Preparation and characterization of metal oxide supported group 9B metal nanoparticles and their use as electrocatalysts in water splitting

2022-9-2
Akbayrak, Merve
Hydrogen has been regarded as a crucial energy carrier due to its high energy density. Therefore, there is an increasing attention for the production of hydrogen. Among the hydrogen production methods, water splitting is one of the well-known environmentally friendly methods for the production of hydrogen. Although a large variety of catalysts have been tested in water splitting, the development of efficient and long-lived electrocatalysts is still an important issue. This thesis covers the preparation, characterization and the catalytic use of metal oxide supported group 9B metal nanoparticles (Co, Rh, Ir) in water splitting. Metal nanoparticles were formed on the surface of various metal oxides such as titania, zirconia and ceria by a simple impregnation method and the catalysts were characterized by advanced analytical techniques. The electrocatalytic activity and stability of the catalysts on glassy carbon electrode for both oxygen and hydrogen evolution reactions in water splitting were investigated. The onset potential and overpotential of Ir/CeO2 were found as -13.0 and -23.0 mV, respectively. Moreover, among the other Rh and Co based catalysts, Ir/CeO2 provided lower Tafel slope (38.7 mV.dec-1), higher turnover frequency (1.95 s-1) and higher exchange current density (2.69 mA.cm-2). Ir/CeO2 shows superior stability even after 20 000 cycle in acidic environment which makes Ir/CeO2 as a promising electrocatalyst for HER. On the other hand, Co/CeO2 exhibited impressive performance for the oxygen evolution reaction in an alkaline environment with low overpotential (0.368 V), low Tafel slope (63.0 mV.dec-1), and high TOF value. Although the commercial Co3O4 loses its activity to a great extent after the stability test, for the Co/CeO2 no noticeable change was observed in Tafel slopes and overvoltages.

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Citation Formats
M. Akbayrak, “Preparation and characterization of metal oxide supported group 9B metal nanoparticles and their use as electrocatalysts in water splitting,” Ph.D. - Doctoral Program, Middle East Technical University, 2022.