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Preparation of Nanocomposites from Carbon Nanostructures and Transtion Metal Oxides and their use in Preparation of Hybrid Electrochemical Capacitors

Rahimi, Sajad | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 49964 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Shahrokhian, Saeed
  7. Abstract:
  8. In the first part, we report a new and simple procedure for preparing reduced graphene oxide /nickel, cobalt hydroxide composite (Ni,Co-OH/rGO/NF via a fast and simple two-step electrochemical method including potentiostatic routes in the presence of Cetyl trimethyl ammonium bromide )CTAB( as a cationic surfactant. In the first step, a piece of nickel foam (NF) is sonicated in a suspension of graphene oxide (GO, 6 mg/L) after dried in an oven, reduced by electrochemically. After that, Ni, Co LDH were co-deposited on the surface of rGO/NF. The resulting modified electrode afforded extremely high specific capacitance of 2133.3 F/g at a current density of 4 A g-1. FE-SEM results showed that nickel/cobalt hydroxide nanosheets deposited on the surface of reduced graphene oxide/nickel foam in the presence of CTAB form denser and thinner nano-scale microstructures compared with other sample prepared in similar way without using the surfactant. This new thin and dense nanosheets morphology facilitates the electron transfer process through the modified electrode. A good cycling stability was obtained for the electrode in alkaline media. EIS measurements showed low values of internal resistance (Rs) and charge transfer resistance (Rct), indicating that the prepared nanocomposite can be promising candidate for supercapacitor applications.In the second part; first we synthesized nano cone array structures on the surface of nickel plate by electroplating method then, nickel/cobalt/ iron sulfide were co-electrodeposited on the surface of nanocone array by using electrochemically method. The resulting modified electrode afforded extremely high specific capacitance of 2031.7 F/g at a current density of 7 A/g in three electrode measurements. FE-SEM results showed that nickel nanocone array have a highly ordered in structure and nickel/cobalt/iron sulfide are in sub-micron size with nanosheets as building subunits. EIS measurements showed low values of internal resistance (Rs) and charge transfer resistance (Rct), indicating that the prepared nanocomposite is a promising candidate for supercapacitor applications
  9. Keywords:
  10. Reduced Graphene Oxide ; Nanosheet ; Surfactants ; Supercapacitor ; Pseudocapacitor ; Nickel Sulfide ; Nickel Nanocones

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