Influence of the defect of activated carbon surface on cigarette smoke components adsorption: A DFT study

Density functional theory (DFT) was employed to systematically investigate the adsorption behaviors of CO, N₂O, nicotine, and phenol on complete and defective activated carbon surfaces. Structural optimizations and frequency analyses of calculation configurations were performed at the B3LYP/def2svp level, while single-point energy calculations utilized the B3LYP/def2tzvp basis set. The study revealed that defective carbon surfaces exhibited significantly higher adsorption capacities than the pristine counterparts, as evidenced by lower adsorption energies for all target molecules. To elucidate the underlying mechanisms, wave function analyses, Mayer bond order, electrostatic potential, Frontier molecular orbital, and Hirshfeld atomic charges were conducted. These investigations demonstrated that surface defects enhance local electronegativity and chemical reactivity at adsorption sites, facilitating stronger interactions with polar constituents of cigarette smoke. Specifically, defect-induced electron redistribution promoted charge transfer and orbital hybridization, critical for the chemisorption of toxicants. This theoretical framework advances the understanding of structure-activity relationships in carbon-based adsorbents, offering strategic insights for designing high-performance materials to mitigate hazardous components in tobacco smoke.