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Atomistic Modelling of Low Dimensional Materials for Energy Harvesting and Gas Sensing Applications
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.ORCID iD: 0000-0003-4288-8098
2020 (English)Doctoral thesis, comprehensive summary (Other academic)
Description
Abstract [en]

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.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2020. , p. 93
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1938
Keywords [en]
Density functional theory, Low dimensional materials, Energy harvesting, Hydrogen storage, Gas Sensing
National Category
Natural Sciences
Research subject
Physics with spec. in Atomic, Molecular and Condensed Matter Physics
Identifiers
URN: urn:nbn:se:uu:diva-409006ISBN: 978-91-513-0955-2 (print)OAI: oai:DiVA.org:uu-409006DiVA, id: diva2:1424356
Public defence
2020-06-11, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 10:00 (English)
Opponent
Supervisors
Available from: 2020-05-19 Created: 2020-04-17 Last updated: 2020-05-19
List of papers
1. Manipulating energy storage characteristics of ultrathin boron carbide monolayer under varied scandium doping
Open this publication in new window or tab >>Manipulating energy storage characteristics of ultrathin boron carbide monolayer under varied scandium doping
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2017 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, no 14, p. 8598-8605Article in journal (Refereed) Published
Abstract [en]

We report, for the first time we believe, a detailed investigation on hydrogen storage efficiency of scandium (Sc) decorated boron carbide (BC3) sheets using spin-polarized density functional theory (DFT). We analyzed the energetics of Sc adsorption and explored the most favorable adsorption sites of Sc on BC3 sheets with 3.12%, 6.25%, and 12.5% coverage effects. Our investigations revealed that Sc strongly binds on pristine BC3 sheet, with a minimum binding energy of similar to 5 eV, which is robust enough to hinder Sc-Sc metal clustering. Sc, the lightest transition metal, adsorbs a large number of H-2 molecules per atom, resulting in a reasonable storage capacity. With 12.5% Sc-coverage, functionalized BC3 sheets could attain a H2 storage capacity of 5.5 wt% with binding energies suitable for a practical H-2 storage medium.

National Category
Chemical Sciences Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-317700 (URN)10.1039/c6ra24890j (DOI)000393758700061 ()
Funder
Swedish Research CouncilStandUpCarl Tryggers foundation
Available from: 2017-03-17 Created: 2017-03-17 Last updated: 2020-04-17Bibliographically approved
2. Hexagonal Boron Nitride (h-BN) Sheets Decorated with OLi, ONa, and Li2F Molecules for Enhanced Energy Storage
Open this publication in new window or tab >>Hexagonal Boron Nitride (h-BN) Sheets Decorated with OLi, ONa, and Li2F Molecules for Enhanced Energy Storage
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2017 (English)In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 18, no 5, p. 513-518Article in journal (Refereed) Published
Abstract [en]

First-principles electronic structure calculations were carried out on hexagonal boron nitride (h-BN) sheets functionalized with small molecules, such as OLi, ONa, and Li2F, to study their hydrogen (H-2) storage properties. We found that OLi and ONa strongly adsorb on h-BN sheets with reasonably large inter-adsorbent separations, which is desirable for H-2 storage. Ab initio molecular dynamics (MD) simulations further confirmed the structural stability of OLi-BN and ONa-BN systems at 400K. On the other hand, Li2F molecules form clusters over the surface of h-BN at higher temperatures. We performed a Bader charge investigation to explore the nature of binding between the functionalized molecules and h-BN sheets. The density of states (DOS) revealed that functionalized h-BN sheets become metallic with two-sided coverage of each type of molecules. Hydrogenation of OLi-BN and ONa-BN revealed that the functionalized systems adsorb multiple H-2 molecules around the Li and Na atoms, with H-2 adsorption energies ranging from 0.20 to 0.28eV, which is desirable for an efficient H-2 storage material.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2017
Keywords
electronic properties, functionalization, hydrogenation, nanosheets, structural stability
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-320260 (URN)10.1002/cphc.201601063 (DOI)000395423100011 ()28098421 (PubMedID)
Funder
Swedish Research CouncilStandUpSwedish Energy AgencyAustralian Research Council
Available from: 2017-04-18 Created: 2017-04-18 Last updated: 2020-04-17Bibliographically approved
3. Metallized siligraphene nanosheets (SiC7) as high capacity hydrogen storage materials
Open this publication in new window or tab >>Metallized siligraphene nanosheets (SiC7) as high capacity hydrogen storage materials
2018 (English)In: Nano Reseach, ISSN 1998-0124, E-ISSN 1998-0000, Vol. 11, no 7, p. 3802-3813Article in journal (Refereed) Published
Abstract [en]

A planar honeycomb monolayer of siligraphene (SiC7) could be a prospective medium for clean energy storage due to its light weight, and its remarkable mechanical and unique electronic properties. By employing van der Waals-induced first principles calculations based on density functional theory (DFT), we have explored the structural, electronic, and hydrogen (H-2) storage characteristics of SiC7 sheets decorated with various light metals. The binding energies of lithium (Li), sodium (Na), potassium (K), magnesium (Mg), calcium (Ca),scandium (Sc), and titanium (Ti) dopants on a SiC7 monolayer were studied at various doping concentrations, and found to be strong enough to counteract the metal clustering effect. We further verified the stabilities of the metallized SiC7 sheets at room temperature using ab initio molecular dynamics (MD) simulations. Bader charge analysis revealed that upon adsorption, due to the difference in electronegativity, all the metal adatoms donated a fraction of their electronic charges to the SiC7 sheet. Each partially charged metal center on the SiC(7)sheets could bind a maximum of 4 to 5 H-2 molecules. A high H-2 gravimetric density was achieved for several dopants at a doping concentration of 12.50%. The H-2 binding energies were found to fall within the ideal range of 0.2-0.6 eV. Based on these findings, we propose that metal-doped SiC7 sheets can operate as efficient H-2 storage media under ambient conditions.

Keywords
clean energy, functionalization, binding characteristics, dopants
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-364506 (URN)10.1007/s12274-017-1954-z (DOI)000440731800027 ()
Funder
Swedish Research CouncilStandUpSwedish Energy AgencySwedish Institute
Available from: 2018-11-05 Created: 2018-11-05 Last updated: 2020-04-17Bibliographically approved
4. Exploring Doping Characteristics of Various Adatoms on Single-Layer Stanene
Open this publication in new window or tab >>Exploring Doping Characteristics of Various Adatoms on Single-Layer Stanene
2017 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 14, p. 7667-7676Article in journal (Refereed) Published
Abstract [en]

We have performed first-principles calculations based on density functional theory to investigate the doping characteristics of 31 different adatoms on stanene monolayer, which includes the elements of alkali metals (AM), alkaline earth metals (AEM), transition metals (TMs), and groups III-VII. The most stable configurations of all the dopants have been explored by calculating and comparing binding energies of all the possible binding sites. To comment on the uniform distribution of adatoms on stanene, the adsorption energies (E-ads) of adatoms have been compared with their experimental cohesive energies (E-c,) in the bulk phase.A further comparison reveals that the binding energies of most of the studied adatoms on stanene are much stronger than other group IV monolayers. Apart from structural and binding characteristics, bond lengths, adatom adatom distance, charge-transfer mechanism, electronic properties, and work function have also been explored in pristine and doped monolayers. The strong adsorption of adatoms on stanene, tunable electronic properties, and formation of dumbbell structures in the case of AEM and TM shows that doped stanene sheets are worth further exploration.

National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-322817 (URN)10.1021/acs.jpcc.7b00468 (DOI)000399629000011 ()
Funder
Swedish Research CouncilStandUpCarl Tryggers foundation
Available from: 2017-05-30 Created: 2017-05-30 Last updated: 2020-04-17Bibliographically approved
5. Light metal decorated graphdiyne nanosheets for reversible hydrogen storage
Open this publication in new window or tab >>Light metal decorated graphdiyne nanosheets for reversible hydrogen storage
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2018 (English)In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 29, no 35, article id 355401Article in journal (Refereed) Published
Abstract [en]

The sensitive nature of molecular hydrogen (H-2) interaction with the surfaces of pristine and functionalized nanostructures, especially two-dimensional materials, has been a subject of debate for a while now. An accurate approximation of the H-2 adsorption mechanism has vital significance for fields such as H2 storage applications. Owing to the importance of this issue, we have performed a comprehensive density functional theory (DFT) study by means of several different approximations to investigate the structural, electronic, charge transfer and energy storage properties of pristine and functionalized graphdiyne (GDY) nanosheets. The dopants considered here include the light metals Li, Na, K, Ca, Sc and Ti, which have a uniform distribution over GDY even at high doping concentration due to their strong binding and charge transfer mechanism. Upon 11% of metal functionalization, GDY changes into a metallic state from being a small band-gap semiconductor. Such situations turn the dopants to a partial positive state, which is favorable for adsorption of H-2 molecules. The adsorption mechanism of H-2 on GDY has been studied and compared by different methods like generalized gradient approximation, van der Waals density functional and DFT-D3 functionals. It has been established that each functionalized system anchors multiple H-2 molecules with adsorption energies that fall into a suitable range regardless of the functional used for approximations. A significantly high H-2 storage capacity would guarantee that light metal-doped GDY nanosheets could serve as efficient and reversible H-2 storage materials.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2018
Keywords
clean energy, hydrogen storage, binding mechanism, functionalization, storage capacity
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-358258 (URN)10.1088/1361-6528/aac84c (DOI)000435940400001 ()29808826 (PubMedID)
Funder
Swedish Research CouncilCarl Tryggers foundation
Available from: 2018-08-27 Created: 2018-08-27 Last updated: 2020-04-17Bibliographically approved
6. Enriching the hydrogen storage capacity of carbon nanotube doped with polylithiated molecules
Open this publication in new window or tab >>Enriching the hydrogen storage capacity of carbon nanotube doped with polylithiated molecules
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2018 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 444, p. 467-473Article in journal (Refereed) Published
Abstract [en]

In a quest to find optimum materials for efficient storage of clean energy, we have performed first principles calculations to study the structural and energy storage properties of one-dimensional carbon nanotubes (CNTs) functionalized with polylithiated molecules (PLMs). Van der Waals corrected calculations disclosed that various PLMs like CLi, CLi2, CLi3, OLi, OLi2, OLi3, bind strongly to CNTs even at high doping concentrations ensuring a uniform distribution of dopants without forming clusters. Bader charge analysis reveals that each Li in all the PLMs attains a partial positive charge and transform into Li+ cations. This situation allows multiple H-2 molecules adsorbed with each Li+ through the polarization of incident H-2 molecules via electrostatic and van der Waals type of interaction. With a maximum doping concentration, that is 3CLi(2)/3CLi(3) and 3OLi(2)/3OLi(3) a maximum of 36 H-2 molecules could be adsorbed that corresponds to a reasonably high H-2 storage capacity with the adsorption energies in the range of -0.33 to -0.15 eV/H-2. This suits the ambient condition applications. (C) 2018 Elsevier B.V. All rights reserved.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keywords
Carbon nanotubes, Polylithiated molecules, Hydrogen storage, Energetics analysis, Charge transfer, Adsorption energies
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-352558 (URN)10.1016/j.apsusc.2018.02.040 (DOI)000429343200056 ()
Funder
Swedish Research Council
Available from: 2018-08-08 Created: 2018-08-08 Last updated: 2020-04-17Bibliographically approved
7. Exploring two-dimensional M2NS2 (M = Ti, V) MXenes based gas sensors for air pollutants
Open this publication in new window or tab >>Exploring two-dimensional M2NS2 (M = Ti, V) MXenes based gas sensors for air pollutants
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2020 (English)In: Applied Materials Today, Vol. 19, p. 100574-Article in journal (Refereed) Published
Abstract [en]

Albeit a very recent development, Mxenes have offered numerous potential avenues for researchers from physics, chemistry and materials science. Here in, we have explored S-terminated M2N (M = Ti, V) MXenes, which are one of the lightest and thinnest members of the MXene family, for gas sensing applications. We performed spin-polarized DFT calculations with vdW correction to investigate the sensing propensity of several gases such as CH4, CO, CO2, NH3, NO, NO2, H2S, and SO2 on M2NS2 sheets. The adsorption kinetics, charge transfer, electronic density of states (DOS) and electronic transport behaviors are investigated in relation to M2NS2Mxene based nanoscale gas sensor. Among all the gases under consideration, NO, and NO2 exhibit superior sensitivity towards 2D nitride MXenes. Charge transfer analysis reveals that the considerable quantity of charge is transferred from NO, and NO2 gas molecules to Ti2NS2 and V2NS2 MXene sheets, respectively. Spin-polarized DOS reveals that pristine non-magnetic nitride Mxenes transform to magnetic systems upon NO and NO2 adsorption. By computing the electronic transport properties in the form of I–V characteristics for adsorbed gases on M2NS2 and comparing it against the pristine Mxene sheets, distinct changes in I–V relationships can be identified which further substantiate the promising role of Mxenes for gas sensing applications.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Two-dimensional structures, S-terminated nitride MXenes, Ti2NS2, V2NS2, Gas sensor
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-408684 (URN)10.1016/j.apmt.2020.100574 (DOI)
Available from: 2020-04-10 Created: 2020-04-10 Last updated: 2020-04-17
8. Superior sensitivity of metal functionalized boron carbide (BC3) monolayer towards carbonaceous pollutants
Open this publication in new window or tab >>Superior sensitivity of metal functionalized boron carbide (BC3) monolayer towards carbonaceous pollutants
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2020 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 512, article id 145637Article in journal (Refereed) Published
Abstract [en]

The sensitivity of light metal functionalized boron carbide (BC3) sheets towards selected carbonaceous gases like CO, CO2, and CH4 is investigated by using first principles density functional theory calculations. We find that functionalization with alkali (Li, Na, K) and alkaline earth metals (Be, Mg, Ca), is a useful strategy to improve the sensitivity of graphene-like BC3 towards the mentioned gases. A semiconductor-to-metal transformation of BC3 is observed upon the introduction of metal dopants. Gas molecules are adsorbed on the metallized BC3 through weak chemisorption, which is an ideal scenario for gas sensing under practical working conditions. We find that the adsorption energies (Eads) of CO molecule are found to be 1.71, 0.48, 0.34, 0.35, 0.96, and 0.84 eV on Be-, Li-, Na-, K-, Mg-, and Ca-doped BC3, respectively. Similarly, CO2 binds to Li-, Be-, Mg-, and Ca- doped BC3 with Eads of 0.54, 0.87, 0.61, and 0.43 eV, respectively. For CH4, an Eads value of 0.74 eV turns out to be the strongest in case of Be-BC3. Bader charge analysis divulges that the transfer of charges results in the adsorption mechanism of the gases to the metallized BC3. In addition to feasible Eads, change in the work function upon the adsorption of gas molecules further confirms good sensitivity of the metallized BC3 towards CO, CO2and CH4. Based on our findings, we deduce that metal-doped BC3 is an excellent candidate for the efficient sensing of harmful pollutants.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Functionalization, Metal dopants, DOS, Chemisorption, Work function
National Category
Other Chemistry Topics Condensed Matter Physics
Research subject
Physics and Astronomy specializing in Theoretical Physics
Identifiers
urn:nbn:se:uu:diva-408685 (URN)10.1016/j.apsusc.2020.145637 (DOI)000522731700039 ()
Funder
Swedish Research CouncilCarl Tryggers foundation Stiftelsen Olle Engkvist Byggmästare
Available from: 2020-04-10 Created: 2020-04-10 Last updated: 2020-05-28Bibliographically approved
9. Computational insights into the hydrogen storage characteristics of Li and Na decorated 2D Boron Phosphide
Open this publication in new window or tab >>Computational insights into the hydrogen storage characteristics of Li and Na decorated 2D Boron Phosphide
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

Solid-state systems serve as a candidate for clean energy applications driven by technological demands. In this effort, density functional theory (DFT) has become a valuable asset to investigate the intrinsic electronic properties and holds a substantial promise for guiding the discovery of new materials. Herein, we have investigated the Li- and Na-atoms decorated 2D Boron Phosphide (BP) monolayer as a potential candidate for hydrogen storage due to its lightweight and geometric stability. Both the adatoms prefer to adsorb at the center of the hexagon with the binding energies 0.36 and 0.26 eV, respectively. The thermodynamic stabilities of BP, 4Li@BP and 4Na@BP systems were evaluated at room temperature using ab-initio molecular dynamics (AIMD) simulations. It was found that the dispersed Li atoms on the monolayer surface significantly increase both the hydrogen binding energies and the hydrogen storage capacities. With one-sided coverage of Li (Na) atoms, four H₂ molecules were adsorbed with an average binding energy of 0.13 (0.10) eV/H₂. For double-sided adatom coverage, a total of 16H2molecules was captured around 4Li(4Na)/BP complex with an average binding energy of 0.19 (0.17) eV/H₂. The corresponding hydrogen storage capacities were 7.402 (6.446) wt% for Li (Na) doped sheets. These results suggest that boron Phosphide (BP) can act as an effective substrate for H₂ storage by carefully engineering it with metal decoration. 

 

Keywords
Clean Energy, Hydrogen Storage, 2D materials, Boron Phosphide, Li and Na functionalization
National Category
Natural Sciences
Research subject
Physics and Astronomy specializing in Theoretical Physics
Identifiers
urn:nbn:se:uu:diva-408997 (URN)
Available from: 2020-04-16 Created: 2020-04-16 Last updated: 2020-04-17

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