Molecular Ruthenium based Water Oxidation Catalysts and their Immobilization on Electrode Surfaces

by Sheida Rajabi
Doctoral thesis
Date of Examination:2021-12-14
Date of issue:2022-02-11
Advisor:Prof. Dr. Franc Meyer
Referee:Prof. Dr. Inke Siewert
Referee:Prof. Dr. Christian Jooß
Referee:Prof. Dr. Anna Jun.-Krawczuk
Referee:Prof. Dr. Johannes Jun.-Walker
Referee:Dr. Michael John
Persistent Address: http://dx.doi.org/10.53846/goediss-41

 

 

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Abstract

English

Ruthenium complexes are valuable in the field of catalytic water oxidation. Their stability and molecular nature allow for detailed mechanistic insight, and they can be synthetically modified to enhance their activity. Herein, two pyrazolate-bridged (bbp) dinuclear ruthenium water oxidation catalysts equipped with peripheral pyrene groups were synthesized to enable π-π interactions with multi-wall carbon nanotubes (MWCNTs). The reactivity and stability of the resulting hybrids toward oxygen evolution reactions were investigated using several electrochemical and spectroscopic techniques. Moreover, in pursuit of developing stable and active oxide-based hybrid materials, a series of mononuclear ruthenium complexes using dianionic N-donor scaffolds were prepared to study their capability toward water oxidation either electrochemically or chemically in aqueous media. Furthermore, to elucidate the structural and electronic determinants for the water oxidation mechanisms, a new generation of dinuclear ruthenium complexes based on an asymmetric pyrazolate ligand was developed. The synthesis along with the catalytic behavior of these new complexes will be discussed.
Keywords: water oxidation catalysis, ruthenium complexes, immobilization, carbon nanotubes, Oxide surfaces, electrocatalysis, rotating ring disc electrode measurements, transmission electron microscopy, X-ray photoelectron spectroscopy