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Studying and Synthesize of H2S Gas Sensors Based on Modified WO3 Nanostructure Thin Films

Kashani, Shima | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40674 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Iraji zad, Aazam; Rahimi, Fereshte
  7. Abstract:
  8. H2S is a toxic gas used in chemical laboratories and industries. H2S is also liberated in nature due to biological processes and also from mines and petroleum fields. At some threshold level, exposure to concentrations over 10 ppm can result in headaches, irritability, dizziness and in some case leads to death. So that introducing sensors which sense H2S at ppm level with the low response time is so essential. The present work emphasizes on H2S resistance-sensing properties of pure and Pd doped WO3 films prepared by Arc discharge method. XRD, SEM, EDAX and XPS were applied to analyze crystal structure, morphology and chemical composition of the films. The analyzes results showed that films have smooth surface with small and evenly distributed grain size. The pure film has grain with sizes at the order of 29.7 nm and the modified film contains grains with sizes around 26.2 nm. Resistance sensing properties of the films were tested in a static system under the same conditions. The sensing properties such as response magnitude, response time, recovery time and stability were measured. Our pure films showed response at the concentration range of 10 to 100 ppm H2S at room temperature. The response magnitude was 23 at room temperature with 25minutes response time. Modifying WO3 films with Pd showed increase in response to 300 with decrease in response time to15 minuets
  9. Keywords:
  10. Gas Sensor ; WO3 ; Hydrogen Sulfide ; Nanostructure

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