Fabricating Of Titania Nanotube Arrays And The Effect Of Photoelectrocatalysis On Its Morphology And Composition

Titanium dioxide has been intensively investigated as a semiconductor photocatalytic material for solar energy conversion and environmental purification since Fujishima and Honda discovered the photocatalytic splitting of water on TiO2 electrodes in 1972. In 1999, Zwilling and co-workers achieved self-organized porous TiO2 by anodizing a Ti-based alloy in an acidic, fluoride-based electrolyte. Extensive research has shown that TiO2 have excellent characteristics in photoelectrocatalytic degradation of organic pollutants. Its special nano-architectures offer a large internal surface area and the precisely oriented structure makes them excellent electron pathway for charge transfer between interfaces.There are three main ways to fabricate titania nanotube arrays(TNAs):template method, wet chemical method and anode oxidation method. Anode oxidation method has been chosen in my research because it's easy to control. The research is dedicated to investigate the morphology and surface composition various before and after photoelectrocatalysis. The main results of the study are:1) We successfully formatted of highly-oriented titaniaTNAs by anodization method in aqueous and non-aqueous electrolyte containing fluoride ions, respectively, and studied the effect of preparation conditions on the structure, morphology, and chemical composition.2) We attempted to investigate the modification of TNA's morphology before and after photocatalysis. We found the top part of the TNAs were etched by the PEC process to a certain degree. Some falcate and annular scraps detached from TNAs' surface. The main reason for low catalytic activity is caused by amount C impurity in Ti substrate. Besides, catalyst composition may change after photocatalysis. XPS was used to inspect the change of the components and chemical states of TNAs. The BE of O1s have two main peaks:one at around 529.5eV for the regular lattice oxygen and the other at 531.7eV which is ascribed to the oxygen in the hydroxyl. Compare the XPS profile in the region of C1s binding energy, there was a sharp decrease in the quantity of carbon. The BE peaks centered at 286eV may be associated to ethanol remained on the surface of TNAs after sonication. Also the oxygen to titanium ratio had decreased after photoelectric catalysis. Both the morphology change and composition vary influence the photocatalytic activity may cause the ultimately failure of the catalyst.