00000ctm a22000004i 4500 UP-99796217613097086 Buklod 20230215105418.0 m |o d | ta 190909s xx d r |||| u| (iLib)UPD-00413166255 DENGII rda eng DMLUC LG 995 2019 M37 B88 Butalid, Rogel Jan B. author. Assessment of the photocatalytic performance and stability of TiO2 coated ZnO nanostructured thin films for methylene blue degradation thesis by Rogel Jan B. Butalid ; Magdaleno R. Vasquez, Jr., thesis adviser. Quezon City College of Engineering, University of the Philippines Diliman 2019. xvi, 90 leaves color illustrations 28 cm text rdacontent unmediated rdamedia volume rdacarrier Thesis (Master of Science in Materials Science and Engineering)--University of the Philippines Diliman June 2019. Available to the general public. The photocatalytic activity of zinc oxide (ZnO) is affected by the rapid charge recombination rates, limited activity in the ultraviolet region, and the decrease in efficiency due to photocorrosion. Hence ZnO is coupled with no more stable metal oxides to overcome these limitations. Coupling ZnO with titanium dioxide (TiO2), which is highly photostable, was seen as a way to reduce charge recombination rates and suppress photocorrosion. In this study, sputtered Zn thin films were thermally oxidized to form nanostructured ZnO thin films. A thin layer of TiO2 was grown on the ZnO thin film by reactive deposition of sputtered Ti in an argon and oxygen atmosphere using a 13.56 MHz radio frequency magnetron sputtering system. The fabricated films were annealed at 500°C for one hour. Homogeneous nanostructured wurtzite ZnO thin films were obtained. The TiO2 layer increased the surface roughness of the nanostructured thin films while shifting the absorption edge to lower wavelengths. The TiO2-coated ZnO thin films reached up to 94% of methylene blue (MB) degradation after 180 min. exposure to a solar light simulator. The TiO2-coated thin films remained stable even after 3 degradation cycles while the bare ZnO film showed a decrease in photodegradation efficiency attributed to loss of material due to ZnO photocorrosion. This was confirmed when higher amounts of Zn²+ ions were detected in bare ZnO films in the MB solution after the degradation tests. Thus, the TiO2 coating effectively decreased the dissolution of ZnO since the concentration of Zn²+ ions was lower when TiO2-coated photocatalyst are used. Aside from improving the photocatalytic efficiency of the metal oxide coupling, the addition of a TiO2 layer on the nanostructured ZnO thin films reduced the effect of photocorrosion on ZnO without significant reduction in the photodegradation efficiency of MB as the test analyt Sewage Purification Photocatalysi. Sewage Purification Color remova. Vasquez, Magdaleno R. Jr. advise. Thes UPD DENG-II LG 995 2019 M37 B88 Thesis