Environmental Remediation of Methyl Bromide Using Alkali Metal–Encapsulated Al ₁₂ N ₁₂ Nanocages: A DFT Insight

Methyl bromide (CH 3 Br) is a serious environmental contaminant due to its strong ozone‐depleting effects and toxicity, which threaten both atmospheric health and public safety. Therefore, developing quick, accessible, and effective methods for detecting and removing this pollutant is essential for successful environmental cleanup. In this study, we examined CH 3 Br removal using alkali metal (Li, Na, and K)–encapsulated aluminum nitride nanocages (Al 12 N 12 ). Density functional theory (DFT) at the B3LYP(D4)/def2‐SVP level was used to analyze how CH 3 Br adsorbs onto both pristine and encapsulated Al 12 N 12 nanocages. The encapsulated structures are found to be chemically stable and show a significant increase in adsorption ability compared to the bare cage. The Li@Al 12 N 12 structure demonstrated the strongest adsorption strength (−92.74 kJ/mol), greatly exceeding that of pristine Al 12 N 12 (−76.23 kJ/mol) and other encapsulated variants. A marked decrease in the HOMO–LUMO bandgap was observed in the CH3Br/Li@Al 12 N 12 complex (down to 1.590 eV from 4.077 eV in Al 12 N 12 ), implying improved conductivity. Additionally, these interactions are spontaneous and exothermic, with Li@Al 12 N 12 displaying the most negative Gibbs free energy (−85.96 kJ/mol) and enthalpy, indicating the most stable adsorption. Topological and reduced density gradient (RDG) analyses confirm the presence of partially covalent Al···Br interactions, which enhance the stability of the complex. In conclusion, Li@Al 12 N 12 appears to be the most promising for developing filtration and advanced removal technologies for environmental remediation.