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Synthesis and Characterization of 2D-WS2 Nanostructures for Gas Sensing Applications

Ahmadvand, Hassan | 2021

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 54772 (48)
  4. University: Sharif University of Technology
  5. Department: Institute for Nanoscience and Nanotechnology
  6. Advisor(s): Iraji Zad, Azam; Mohammadpour, Raheleh
  7. Abstract:
  8. Nowadays, beside of two-dimensional tungsten disulfide nanosheets, its hybrid nanostructures also provide active sites for physisorption of gas molecules due to their high surface-to-volume ratio, surface active site (such as sulfur vacancies, surface defects, and p-n junctions) and active edges, and are very attractive for gas sensing applications. In this research, tungsten disulfide layered crystallines were grown by chemical vapor phase transport and its two-dimensional nanoflakes were prepared by liquid exfoliation method. So, a thin film of the nanoflakes was deposited on a silicon oxide substrate by drop casting method, and its gas sensing properties were investigated for water and ethanol vapor at room temperature. To improve the gas sensing performance of WS2 nanoflakes, its hybrid nanostructures were prepared based on graphene oxide nanoribbons. The characterization results based on scanning electron microscopy, energy dispersive X-Ray spectroscopy, Raman spectroscopy and X-Ray diffraction, confirmed the heterojunctions between the WS2 hexagonal nanosheets and graphene oxide nanoribbons. The results showed that the response of the hybrid samples exposed to 1 ppm of ethanol increased more than 55 and 125 times higher compared to pristine graphene oxide and pristine WS2 nanosheets samples respectively, and also 42 times higher than that of 100 ppm of N2, H2, CO, and Ar gases. The flexibility of hybrid nanostructures was studied on Kapton tape substrate with a bending radius of 1 cm, and after 30 bending times of the substrate, its gas response decreased less than 10% compared to the initial state. In the following, a triboelectric nanogenerator was used as a power supply to obviate the limitations of battery usage, and the performance of hybrid samples was investigated exposed to different values of relative humidity (R.H). The results confirmed that the WS2/GONRs hybrid nanostructure can be used to prepare a self-powered humidity sensor at room temperature utilizing a triboelectric nanogenerator
  9. Keywords:
  10. Triboelectric Nanogenerator ; Graphene Nanoribbons ; Chemical Vapor Transport and Condensation (CVTC) ; Self-Powered Sensor ; Ethanol Gas Sensor ; Drop-Casting Method ; Two Dimentional Hybrid Nanostructures ; Two-Dimensional Tungsten Disulfide Nanosheets

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