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University of Western Ontario

1. Qin, Hanna. Synthesis of VO2 Nanomaterials Using Green Solvents for Thermochromic Window Coatings.

Degree: 2017, University of Western Ontario

Progress in the development of energy-efficient coatings has led to recent investigations of smart windows with the ability to control heat and light. Of particular interest for this dissertation is the fabrication of vanadium dioxide (VO2) thermochromic nanomaterials using an environmentally friendly approach with good performance for optical switching. Tungsten (W) doped VO2/GO (graphene oxide) hybrids were successfully prepared using a one-step hydrothermal method. At 2 at. % doping, VO2 nanotubes were successfully synthesized with tunable phase transition temperatures (Tc) achieved as low as 42 °C. In addition, various experimental parameters including reaction temperature, reaction time, and W doping concentration were examined. Compared to the other reaction parameters, reaction time was found to have the most important influence on the vanadium morphology, phase purity and phase Tc. In addition to nanotube structure, nanofiber shaped VO2 was synthesized via an environmental friendly sol-gel method with supercritical CO2. ScCO2 was found to help facilitate nanostructure formation and maintain high surface areas of the VO2 nanostructure. The vanadium products were characterized by XRD, XPS, SEM, EDX and DSC. At a reaction temperature of 40 °C, microsphere structure was formed with a Tc around 80 °C. Further increasing reaction temperature to 70 °C led to nanobelt structure forming, which gave a Tc around 80 °C. Reaction temperature was found to play a signification role in phase purity, morphology. The reaction pressure and volumetric ratio R showed only a minor effect on nanostructure. The mechanism of formation of VO2(M) microspheres and nanofiber structure was further investigated by in-situ Fourier transmission infrared (ATF-FTIR) analysis. The results showed that pentavalent vanadium was much easier to synthesize than tetravalent vanadium with a lower reaction temperature. Nanofiber formation was enhanced by a higher volumetric ratio and higher reaction temperature. Significant band shifts in the 1350-1520 cm-1 region of the FTIR spectrum indicated a structural change from sphere to fiber formation. The FTIR results also indicated that the formation of nanofibers was favored by one-dimensional condensation, while microspheres were favored by three-dimensional condensation. .

Subjects/Keywords: vanadium dioxide; nanostructure; smart window coating; FTIR; scCO2; Other Chemical Engineering

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Qin, H. (2017). Synthesis of VO2 Nanomaterials Using Green Solvents for Thermochromic Window Coatings. (Thesis). University of Western Ontario. Retrieved from https://ir.lib.uwo.ca/etd/5113

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Qin, Hanna. “Synthesis of VO2 Nanomaterials Using Green Solvents for Thermochromic Window Coatings.” 2017. Thesis, University of Western Ontario. Accessed July 23, 2018. https://ir.lib.uwo.ca/etd/5113.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Qin, Hanna. “Synthesis of VO2 Nanomaterials Using Green Solvents for Thermochromic Window Coatings.” 2017. Web. 23 Jul 2018.

Vancouver:

Qin H. Synthesis of VO2 Nanomaterials Using Green Solvents for Thermochromic Window Coatings. [Internet] [Thesis]. University of Western Ontario; 2017. [cited 2018 Jul 23]. Available from: https://ir.lib.uwo.ca/etd/5113.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Qin H. Synthesis of VO2 Nanomaterials Using Green Solvents for Thermochromic Window Coatings. [Thesis]. University of Western Ontario; 2017. Available from: https://ir.lib.uwo.ca/etd/5113

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

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