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Atomistic Modelling of Materials for Clean Energy Applications: hydrogen generation, hydrogen storage, and Li-ion battery
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis, a number of clean-energy materials for hydrogen generation, hydrogen storage, and Li-ion battery energy storage applications have been investigated through state-of-the-art density functional theory.

As an alternative fuel, hydrogen has been regarded as one of the promising clean energies with the advantage of abundance (generated through water splitting) and pollution-free emission if used in fuel cell systems. However, some key problems such as finding efficient ways to produce and store hydrogen have been hindering the realization of the hydrogen economy. Here from the scientific perspective, various materials including the nanostructures and the bulk hydrides have been examined in terms of their crystal and electronic structures, energetics, and different properties for hydrogen generation or hydrogen storage applications. In the study of chemisorbed graphene-based nanostructures, the N, O-N and N-N decorated ones are designed to work as promising electron mediators in Z-scheme photocatalytic hydrogen production. Graphene nanofibres (especially the helical type) are found to be good catalysts for hydrogen desorption from NaAlH4. The milestone nanomaterial, C60, is found to be able to significantly improve the hydrogen release from the (LiH+NH3) mixture. In addition, the energetics analysis of hydrazine borane and its derivative solid have revealed the underlying reasons for their excellent hydrogen storage properties. 

As the other technical trend of replacing fossil fuels in electrical vehicles, the Li-ion battery technology for energy storage depends greatly on the development of electrode materials. In this thesis, the pure NiTiH and its various metal-doped hydrides have been studied as Li-ion battery anode materials. The Li-doped NiTiH is found to be the best candidate and the Fe, Mn, or Cr-doped material follows.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. , 83 p.
Keyword [en]
Renewable energy, Materials science, Hydrogen production, Hydrogen storage, Li-ion battery, Density functional theory
National Category
Condensed Matter Physics
Research subject
SRA - Energy; SRA - E-Science (SeRC)
Identifiers
URN: urn:nbn:se:kth:diva-129220ISBN: 978-91-7501-873-7 (print)OAI: oai:DiVA.org:kth-129220DiVA: diva2:650881
Public defence
2013-10-18, Kollegiesallen, Brinellvägen 8, plan04, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20130925

Available from: 2013-09-25 Created: 2013-09-23 Last updated: 2013-09-25Bibliographically approved
List of papers
1. Oxygen- and nitrogen-chemisorbed carbon nanostructures for Z-scheme photocatalysis applications
Open this publication in new window or tab >>Oxygen- and nitrogen-chemisorbed carbon nanostructures for Z-scheme photocatalysis applications
2012 (English)In: Journal of nanoparticle research, ISSN 1388-0764, E-ISSN 1572-896X, Vol. 14, no 8, 895- p.Article in journal (Refereed) Published
Abstract [en]

Here focusing on the very new experimental finding on carbon nanomaterials for solid-state electron mediator applications in Z-scheme photocatalysis, we have investigated different graphene-based nanostructures chemisorbed by various types and amounts of species such as oxygen (O), nitrogen (N) and hydroxyl (OH) and their electronic structures using density functional theory. The work functions of different nanostructures have also been investigated by us to evaluate their potential applications in Z-scheme photocatalysis for water splitting. The N-, O-N-, and N-N-chemisorbed graphene-based nanostructures (32 carbon atoms supercell, corresponding to lattice parameter of about 1 nm) are found promising to be utilized as electron mediators between reduction level and oxidation level of water splitting. The O- or OH-chemisorbed nanostructures have potential to be used as electron conductors between H-2-evolving photocatalysts and the reduction level (H+/H-2). This systematic study is proposed to understand the properties of graphene-based carbon nanostructures in Z-scheme photocatalysis and guide experimentalists to develop better carbon-based nanomaterials for more efficient Z-scheme photocatalysis applications in the future.

Keyword
Carbon nanostructures, Z-scheme photocatalysis, Hydrogen production, Water splitting, Electron mediator, Graphene oxide, Nanoscale clusters
National Category
Nano Technology
Research subject
SRA - Energy; SRA - E-Science (SeRC)
Identifiers
urn:nbn:se:kth:diva-102348 (URN)10.1007/s11051-012-0895-4 (DOI)000307273400005 ()2-s2.0-84863737131 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20120914

Available from: 2012-09-14 Created: 2012-09-14 Last updated: 2017-12-07Bibliographically approved
2. Excellent Catalytic Effects of Graphene Nanofibers on Hydrogen Release of Sodium alanate
Open this publication in new window or tab >>Excellent Catalytic Effects of Graphene Nanofibers on Hydrogen Release of Sodium alanate
Show others...
2012 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 116, no 20, 10861-10866 p.Article in journal (Refereed) Published
Abstract [en]

One of the most technically challenging barriers to the widespread commercialization of hydrogen-fueled devices and vehicles remains hydrogen storage. More environmentally friendly and effective nonmetal catalysts are required to improve hydrogen sorption. In this paper, through a combination of experiment and theory, we evaluate and explore the catalytic effects of layered graphene nanofibers toward hydrogen release of light metal hydrides such as sodium alanate. Graphene nanofibers, especially the helical kind, are found to considerably improve hydrogen release from NaAlH4, which is of significance for the further enhancement of this practical material for environmentally friendly and effective hydrogen storage applications. Using density functional theory, we find that carbon sheet edges, regardless of whether they are of zigzag or armchair type, can weaken Al-H bonds in sodium alanate, which is believed to be due to a combination of NaAlH4 destabilization and dissociation product stabilization. The helical form of graphene nanofibers, with larger surface area and curved configuration, appears to benefit the functionalization of carbon sheet edges. We believe that our combined experimental and theoretical study will stimulate more explorations of other microporous or mesoporous nanomaterials with an abundance of exposed carbon edges in the application of practical complex light metal hydride systems.

Keyword
Total-Energy Calculations, Wave Basis-Set, Storage Materials, Carbon Nanomaterials, Metal-Catalysts, Naalh4, Algorithm, Hydride, Density
National Category
Physical Chemistry
Research subject
SRA - Energy; SRA - E-Science (SeRC)
Identifiers
urn:nbn:se:kth:diva-98004 (URN)10.1021/jp300934h (DOI)000304338500004 ()2-s2.0-84861522843 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20120619

Available from: 2012-06-19 Created: 2012-06-18 Last updated: 2017-12-07Bibliographically approved
3. C-60-mediated hydrogen desorption in Li-N-H systems
Open this publication in new window or tab >>C-60-mediated hydrogen desorption in Li-N-H systems
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2012 (English)In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 23, no 48, 485406- p.Article in journal (Refereed) Published
Abstract [en]

Hydrogen desorption from a LiH + NH3 mixture is very difficult due to the formation of the stable LiNH4 compound. Using cluster models and first-principles theory, we demonstrate that the C-60 molecule can in fact significantly improve the thermodynamics of ammonia-mediated hydrogen desorption from LiH due to the stabilization of the intermediate state, LiNH4. The hydrogen desorption following the path of LiNH4-C-60 -> LiNH3-C-60 + 1/2H(2) is exothermic. Molecular dynamic simulations show that this reaction can take place even at room temperature (300 K). In contrast, the stable LiNH4 compound cannot desorb hydrogen at room temperature in the absence of C-60. The introduction of C-60 also helps to restrain the NH3 gas which is poisonous in proton exchange membrane fuel cell applications.

Keyword
Lithium Amide, Storage, Molecules, Density, Mechanism, H-2
National Category
Nano Technology
Research subject
SRA - Energy; SRA - E-Science (SeRC)
Identifiers
urn:nbn:se:kth:diva-107604 (URN)10.1088/0957-4484/23/48/485406 (DOI)000311138100026 ()2-s2.0-84869064014 (Scopus ID)
Funder
FormasSwedish Research Council
Note

QC 20121214

Available from: 2012-12-14 Created: 2012-12-14 Last updated: 2017-12-06Bibliographically approved
4. Energetic and structural analysis of N2H4BH3 inorganic solid and its modified material for hydrogen storage
Open this publication in new window or tab >>Energetic and structural analysis of N2H4BH3 inorganic solid and its modified material for hydrogen storage
2013 (English)In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 38, no 16, 6718-6725 p.Article in journal (Refereed) Published
Abstract [en]

Here we have exposed the electronic structure, chemical bonding of the light-weight N2H4BH3 inorganic material for hydrogen storage applications and analyzed its hydrogen removal energetics using state-of-the-art first-principles method. The mechanism for the H-host bond weakening in this kind of solid has also been explored. It is shown that the electronic density of states of N(2)H(4)BH(3)d solid near the Fermi level is mainly contributed by the B p-states, H (B) s-states, and the end N p-states. The calculated smallest hydrogen removal energy of N2H4BH3 solid is 4.16 eV. One Li-modified structure has been obtained through ab initio relaxations and its hydrogen removal energies are found dramatically decreased by as much as 50% compared with those of pristine N2H4BH3 solid. The B-H bond weakening is attributed to the elongation of the bond length; for the N H bonds, the weakening is found to be due to the destabilization of N-H bonds before hydrogen removal and the stabilization of residual N-H bond after hydrogen removal. The weakening of these bonds is of great significance for the improvement of hydrogen desorption kinetics of the material. We propose this study should help to deepen understanding of properties of N2H4BH3 inorganic solid and its related materials for hydrogen storage applications and guide experimentalists and engineers to develop better candidate materials for the advance of the field.

Place, publisher, year, edition, pages
Elsevier, 2013
Keyword
Hydrogen storage, Density functional theory, N2H4BH3, Chemical hydride, Hydrogen energy
National Category
Condensed Matter Physics
Research subject
SRA - Energy; SRA - E-Science (SeRC)
Identifiers
urn:nbn:se:kth:diva-129216 (URN)10.1016/j.ijhydene.2013.03.124 (DOI)000319958400018 ()2-s2.0-84877687157 (Scopus ID)
Funder
Swedish Research CouncilFormasThe Wenner-Gren Foundation
Note

QC 20130925

Available from: 2013-09-23 Created: 2013-09-23 Last updated: 2017-12-06Bibliographically approved
5. Pure and Li-doped NiTiH: Potential anode materials for Li-ion rechargeable batteries
Open this publication in new window or tab >>Pure and Li-doped NiTiH: Potential anode materials for Li-ion rechargeable batteries
Show others...
2013 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 103, no 3, 033902- p.Article in journal (Refereed) Published
Abstract [en]

Pure and Li-doped NiTiH hydrides have been explored for their potential applications as anode materials for Li-ion batteries using density functional theory. The diffusion of Li-ion through pure NiTiH lattice has revealed a big enhancement at 600 K with the diffusion coefficient estimated to be 2.3 x 10(-10) m(2) s(-1) or so. The most thermodynamically stable Li-doped NiTiH material has been ascertained, which evidently shows enhanced electrochemical capacity and a minor increase in voltage and unit-cell volume with respect to pure NiTiH.

Keyword
Lithium Batteries, Electron-Gas, Prospects, Hydrides, Metals, Energy
National Category
Physical Sciences
Research subject
SRA - Energy; SRA - E-Science (SeRC)
Identifiers
urn:nbn:se:kth:diva-127504 (URN)10.1063/1.4813596 (DOI)000322146300131 ()2-s2.0-84881533077 (Scopus ID)
Funder
Swedish Research CouncilSwedish Energy AgencyThe Wenner-Gren Foundation
Note

QC 20130902

Available from: 2013-09-02 Created: 2013-08-30 Last updated: 2017-12-06Bibliographically approved
6. Screening study of light-metal and transition-metal-doped NiTiH hydrides as Li-ion battery anode materials
Open this publication in new window or tab >>Screening study of light-metal and transition-metal-doped NiTiH hydrides as Li-ion battery anode materials
Show others...
2014 (English)In: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 258, 88-91 p.Article in journal (Refereed) Published
Abstract [en]

Here we have investigated systematically the effects of various light-metals (Mg, Al) and transition-metals (V, Cr, Mn, Fe, Co, Cu, Zn) on the electrochemical properties of NiTiH hydrides as anodes for Li-ion battery applications. Based on the pristine NiTiH, a screening study in terms of the structure volume, average voltage and specific capacity has been performed to choose the most proper metal dopants. The most thermodynamically stable doping sites (Ni or Ti site) of various dopant metals have been determined respectively. It is finally summarized that in this study, the light metal Al or the transition metals Cr, Mn and Fe have the most comprehensive effects and are the most promising metal dopants for the pristine NiTiH hydride. This theoretical study is proposed to help understand the properties of the material and guide the design and development of more efficient metal-hydrides materials for Li-ion battery anode applications.

Place, publisher, year, edition, pages
Elsevier, 2014
Keyword
Li-ion battery, NiTiH hydride, Doping, Metal, DFT
National Category
Condensed Matter Physics
Research subject
SRA - Energy; SRA - E-Science (SeRC)
Identifiers
urn:nbn:se:kth:diva-129219 (URN)10.1016/j.ssi.2014.02.007 (DOI)000334084900013 ()2-s2.0-84894682282 (Scopus ID)
Funder
Swedish Research CouncilSwedish Energy AgencyThe Wenner-Gren FoundationStandUpCarl Tryggers foundation
Note

QC 20140516.  Updated from submitted to published.

Available from: 2013-09-23 Created: 2013-09-23 Last updated: 2017-12-06Bibliographically approved

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  • nn-NO
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Output format
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