Abstract
Nanoclusters such as Al12N12 have received increased attention due to their diverse applications in the fields of optoelectronics and energy storage. In this paper, we have investigated a series of alkaline earth metal (AEM)-encapsulated Al12N12 nanoclusters for hydrogen adsorption. Thermodynamic adsorption parameters, optical and nonlinear optical properties were investigated using density functional theory (DFT) at the B3LYP/6-31G(d,p) level of theory. Encapsulation of AEMs (Be, Mg and Ca) is an effective strategy to improve the NLO reaction and thermodynamic and adsorption properties of Al12N12 nanoclusters. The adsorption energies ranging from -26.57 kJ/mol to -213.33 kJ/mol for the three guests (Be, Mg and Ca) capsulated Al12N12 nanoclusters are observed. The adsorption energy is affected by the size of the nanocage. Therefore, Ca- and Mg-encapsulated cages show higher values of adsorption energy. Overall, an increase in adsorption energy (E-ad = -31.91 kJ/mol to -91.06 kJ/mol) is observed for (Be, Mg and Ca) encapsulated Al12N12 nanoclusters compared to untreated Al12N12 and H-2-Al12N12 cages. Moreover, adsorption of hydrogen on AEMs encapsulated in Al12N12 leads to a decrease in the HOMO-LUMO energy gap with an enhancement of linear and nonlinear hyperpolarizability. All hydrogen-adsorbed AEMs Al12N12 nanocages exhibit large alpha(total) and beta o values, suggesting that these systems are potential candidates for optical materials. Various geometrical parameters such as frontier molecular orbitals (FMOs), partial density of states, global quantum descriptor of reactivity, natural bond orbital testing and molecular electrostatic strength analyses were performed to investigate the thermodynamic stability of all the studied systems. The results obtained confirmed that the designed systems are suitable for hydrogen storage. Therefore, we recommend that these systems be investigated for their hydrogen storage and optical properties.