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Gold, Palladium and Gold-Palladium Nanoparticles Electrodes Electrodeposited on Indium Tin Oxide and Titanium Oxide for Direct Determination and Reduction of Hexavalent Chromium

Siavash Moakhar, Roozbeh | 2016

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 48649 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Dolati, Abolghasem; Ghorbani, Mohammad
  7. Abstract:
  8. Hexavalent chromium ions (Cr(VI)) is one of the most dangerous heavy ions for the environment, humans and other living organisms. Hence, finding new ways to determine and reduction to the much less toxic trivalent chromium (Cr(III)) is highly important. In this thesis, electrochemical and photoelectrochemical methods have been employed for the direct detection and reduction of Cr (VI). For this purpose, the indium tin oxide (ITO) electrode decorated with gold-palladium bimetallic nanoparticles (AuPd) was used for the determination and reduction of Cr(VI) via electrochemical route. These AuPd decorated electrodes exhibited a wide linear concentration range of 0.001-100 µM, a very low detection limit (S/N=3) of 3 pM, and a high sensitivity of 1.701 µA.µM-1. In other field of study, by combining the advantages of the electrochemical and photocatalytical methods, novel photoelectrochemical sensors based on titanium oxide (TiO2) were introduced to efficiently identify and direct reduce of Cr(VI). Screen-printed TiO2 nanoparticles, porous and well-alligned nanorods decorated with Au plasmonic nanoparticles as well as AuPd bimetallic nanoparticles were investigated. Under sun simulator illumination via the amperometric technique, these AuPd decorated TiO2 nanorods photoelectrodes exhibited the highest sensitivity (17.06 µA.µM-1) ever reported among Au-based electrodes for Cr(VI) detection, with a very low detection limit (S/N=3) of 0.001 µM and wide linear concentration range from 0.005 µM to 100 µM. Fabricated nanostructured electrodes were fully characterized by field emission scanning electron microscope (FESEM), high resolution transmission electron microscope (HRTEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-Vis spectroscopy. Furthermore, sensitivity, stability, repeatability and reproducibility of the electrodes were investigated. Eventually, measurements in real water samples such as laboratory and river water were conducted.


  9. Keywords:
  10. Electrochemical Sensor ; Gold Nanoparticle ; Titanium Oxide ; Hexavalent Chromium ; Photoelectrochemical Sensor ; Gold-Palladium Nanoparticles

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