerged, where C59Na exhibited strong adsorption (Eads = −2.67 eV), surpassing C59Al (−1.82 eV) and C59Zn (−0.64 eV). A similar trend was observed for CNCl and NO₂ gas adsorption, with C59Na consistently showing higher adsorption energies. This alignment was corroborated by frontier molecular orbital (FMO) and natural bond orbital (NBO) analyses. The results for dipole moment and recovery time emulated those of adsorption energy, emphasizing the stability and uniformity in adsorbed states. This collective evidence highlights the potential of doped surfaces to effectively adsorb specific gas molecules, offering insights into their applicability in gas sensing and environmental remediation.