First principles investigation on H2 adsorption on the pristine 2-dimensional hexagonal aluminum

• Main Authors: Villagracia, Al Rey C., Ong, Hui Lin, David, Melanie Y., Arboleda, Nelson B., Jr.
• Format: text
• Published: Animo Repository 2019
• Subjects: Hydrogen; Green technology; Energy conservation; Aluminum; Crystal lattices; Atoms; Density functionals; Physics
• Online Access: https://animorepository.dlsu.edu.ph/faculty_research/3702; https://animorepository.dlsu.edu.ph/context/faculty_research/article/4704/type/native/viewcontent/012135.html
• Institution: De La Salle University

Lightweight hydrogen storage with high storage capacity is one of the challenges in pursuing a hydrogen economy as a source of clean energy. Aluminum has been proposed as a material for storage and production of hydrogen. Recent theoretical studies have established the feasibility of 2D hexagonal lattice structure aluminum. In this study theoretical investigation on 2D h-aluminum was performed employing density functional theory to study the energetics of hydrogen molecule and 2D h-aluminum system. Hydrogen molecule on top, hollow and bridge sites of hexagonal lattice were geometrically optimized to determine if hydrogen molecule would dissociate or adsorbed as a molecule. Results showed that hydrogen molecule can be physisorped mainly in the bridge site (-0.463 eV) at a distance of 3.1 Å, while it can dissociate at the top site with an activation energy of 1.51 eV. Electron density difference shows transfer of 0.60e- from hydrogen atoms to the aluminum atoms. Density of states showed broadening of energy levels and their general shift towards lower energies, and alignment of the orbitals showing sp hybridization. Results of this study can be used in further investigation on doped or decorated systems of 2D h-aluminum. © Published under licence by IOP Publishing Ltd.