Suyun ayrışma reaksiyonu için inorganik / polimerik yapılı katalizörler

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 field has been centered on the development of efficient water oxidation and reduction catalysts. The first 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 x 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 quantified 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 Diffraction (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 confirm 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 efficient 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 efficient 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.