First principles investigation of hydrogen storage in intermetallic systems

Download
2007
Kınacı, Alper
The design and production of efficient metal-hydrides for hydrogen storage is a long standing subject. Over the years, many different types of intermetallic hydride systems were studied and some of them came out to be operable. However, none of them meet all the storage criteria perfectly. In this study, total energies, hydrogen storage capacity and stability of AB (A = Al, Be, Cu, Fe, Ni, Sb, V and B = Ti) type intermetallics were investigated with the goal of spotting a potential hydrogen storage material. The relation between thermodynamic properties and the atomic and the electronic structure of hydrides are also pointed out. For this task, first principles pseudopotential method within the generalized gradient approximation (GGA) to density functional theory (DFT) was used. Calculations correctly predict experimentally determined structures except for CuTiH. Moreover, the atomic and cell parameter were found within the allowable error interval for DFT. In CuTi intermetallic, a structure having considerably lower formation energy than experimentally found mono-hydride was determined. This contradiction may be due to metastability of the experimental phase and high activation energy for the hydrogen movement in the system. It was found that AlTi and SbTi are not suitable candidates for hydrogen storage since their hydrides are too unstable. For the other intermetallic systems, the stability of the hydrides decreases in the order of VTi, CuTi, NiTi, BeTi, FeTi. For VTi, FeTi and NiTi, a change in metallic coordination around hydrogen from octahedron to tetrahedron is predicted when tetra-hydride (MTiH4) is formed. Additionally, at this composition, FeTi and NiTi have hydride structures with positive but near-zero formation energy which may be produced with appropriate alteration in chemical makeup or storage parameters. VTi is a promising intermetallic by means of storage capacity in that even VTiH6 is found to have negative formation energy but the hydrides are too stable which can be a problem during hydrogen desorption.

Suggestions

Surface energy and excess charge in (1x2)-reconstructed rutile TiO2(110) from DFT plus U calculations
Unal, Hatice; METE, ERSEN; Ellialtıoğlu, Süleyman Şinasi (2011-09-09)
Physically reasonable electronic structures of reconstructed rutile TiO2(110)-(1x2) surfaces were studied using density functional theory (DFT) supplemented with Hubbard U on-site Coulomb repulsion acting on the d electrons, the so called DFT + U approach. Two leading reconstruction models proposed by Onishi and Iwasawa [Surf. Sci. Lett. 313, 783 (1994)] and Park and coworkers [Phys. Rev. B 75, 245415 (2007)] were compared in terms of their thermodynamic stabilities.
Nickel extraction from Gördes laterites by hydrochloric acid leaching
Göveli, Ahmet; Atalay, M Ümit; Department of Mining Engineering (2006)
Leaching is the most widely used process for extraction of nickel metal from lateritic ores. In this study, nickel extraction from Manisa-Gördes region laterites by hydrochloric acid leaching is aimed. The mineralogical analysis of sample showed that hematite, goethite, dolomite, quartz and smectite are the main minerals in the ore. Attrition scrubbing, cycloning and magnetic separation with permroll were used as preconcentration processes but results were unsatisfactory. HCl leaching experiments were condu...
Kinetic approach for the purification of nucleotides with magnetic separation
Tural, Servet; Tural, Bilsen; Ece, Mehmet Sakir; Yetkin, Evren; Özkan, Necati (2014-11-01)
The isolation of beta-nicotinamide adenine dinucleotide is of great importance since it is widely used in different scientific and technologic fields such as biofuel cells, sensor technology, and hydrogen production. In order to isolate beta-nicotinamide adenine dinucleotide, first 3-aminophenyboronic acid functionalized magnetic nanoparticles were prepared to serve as a magnetic solid support and subsequently they were used for reversible adsorption/desorption of beta-nicotinamide adenine dinucleotide in a...
Electronic properties of transition metal oxides
Mete, Ersen; Ellialtıoğlu, Süleyman Şinasi; Department of Physics (2003)
Transition metal oxides constitute a large class of materials with variety of very interesting properties and important technological utility. A subset with perovskite structure has been the subject matter of the current theoretical investigation with an emphasis on their electronic and structural behavior. An analytical and a computational method are used to calculate physical entities like lattice parameters, bulk moduli, band structures, density of electronic states and charge density distributions for v...
Novel investigation of pyrolysis mechanisms and kinetics for functional groups in biomass matrix
Liu, Ruijia; Liu, Guijian; Yousaf, Balal; Niu, Zhiyuan; Abbas, Qumber (2022-01-01)
Biomass, as a renewable and sustainable energy resource, can be converted into environmentally friendly and practically valuable biofuels and chemical materials via pyrolysis. However, the process optimization and pyrolysis efficiency are restricted by the limited perception of the complicated mechanisms and kinetics for biomass pyrolysis. Here, to establish an in-depth mechanism model for biomass pyrolysis, we presented a novel investigation for the thermal evolutions and pyrolysis kinetics of the function...
Citation Formats
A. Kınacı, “First principles investigation of hydrogen storage in intermetallic systems,” M.S. - Master of Science, Middle East Technical University, 2007.