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Investigation of Water Splitting Performance of Zeolitic Imidazolate Framework-67 and Graphene Quantum Dots Composite

Kabirian Moghaddam, Mohammad Reza | 2021

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 54614 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Simchi, Abdolreza
  7. Abstract:
  8. Depleting resources and heavy pollution of fossil fuels have drawn the world's attention to clean energy and the most ideal one is hydrogen. Water splitting is one of the most effective ways to produce hydrogen and due to slow kinetic rate different kind of catalysts (optical, electrochemical, etc.) are developed for this reaction. In this work a ZIF-67 and N-doped graphene quantum dots composite is developed and its electrocatalytic performance in oxygen evolution reaction is evaluated. The synthesized graphene quantum dots are between 2-4 nm and the incorporation of nitrogen atom in their structure was verified by FTIR analysis. The metal-organic framework which is produced in this work has narrow and normal size distribution with average diameter of 374 nm and is very porous with specific area of 1764.4 m2.g-1. Adding graphene quantum dots to ZIF-67 (518.7 ohm) decrease charge transfer resistance by 82.37% (91.43 ohm for best composite) which means this electrode accelerate the reaction kinetic better. Also, electrochemical surface shows graphene quantum dots can act separately as electrocatalytic active sites. Finally, after assessing electrocatalytic performance of different structures by using linear sweep voltammetry it was found that the composite with performance can achieve current density of 10 and 100 mA.cm-1 at overpotential of 343 and 520 mV respectively. This performance is far better than ZIF-67 (10 mA.cm-1 at overpotential of 504). The Tafel slope of this composite is 86 mV.dec-1 and it shows reasonable stability after 6h. in conclusion the developed composite shows good performance as oxygen evolution reaction electrocatalyst in water splitting
  9. Keywords:
  10. Electrocatalysts ; Graphene Quantum Dots (GQDs) ; Metal-Organic Framework ; Water Splitting ; Oxygen Evoloution Reaction (OER) ; Electrochemical Water Splitting

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