Inorganic / polymeric assemblies as catalysts for water splitting
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Splitting water with sunlight is an attractive and promising research topic over the last two decades since it produces a non-carbon-based resource, hydrogen, which is a suitable energy carrier due to its high energy output and for being environmentally friendly. A great deal of research in this eld has been centered on the development of e cient water oxidation and reduction catalysts. The rst part of the thesis focuses on a novel photosensitizer-water oxidation catalyst (PS-WOC) dyad. A Ru metal coordinated pyridine-based ligand and a cobalt-iron pentacyanoferrate have been used as the photosensitizer and water oxidation catalyst, respectively. In this assembly, poly(4-vinylpyridine) serves as the bridging group between two units mainly to enhance the performance and stability of the system compared to its analogous intermolecular system. A 5-fold improvement on the catalytic activity has been achieved with a turnover frequency (TOF) of 5:6 10-4 s-1 under 1 hour light illumination and a turnover number (TON) of 11 in a 6-hour catalytic study. Evolved oxygen was quanti ed with gas chromatography. Structural characterization was carried out by Fourier Transform Infrared Spectroscopy (FTIR), Ultraviolet-Visible Spectroscopy (UV-Vis), X-Ray Photoelectron Spectroscopy (XPS), X-Ray Powder Di raction (XRD), Scanning Electron Microscopy (SEM), and Energy-dispersive X-Ray Spectroscopy (EDX) techniques. Comparative XPS and FTIR studies were performed on pristine and post-catalytic samples to con rm the stability of the dyad. In the second part of the study, a facile synthetic pathway using poly(4- vinylpyridine) as a polypyridyl platform has been reported for the formation of a cobalt-based metallopolymer. Electrochemical studies indicate that the metallopolymer acts as an e cient H2 evolution catalyst similar to cobalt-polypyridyl complexes. Furthermore, metallopolymer can be transformed to cobalt particles when a cathodic potential is applied in the presence of an acid. It has been found that these cobalt particles also serve as e cient hydrogen evolution catalysts. Approximately 80 µmoles of H2 gas can be collected during 2 h of electrolysis at -1.5 V (vs. Fc+/0) in the presence of 60 mM of acetic acid. A comprehensive study of the electrochemical and electrocatalytic behavior of cobalt-poly(4-vinylpyridine) was discussed in detail.
KeywordsWater Reduction Catalyst
Hydrogen Evolution Catalyst
Light-Driven Water Oxidation Catalyst
Light-Driven Oxygen Evolution Catalyst
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Mishra, R.; Ülker, E.; Karadas, F. (Wiley-VCH Verlag, 2017)Although cobalt-based heterogeneous catalysts are the central focus in water oxidation research, interest in copper-based water oxidation catalysts has been growing thanks the great abundance of copper and its biological ...
Carbon supported nano-sized Pt-Pd and Pt-Co electrocatalysts for proton exchange membrane fuel cells Kadirgan, F.; Kannan, A. M.; Atilan, T.; Beyhan, S.; Ozenler, S. S.; Süzer, Şefik; Yörür, A. (2009)Nano-sized Pt-Pd/C and Pt-Co/C electrocatalysts have been synthesized and characterized by an alcohol-reduction process using ethylene glycol as the solvent and Vulcan XC-72R as the supporting material. While the Pt-Pd/C ...
Gold supported on ceria doped by Me3+ (Me = Al and Sm) for water gas shift reaction: Influence of dopant and preparation method Andreeva, D.; Kantcheva, M.; Ivanov, I.; Ilieva, L.; Sobczak, J. W.; Lisowski, W. (2010)Gold catalysts supported on ceria doped by Sm and Al were studied. The influence of the preparation method, as well as the nature of dopants on the structure, properties and WGS activity are investigated. The applied methods ...