Hydrogen storage capacity of Al, Ca, Mg, Ni, and Zn decorated phosphorus-doped graphene: Insight from theoretical calculations

In this work, adsorption of molecular hydrogen on five different metals: Aluminum, Calcium, Magnesium, Nickel and Zinc decorated phosphorus-doped graphene have been investigated using density functional theory (DFT) computation at the PBE0-D3BJ/def2svp method. From literature reviews, phosphorus doped graphene are potential candidates for hydrogen storage. Herein, theoretical investigation on the changes in structural and electronic properties of the studied materials was conducted. Natural bond orbital (NBO) analysis was employed to study the intermolecular and intra-molecular interactions arising from chemical bonds in the studied systems. In addition, the density of states (DOS) plots shows notable individual orbital contribution and hybridization between the decorated metals and the phosphorus-doped graphene which is also responsible for the adsorption of hydrogen. Based on the frontier molecular orbital analysis, results indicates that Al and Ni surfaces possess excellent structural and electronic properties with lower values of chemical hardness and ionization with adsorption energy values of 1.924eV and 1.236eV obtained for both surfaces potential indicating better conductivity and excellent H2 adsorption potential. The obtained results shows the suitability of the Al and Ni decorated phosphorus-doped graphene for hydrogen storage.