Spin-polarized Density Functional Theory on Iron-decorated Planar Aluminene Systems for Hydrogen Storage

Abstract

The storage of hydrogen gas produced from different processes such as biomass gasification is one of the challenges towards hydrogen economy to achieve a sustainable clean energy. Different 2D materials are being explored for a suitable storage such as aluminene due to its large surface area. In this work, we investigated using spin polarized density functional theory the adsorption of iron on the different sites of planar aluminene: top, bridge and hollow. Results showed that iron can be adsorbed on aluminene on all sites favoring the hollow site with a binding energy of -7.83 eV. The charge density differences show charge transfers from the aluminum atom towards the iron atoms indicating chemical bond. Results showed net magnetization based on the density of states which can be utilize for reversible hydrogen gas induced magnetization switching for hydrogen storage. Hydrogen is physisorped on the Fe atoms located at the top and bridge site of aluminene without energy barrier, while hydrogen is chemisorped on Fe atom located at the hollow site with an energy barrier of 0.063 eV. These results are indicative that Fe-decorated aluminene systems can be a good hydrogen storage material.