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A one-step water based strategy for synthesizing hydrated vanadium pentoxide nanosheets from VO2(B) as free-standing electrodes for lithium battery applications
Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Alexandria University, Egypt.
Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Swedish University of Agricultural Sciences, Sweden.
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Number of Authors: 112016 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, no 46, p. 17988-18001Article in journal (Refereed) Published
Abstract [en]

The synthesis of two dimensional (2D) materials from transition metal oxides, chalcogenides, and carbides mostly involve multiple exfoliation steps in which hazardous solvents and reagents are used. In this study, hydrated vanadium pentoxide (V2O5 center dot nH(2)O) nanosheets with a thickness of a few nanometers were prepared via a facile environmentally friendly water based exfoliation technique. The exfoliation process involved refluxing the precursor, vanadium dioxide (VO2(B)), in water for a few days at 60 degrees C. The proposed exfoliation mechanism is based on the intercalation/insertion of water molecules into the VO2(B) crystals and the subsequent cleavage of the covalent bonds holding the layers of VO2(B) together. The thermal and chemical analyses showed that the approximate chemical composition of the nanosheets is H0.4V2O5 center dot 0.55H(2)O, and the percentage of V-V content to that of V-IV in the nanosheets is about 80(3)% to 20(3)%. The exfoliated aqueous suspension of the V2O5 center dot 0.55H(2)O nanosheets was successfully deposited onto multi-walled carbon nanotube (MW-CNT) paper to form free-standing electrodes with a thickness of the V2O5 center dot 0.55H(2)O layer ranging between 45 and 4 mu m. A series of electrochemical tests were conducted on the electrodes to determine the cyclability and rate capability of lithium insertion into V2O5 center dot 0.55H(2)O nanosheets. The electrodes with the thinnest active material coating (similar to 4 mu m) delivered gravimetric capacities of up to 480 and 280 mA h g(-1) when cycled at current densities of 10 and 200 mA g(-1), respectively.

Place, publisher, year, edition, pages
2016. Vol. 4, no 46, p. 17988-18001
National Category
Inorganic Chemistry
Research subject
Inorganic Chemistry
Identifiers
URN: urn:nbn:se:su:diva-137777DOI: 10.1039/c6ta06571fISI: 000388505400010OAI: oai:DiVA.org:su-137777DiVA, id: diva2:1063886
Available from: 2017-01-11 Created: 2017-01-10 Last updated: 2018-12-04Bibliographically approved
In thesis
1. Aqueous Exfoliation of Transition Metal Oxides for Energy Storage and Photocatalysis Applications: Vanadium Oxide and Molybdenum Oxide Nanosheets
Open this publication in new window or tab >>Aqueous Exfoliation of Transition Metal Oxides for Energy Storage and Photocatalysis Applications: Vanadium Oxide and Molybdenum Oxide Nanosheets
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Two-dimensional (2D) transition metal oxides (TMOs) are a category of materials which have unique physical and chemical properties compared to their bulk counterparts. However, the synthesis of 2D TMOs commonly includes the use of environmental threats such as organic solvents. In this thesis, we developed environmentally friendly strategies to fabricate TMO nanosheets from the commercially available bulk oxides. In particular, hydrated vanadium pentoxide (V2O5∙nH2O) nanosheets and oxygen deficient molybdenum trioxide (MoO3-x) nanosheets were prepared.  The V2O5∙nH2O nanosheets were drop-cast onto multi-walled carbon nanotube (MWCNT) paper and applied as a free-standing electrode (FSE) for a lithium battery. The accessible capacity of the FSE was dependent on the electrode thickness; the thickest electrode delivered the lowest accessible capacity.  Alternatively, a composite material of V2O5∙nH2O nanosheets with 10% MWCNT (VOx-CNT composite) was prepared and two types of electrodes, FSE and conventionally cast electrode (CCE), were employed as cathode materials for lithium batteries. A detailed comparison between these electrodes was presented. In addition, the VOx-CNT composite was applied as a negative electrode for a sodium-ion battery and showed a reversible capacity of about 140 mAh g-1. On the other hand, the MoO3-x nanosheets were employed as binder-free electrodes for supercapacitor application in an acidified Na2SO4 electrolyte. Furthermore, the MoO3-x nanosheets were used as photocatalysts for organic dye degradation. The simple eco-friendly synthesis methods coupled with the potential application of the TMO nanosheets reflect the significance of this thesis in both the synthesis and the energy-related applications of 2D materials.

Place, publisher, year, edition, pages
Stockholm: Department of Materials and Environmental Chemistry (MMK), Stockholm University, 2019. p. 61
Keywords
aqueous exfoliation, vanadium oxide nanosheets, molybdenum oxide nanosheets, energy storage, photocatalysis
National Category
Inorganic Chemistry
Research subject
Inorganic Chemistry
Identifiers
urn:nbn:se:su:diva-162235 (URN)978-91-7797-514-4 (ISBN)978-91-7797-515-1 (ISBN)
Public defence
2019-02-06, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 10:00 (English)
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Available from: 2019-01-14 Created: 2018-12-04 Last updated: 2019-02-07Bibliographically approved

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