Ab initio design of novel magnesium alloys for hydrogen storage

Download

index.pdf

Date

2008

Author

Keçik, Deniz

Metadata

Show full item record

Item Usage Stats

240
views

46
downloads

A candidate hydrogen storing material should have high storage capacity and fast dehydrogenation kinetics. On this basis, magnesium hydride (MgH2) is an outstanding compound with 7.66 wt % storage capacity, despite its slow dehydriding kinetics and high desorption temperature. Therefore in this study, bulk and surface alloys of Mg with improved hydrogen desorption characteristics were investigated. In this respect, formation energies of alloyed bulk MgH2 as well as the adsorption energies on alloyed magnesium (Mg) and MgH2 surface structures were calculated by total energy pseudopotential methods. Furthermore, the effect of substitutionally placed dopants on the dissociation of hydrogen molecule (H2) at the surface of Mg was studied via Molecular Dynamics (MD). The results displayed that 31 out of 32 selected dopants contributed to the decrease in formation energy of MgH2 within a range of ~ 37 kJ/mol-H2 where only Sr did not exhibit any such effect. The most favorable elements in this respect came out to be; P, K, Tl, Si, Sn, Ag, Pb, Au, Na, v Mo, Ge and In. Afterwards, a systematical study within adsorption characteristics of hydrogen on alloyed Mg surfaces (via dynamic calculations) as well as calculations regarding adsorption energies of the impurity elements were performed. Accordingly, Mo and Ni yielded lower adsorption energies; -9.2626 and -5.2995 eV for substitutionally alloyed surfaces, respectively. MD simulations presented that Co is found to have a splitting effect on H2 in 50 fs, where the first hydrogen atom is immediately adsorbed on Mg substrate. Finally, charge density distributions were realized to verify the distinguished effects of most 3d and 4d transition metals in terms of their catalyzer effects.

Subject Keywords

Metallurgical analysis.

URI

http://etd.lib.metu.edu.tr/upload/12609722/index.pdf
https://hdl.handle.net/11511/17728

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Ab initio alloying of Mg for hydrogen storage Kecik, Deniz; Aydınol, Mehmet Kadri (null; 2008-12-01) A candidate hydrogen storing material should have high storage capacity and fast dehydrogenation kinetics. On this basis, magnesium hydride (MgH 2) is an outstanding compound with 7.6 wt % storage capacity, despite its slow dehydriding kinetics and high desorption temperature. Therefore in this study, formation energies of alloyed bulk MgH2, adsorption energies on alloyed magnesium (Mg) and MgH2 surface structures were calculated by total energy pseudopotential methods. Also, the effect of substitutionally ...
Temel prensipler yöntemiyle magnezyum ve demir - titanyum hidrürlerinin modellenmesi, tasarımı ve üretimi Aydınol, Kadri M.; Tan, Serdar; Akyıldız, Hasan; Kınacı, Alper; Şen, Fatih(2008) A candidate hydrogen storing material should have high storage capacity and fast dehydrogenation kinetics. On this basis, magnesium hydride (MgH2) is an outstanding compound with 7.66 wt % storage capacity, despite its slow dehydriding kinetics and high desorption temperature. Therefore in this study, bulk and surface alloys of Mg with improved hydrogen desorption characteristics were investigated. In this respect, formation energies of alloyed bulk MgH2 as well as the adsorption energies on alloyed magnesi...
Combinatorial study of hydrogen storage alloys Ölmez, Rabia; Öztürk, Tayfur; Department of Metallurgical and Materials Engineering (2009) A combinatorial study was carried out for hydrogen storage alloys which involve processes similar to those normally used in their fabrication. The study utilized a single sample of combined elemental (or compound) powders which were milled and consolidated into a bulk form and subsequently deformed to heavy strains. Material library was obtained in a post annealing treatment carried out at elevated temperatures which brings about solid state reactions between the powders yielding equilibrium phases in the r...
Catalytic hydrolysis of hydrazine borane for chemical hydrogen storage: Highly efficient and fast hydrogen generation system at room temperature Karahan, Senem; Zahmakiran, Mehmet; Özkar, Saim (2011-04-01) There has been rapidly growing interest for materials suitable to store hydrogen in solid state for transportation of hydrogen that requires materials with high volumetric and gravimetric storage capacity. B-N compounds such as ammonia-triborane, ammonia-borane and amine-borane adducts are well suited for this purpose due to their light weight, high gravimetric hydrogen storage capacity and inclination for bearing protic (N-H) and hydridic (B-H) hydrogens. In addition to them, more recent study [261 has sho...
Production and characterization of alumina fiber reinforced squeeze cast aluminum alloy matrix composites Keleş, Özgür; Kalkanlı, Ali; Department of Metallurgical and Materials Engineering (2008) The aim of the present study was to investigate the effects of different levels of Saffil alumina fiber addition, magnesium content in aluminum alloy matrix and casting temperature on the mechanical behavior, microstructure and physical properties of short fiber reinforced aluminum matrix composites. The main alloying element silicon was kept constant at 10 wt%. Magnesium contents were selected as 0.3 wt% and 1 wt%. Saffil alumina fiber preforms varied from 10 to 30 vol%. The casting temperatures were fixed...

Citation Formats

D. Keçik, “Ab initio design of novel magnesium alloys for hydrogen storage,” M.S. - Master of Science, Middle East Technical University, 2008.