| 1. |
- De Sarkar, Abir, et al.
(författare)
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Electronic charge transport through ZnO nanoribbons
- 2014
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Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier BV. - 0022-3697 .- 1879-2553. ; 75:11, s. 1223-1228
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Tidskriftsartikel (refereegranskat)abstract
- I-V characteristics of ZnO nanoribbons (NRs) have been investigated using density functional theory coupled to non-equilibrium Green's Function. The current through the NRs drops with the increasing NR width, leveling off to 1.66 and 0.42 mu A in zig-zag and arm-chair NRs respectively for widths similar to 20 angstrom at 3 V of electrical bias. The transconductance as well as the current flowing through the arm-chair NRs decays exponentially with NR width for both odd and even number of dimer lines traversed. The current through the zig-zag NRs falls off exponentially with NR width, being insensitive to the odd or even numbers of zig-zag lines appearing along the normal to the charge transport direction.
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| 2. |
- Hussain, Tanveer, et al.
(författare)
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Enhancement of energy storage capacity of Mg functionalized silicene and silicane under external strain
- 2014
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 105:12, s. 123903-
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure, stability, and hydrogen storage capacity of strain induced Mg functionalized silicene (SiMg) and silicane (SiHMg) monolayers have been studied by means of van der Waals induced first principles calculations. A drastic increase in the binding energy of Mg adatoms on both the monolayers under the biaxial symmetric strain of 10% ensures the uniform distribution of dopants over the substrates. A significant positive charge on each Mg accumulates a maximum of six H-2 molecules with H-2 storage capacity of 8.10% and 7.95% in case of SiMg and SiHMg, respectively. The average adsorption energy for H-2 molecules has been found ideal for practical H-2 storage materials.
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| 3. |
- Hussain, Tanveer, et al.
(författare)
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Functionalization of hydrogenated graphene by polylithiated species for efficient hydrogen storage
- 2014
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Ingår i: International journal of hydrogen energy. - Uppsala : Elsevier BV. - 0360-3199 .- 1879-3487. ; 39:6, s. 2560-2566
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Tidskriftsartikel (refereegranskat)abstract
- The hydrogen (H-2) storage capacity of defected graphane (CH) functionalized by polylithiated species CLi3 and CLi4 has been investigated by means of first-principles DFT calculations. The stability and electronic structures of these potential H-2 storage materials have also been studied. The binding of these lithium rich species (CLi3, CLi4) to the CH sheet has been found to be strong enough to avoid clustering. The nature of bonding in C-Li and C-C has been revealed by Bader charge analysis. It has been found that when both sides of CH sheet are functionalized by polylithiated species, a storage capacity of more than 13 wt % can be achieved with adsorption energies of H-2 in the range of 0.25 eV-0.35 eV, which is suitable for an efficient H-2 storage.
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| 4. |
- Hussain, Tanveer, 1981-, et al.
(författare)
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Hexagonal Boron Nitride Sheet Decorated by Polylithiated Species for Efficient and Reversible Hydrogen Storage
- 2013
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Ingår i: Science of Advanced Materials. - Uppsala : American Scientific Publishers. - 1947-2935 .- 1947-2943. ; 5:12, s. 1960-1966
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Tidskriftsartikel (refereegranskat)abstract
- In the quest for promising hydrogen storage materials, we have performed first principles calculations on CLi3 and OLi2 decorated hexagonal boron nitride (h -BN), sheet. The strong binding of the polylithiated species to pristine and doped BN sheet and the large distance between these functionalized species ensure their uniform distribution over the sheet without being clustered. MD simulations have also confirmed the stabilities of both functionalized systems. Bader analysis and density of states reveals the bonding nature in the systems. A reasonably high H2 storage capacity with the adsorption energies within the desired window suggests that these systems hold promise as efficient H2 storage mediums.
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| 5. |
- Hussain, Tanveer, 1981-, et al.
(författare)
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Polylithiated (OLi2) functionalized graphane as a potential hydrogen storage material
- 2012
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Ingår i: Applied Physics Letters. - USA : AIP Publishing. - 0003-6951 .- 1077-3118. ; 101:24, s. 243902-
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogen storage capacity, stability, bonding mechanism, and the electronic structure of polylithiated molecules (OLi2) functionalized graphane (CH) has been studied by means of first principle DFT. Molecular dynamics have confirmed the stability, while Bader charge analysis describes the bonding mechanism of OLi2 with CH. The binding energy of OLi2 on CH sheet has been found to be large enough to ensure its uniform distribution without any clustering. It has been found that each OLi2 unit can adsorb up to six H-2 molecules resulting into a storage capacity of 12.90 wt. % with adsorption energies within the range of practical H-2 storage application.
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| 6. |
- Hussain, Tanveer, et al.
(författare)
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Strain and doping effects on the energetics of hydrogen desorption from the MgH2 (001) surface
- 2013
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Ingår i: Europhysics letters. - : IOP Publishing. - 0295-5075 .- 1286-4854. ; 101:2, s. 27006-
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Tidskriftsartikel (refereegranskat)abstract
- On the basis of first-principles calculations we have systematically investigated the energetics of hydrogen desorption from the MgH2 (001) surface. Based on total energy and electronic structure calculations, two modes namely strain and doping of selected dopants (Al, Si, Ti) and the combined effect of both on the dehydrogenation energies (ΔH) of MgH2 (001) systems have been analyzed. The maximum improvement in ΔH has been obtained with the combined effect of doping and strain. Among all the dopants, Al gives the lowest value of ΔH when the system Al-MgH2 is subjected to a 7.5% biaxial symmetric strain whereas the Si-MgH2 systems show the least improvement in ΔH. The doping of Ti on MgH 2 (001) is also very beneficial even without strain. The reduction in ΔH is caused by the charge localization on the metal atoms, destabilization and the weakening of metal-hydrogen bonds.
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| 7. |
- Hussain, Tanveer, et al.
(författare)
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Strain induced lithium functionalized graphane as a high capacity hydrogen storage material
- 2012
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 101:10, s. 103907-
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Tidskriftsartikel (refereegranskat)abstract
- Strain effects on the stability, electronic structure, and hydrogen storage capacity of lithium-doped graphane have been investigated by state-of-the-art first principles density functional theory. Molecular dynamics simulations have confirmed the stability of Li on graphane sheet when it is subject to 10% of tensile strain. Under biaxial asymmetric strain, the binding energy of Li of graphane (CH) sheet increases by 52% with respect to its bulk's cohesive energy. With 25% doping concentration of Li on CH sheet, the gravimetric density of hydrogen storage is found to reach up to 12.12 wt.%. The adsorption energies of H 2 are found to be within the range of practical H 2 storage applications.
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| 8. |
- Kaewmaraya, Thanayut, et al.
(författare)
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Strain-induced tunability of optical and photocatalytic properties of ZnO mono-layer nanosheet
- 2014
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Ingår i: Computational materials science. - : Elsevier BV. - 0927-0256 .- 1879-0801. ; 91, s. 38-42
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Tidskriftsartikel (refereegranskat)abstract
- Strain-induced tunability of several properties of ZnO monolayer nanosheet has been systematically studied using density functional theory. The band gap of the sheet varies almost linearly with uniaxial strain, while it shows a parabola-like behavior under homogeneous biaxial strain. Tensile strain reduces ionicity of Zn-O bonds, while compressive strain increases it. This provides ample implications for the photocatalytic dissociation of water molecules and the scission of polar molecules on ZnO nanosheet. The dynamical stability of the sheet assessed by the calculation of its vibrational frequencies has shown the sheet to be unstable for 10% and 7.5% compressive biaxial homogeneous strain.
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| 9. |
- Li, Yunguo, et al.
(författare)
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Strain-induced stabilization of Al functionalization in graphene oxide nanosheet for enhanced NH3 storage
- 2013
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Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 102:24, s. 243905-
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Tidskriftsartikel (refereegranskat)abstract
- Strain effects on the stabilization of Al ad-atom on graphene oxide (GO) nanosheet as well as its implications for NH3 storage have been investigated using first-principles calculations. Tensile strain is found to be very effective in stabilizing the Al ad-atom on GO. It strengthens the C-O bonds through an enhanced charge transfer from C to O atoms. Interestingly, Al's stability is governed by the bond strength of C-O rather than that of Al-O. Optimally strained Al-functionalized GO binds up to 6 NH3 molecules, while it binds no NH3 molecule in unstrained condition.
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| 10. |
- Liu, Peng, et al.
(författare)
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Shear strain induced indirect to direct transition in band gap in AlN monolayer nanosheet
- 2014
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Ingår i: Computational materials science. - : Elsevier BV. - 0927-0256 .- 1879-0801. ; 86, s. 206-210
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Tidskriftsartikel (refereegranskat)abstract
- The electronic band structure of aluminum nitride (AlN) nanosheets under different kinds of strains has been investigated. Our first principles based studies show that the homogeneous biaxial strain is most effective as compared to uniaxial and shear strain in tuning the band gap. Large shear strain (>= 7.5%) and 10% uniaxial strain along the zig-zag direction induces an indirect-to-direct transition in band gap. The response of these 2 dimensional AlN nanosheets to strain is different from that of its 3 dimensional bulk phase counterparts to pressure. Quantum confinement effects govern the behavior of the former. The dynamical stability of AlN nanosheets have also been assessed under different modes of strains through phonon dispersion calculations. The AlN nanosheets are found to be dynamically stable under tensile strain and shear strain along zig-zag directions, while the sheets are found to be unstable under compressive strain.
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| 11. |
- Naqvi, S. Rabab
(författare)
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Atomistic Modelling of Low Dimensional Materials for Energy Harvesting and Gas Sensing Applications
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Energy crisis and pollution are the two biggest issues of the present times which are extremely important to address on priority. Scientists/Researchers are trying to explore and create alternate means of energy production which are sustainable and free from greenhouse emissions. Use of the hydrogen (H2) as an energy carrier can promise energy sustainability, economic viability, and environmental friendliness. H2 is abundant in nature and delivers the highest energy density compared to all types of fossil fuels. However, the gaseous nature of the H2 makes its storage difficult for practical applications. Previously employed H2 storage strategies (liquefaction and pressurized storage) suffer from economic and safety concerns. H2 storage in solid-state materials via non-dissociative adsorption is the most suitable technique. However, adsorption energies of the H2 with the storage medium are typically very weak therefore operations under ambient working conditions are not possible. We used density functional theory to design the H2 storage media, which are capable to adsorb H2 in a non-dissociative manner with high gravimetric capacity and adequate adsorption energies for storage under the ambient conditions. Our findings point to the fact that the H2 adsorption on the functionalized nanostructures is the most efficient approach for the materials based storage. Furthermore, for environmental safety and monitoring perspective, we investigated and proposed novel two-dimensional nanomaterials that are capable to sense and capture hazardous gases from the environment. In short, this thesis work is an attempt towards designing efficient materials for H2 based energy harvesting and gas sensing applications.
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| 12. |
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| 13. |
- Qian, Zhao, et al.
(författare)
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Pure and Li-doped NiTiH : Potential anode materials for Li-ion rechargeable batteries
- 2013
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 103:3, s. 033902-
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 14. |
- Qian, Zhao, et al.
(författare)
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Screening study of light-metal and transition-metal-doped NiTiH hydrides as Li-ion battery anode materials
- 2014
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Ingår i: Solid State Ionics. - : Elsevier. - 0167-2738 .- 1872-7689. ; 258, s. 88-91
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 15. |
- Sun, Weiwei, et al.
(författare)
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Improvement in the desorption of H-2 from the MgH2 (110) surface by means of doping and mechanical strain
- 2014
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Ingår i: Computational materials science. - : Elsevier BV. - 0927-0256 .- 1879-0801. ; 86, s. 165-169
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Tidskriftsartikel (refereegranskat)abstract
- In this letter, density functional theory has been employed to investigate the release or desorption of hydrogen from the MgH2 (1 1 0) surface. To improve upon the energetics for hydrogen desorption from this system, the effects of strain and doping by Al, Si, Ti have been explored. Both of these two effects have been found to be effective. The strain applied along the X direction induces more prominent effects than along the Y direction. Regarding the doping, the system doped with Al gives the most noticeable effect. The Si doped system shows the least improvement while the Ti doped system lies in between as compared to the other two. The combination of doping and strain effects is found to be more efficacious.
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| 16. |
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| 17. |
- Sun, Weiwei, et al.
(författare)
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The effects of strain and doping on the release of hydrogen fromthe MgH2(110) surface
- 2013
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In this letter, density functional theory has been employed to investigate the release ordesorption of hydrogen from the MgH2(110) surface. To improve upon the energetics for hydrogendesorption from this system, the effects of strain and doping by Al, Si, Ti have been explored.Both of these two effects have been found to be effective. The strain applied along the X directioninduces more prominent effects than along the Y direction. Regarding the doping, the systemdoped with Al gives the most noticeable effect. The Si doped system shows the least improvementwhile the Ti doped system lies in between as compared to the other two. The combination ofdoping and strain effects is found to be more efficacious.
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