A Density functional theory investigation for solid state hydrogen storage materials

Gencer, Ayşenur
The world’s energy demand is increasing with the population growth and technology development. In addition, the electronic devices are an essential part of the daily life that require portable energy sources. Therefore, energy storage is necessary in order to store energy from the renewable energy sources and also provide portable energy sources for electronic devices. Hydrogen being the most abundant element in the world, is a good energy carrier with high energy density. Also, hydrogen does not release greenhouse gases that contribute to the global warming. In addition to these properties, it can be stored in metals with physical or chemical bonds that allows an interest to the solid state hydrogen storage materials which are considered as a promising solution with effective and safe hydrogen storage. For these reasons, its use in fuel cells is emerging. Considering the cost and difficulties of experimental studies for determination of new materials to be used in hydrogen storage, theoretical studies have became a tool for experimental studies. The most important method of theoretical studies is Density Functional Theory (DFT). This method is popular in recent years because it can be used without depending on any experimental data. In this study, the first principles calculations have been performed to investigate the hydrogen storage properties of perovskite materials that could be a possible candidate material group for the solid state hydrogen storage method due to having stability and ceramic nature. The studied perovskite materials are divided into three groups as perovskite materials with BaXO3 (X = Sc or Y) and XTiO3 (X = Mg or Ca) compounds, anti-perovskite materials with Ca3XH (X= C or N) compounds and perovskite type hydrides with XNiH3 (X = Li, Na or K) compounds. The structural, mechanic, electronic, thermodynamic and lattice dynamic properties of these materials have been examined by using the Vienna Ab-initio Simulation Package (VASP) based on DFT. The results have been compared with the available results from the literature and it has been found that the results are consistent with the literature. Furthermore, the hydrogen doping studies to BaXO3, XTiO3 and Ca3XH compounds have been performed and the gravimetric hydrogen storage capacities and the hydrogen desorption temperatures have been obtained to reveal the properties of these materials for the hydrogen storage applications.
Citation Formats
A. Gencer, “A Density functional theory investigation for solid state hydrogen storage materials,” Thesis (Ph.D.) -- Graduate School of Natural and Applied Sciences. Physics., Middle East Technical University, 2018.