Investigation of the photocatalytic properties of semi conductive metal oxides

Advanced oxidation processes (AOPs), in a broad sense, are a set of chemical treatment procedures designed to remove organic (and sometimes inorganic) materials in water and wastewater by oxidation through reactions with hydroxyl radicals (·OH). This method aims to transform harmful substances in wastewater into harmless products (water, carbon dioxide and mineral salts) by "decomposing" in the environment where they are present, with a semiconductor activated using Ultra Violet or visible light. In particular, dye molecules and aromatic materials can absorb visible light. Studies have shown that Zinc Oxide is more effective as a photo catalyst in wastewater treatment. In this thesis, it is aimed to convert carsenijonits into harmless compounds with higher rate and reproducibility by improving their photocatalytic properties by applying Boron element doping of Zinc Oxide semiconductor photo catalysts. The films has fabricated using by Chemical bath deposition method. The films fabricated with additive ratios of 0.5%, 1.5% and 2% were tested under Ultra violet and visible light in the treatment of wastewater containing Methylene Blue, Reactive Red 180 organic dyes, which are important pollutants and show toxic properties. According to the results, while the removal efficiency was 100% for the 2% boron added sample under UV-A irradiation, this efficiency was 63% under visible light. In addition, the reusability tests of these films were made and it was determined that the films did not deteriorate and yield loss even after 15 repetitions for the 2% boron added sample. According to the structural characterization results, it was determined that the structure was deposited on the substrates the wurzite crystal phase. As a result of the morphological analysis, it was observed that the hexagonal nano-scaled rods covered the film surface. While the optical band gap energies were calculated for undoped and %2 boron doped samples as 3.15eV and 3.05 eV, respectively. The activation energy values of the films determined by the temperature dependent current-voltage measurement method using by homemade experimental setup. Accordingly, the activation energies of the films in the low temperature region were between 22meV and 44meV, while the activation energy calculated that it was between 59meV and 99meV in the high temperature region.