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Electrochemical Deposition of Co-Mn LDH/Ni-Co-S as an Electrocatalyst for Electrochemical Water Splitting Reactions

Askarzadeh Torghabeh, Mostafa | 2024

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 56857 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Ghorbani, Mohammad; Barati Darband, Ghasem
  7. Abstract:
  8. The development of alternative energy sources is a prominent area of scientific research. Hydrogen, with its exceptional energy density, has emerged as a particularly promising candidate among these new energy sources. An effective technique for generating hydrogen is through the electrochemical process of water splitting. To enhance this process, it is crucial to investigate the development of electrocatalysts with high electrocatalytic activity. Among the potential options, sulfides of transition metals show promise. An essential difficulty in electrochemical water splitting is the development of a bifunctional catalyst that is both active and stable for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). By utilizing electrochemical deposition of nano-sulfide compounds of transition metals, it is possible to build a structure that enhances surface activity, as well as improves both electron transport and mass transfer. This configuration results in accelerated liberation of hydrogen bubbles from the surface. This study presents a straightforward, efficient, logical, and cost-effective approach to creating a highly efficient catalyst for the process of water splitting. Two layers of coating were applied to the surface of nickel foam in the current investigation. The Ni-Co-S coating was applied using the electrochemical deposition method with deposition currents of 10, 20, and 50 mA.cm-2. The Co-Mn LDH coating using cyclic voltammetry method at coating scanning rate (5, 10, 20, 30 and 50 (mV/S)) in fixed coating cycle number (10 cycles) and also in variable cycle number (5, 10, 20, 30 and 50) was performed at a constant coverage scan rate (50 mV/s). The work effectively achieved the creation of nanosheets on the nickel foam substrate. Field emission scanning electron microscopy (FESEM) was employed, together with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD), to analyze the surface properties of the coating. The results indicate that the most effective sample exhibits a significant electrocatalytic activity in the hydrogen evolution reaction, with an overpotential of 24 mV at a current density of 10 mA.cm-2 (η=100) and a Tafel slope of 55 mV/dec. Similarly, it also demonstrates a high electrocatalytic activity in the oxygen evolution reaction, with an overpotential of 310 mV at a current density of 10 mA.cm-2 and a Tafel slope of 48 mV/dec. After 10 hours of electrolysis at a cathodic current density of 100 mA.cm-2, the overpotential of the Co-Mn LDH @ Ni-Co-S electrode only changed by 4 mV. This demonstrates the exceptional electrochemical durability of this coating in both working conditions and an alkaline environment
  9. Keywords:
  10. Electrocatalysts ; Electrochemical Deposition ; Hydrogen Evolution Reaction ; Oxygen Evoloution Reaction (OER) ; Electrochemical Water Splitting ; Hydrogen Producing ; Electrocatalytic Activity

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