TUNGSTEN OXIDE MODIFIED ELECTRODES AND THEIR ELECTROCATALYTIC APPLICATIONS
Project no. 516 · Status: Kapanmış · 2018
Summary
Nanostructured transition metals and their oxides are considered as attractive functional materials due to their outstanding catalytic properties. In this thesis, it was aimed to search the electrocatalytic effect of tungsten oxide deposited on several electrodes and to study its composites with other metal nanoparticles. For this purpose, glassy carbon electrode was for electrochemical deposition of WOx species along with platinum nanoparticles in pursue of synergic effect and following the characterization studies, catalytic performances of the novel electrodes have been tested for oxygen reduction reaction (ORR). The synergic effect was attributed to the hyper d- hypo-d interaction of the composite. Multivalent character of the tungsten species in the composite has also contributed to the significant catalytic activity. Analytical application of the method covers the non-enzymatic sensor development for hydrogen peroxide as an alternative way for daily used disinfectant analysis. In the second part of the thesis, pencil graphite electrodes modified with WOx was used as a support material for aptasensor fabrication for the detection of Ochratoxin A (OTA) based on the Electrochemical Impedance Spectroscopic (EIS) measurements in the presence of 5 mM ferricyanide ions. Covalent binding efficiency of NH2-Apt by EDC/NHS mechanism was confirmed by comparing the results obtained with NH2-Apt bound to the electrode surface through adsorption. The differences in Rct levels clearly indicated the efficiency of the EDC/NHS mechanism probably via -OH groups on the metal oxide film. Then, the solution parameters (tungstate ion concentration, pH and aptamer concentration) along with operating conditions have been optimized for OTA detection. Selectivity was ensured by using another mycotoxin, Zearalenone (ZEA) and the calibration graphs have been constructed in nanomolar levels. In the final part of the thesis, tungsten oxide film has been electrodeposited on the titanium nanotubes (TNT) and then, by setting the potential at an appropriate value, the composite film was applied for the Photoelectrocatalytic (PEC) degradation of several azo dyes. The application conditions of this binary-oxide film to Rhodamine B degradation have been optimized and kinetic studies were also carried out to clarify the degradation mechanism. In conclusion, synergic interaction between the TNT and WO3 offers a superior catalytic activity and display a potential for the use in solar irradiation inherited from the chemical properties of the modifier. Overall studies can be evaluated as different aspects of electrocatalytic activities of tungsten oxide have been clarified in this thesis to contribute the studies of this kind in the literature.