Investigation of Electronic and Topological Properties of Magnesium-coated Boron Fullerenes and Their Interaction with Hydrogen Molecule

Various nanostructures have been widely investigated as alternative materials for hydrogen storage using experimental and computational techniques. Combination of boron fullerenes with metals such as magnesium can be used as hydrogen storage materials. In this research, the electronic properties and topology of magnesium-doped boron fullerenes and their interaction with H2 for hydrogen storage are investigated using density functional theory. By density functional calculations with B3LYP/6-31G//M062X/6-31G** method, the structures of B80, Mg12B80, Mg20B80 and Mg30B80 were optimized and the total energy of each of them are calculated. The charge transfer from Mg to B atoms creates an electric field around Mg atoms with a positive charge. When hydrogen molecules approach the system, the hydrogen molecules become polarized and they are adsorbed to these boron fullerenes doped with Mg atoms. Adding one hydrogen molecule to the B80, Mg12B80, Mg20B80 and Mg30B80 structures, adsorption energies, electronic properties and some molecular descriptors were calculated. The results showed that Mg12B80 has the lowest gap energy (ΔEH-L), the lowest hardness (ƞ), and the highest adsorption energy, which indicates the reactivity and the hydrogen storage ability of this structure is higher than B80, Mg20B80 and Mg30B80.