| The preparation of TiO2 film is one of the most important questions in the field of photocatalysis research. Traditional techniques of preparation of TiO2 film such as dip coating from suspension, sol gel related methods and vapor deposition have a variety of limitations. So the development of convenient, effective and low-cost preparation method has important significance for the extensive application of photocatalysis technology. In this work, TiO2 positive sol particles prepared by a sol-gel technique were immobilized on aluminum alloy plates by electrophoretic deposition (EPD). EPD can give thick and uniform film within a short time compared with other techniques. The effect of electro- phoretic condition for the photocatalytic activity of TiO2 film was evaluated using ethylene as reactant, and the photocatalytic activity of TiO2 film prepared by EPD and dip coating was compared. The physical and chemical properties including the crystal and morphological structure of the film,the size and band-gap-edge of TiO2 particles were characterized by XRD, SEM, AFM, DRS. TiO2 film with high photocatalytic efficiency was obtained by adding an additive to the precursor TiO2 sol. The reason why the addition of the additive to TiO2 sol can improve the photocatalytic activity was discussed by determining the size and mobility of TiO2 particles and the viscosity and zeta potential of sol. The results showed (1) TiO2 film with high photocatalytic activity was immobilized on aluminum alloy plates by EPD on condition that the temperature of TiO2 sol was 25℃,the potential applied for electrophoresis was 2V and lasted for 3min , and the resulting film was calcinated at 500℃ for 1h. (2) the conversion of ethylene over TiO2 film prepared by EPD (called EP-film) was 3 times higher than that over TiO2 film prepared by dip coating (called DC-film). But a more compact film with higher loading and larger size of TiO2 but lower specific photocatalytic efficiency (ethylene conversion over unit mass TiO2 and unit area of TiO2 film) was obtained by EPD compared with dip coating method. (3) the addition of non-ion surfactant polyethylene glycol (PEG) to TiO2 sol could effectively improve the specific photocatalytic activity over the EP-film. The conversion of ethylene of EP-film changed with the change of the concentration of PEG. Optimum specific photocatalytic activity was found in the film prepared by EPD from TiO2 sol containing 50g/L PEG, which was 9 times more than that of the film prepared from sol without PEG. To investigate the effect of the addition of PEG on the property of TiO2 sol, the properties of sol were measured. It was found that the addition of PEG reduced the zeta potential of TiO2 sol, the mobility and size of TiO2 particles, which leaded to the change of mechanism of EPD and lowered the EP-film packing density. And the specific area of the film was enhanced for the decomposition of PEG at high temperature.The innovations of this work include: (1) investigating the conditions of EPD of TiO2 film systemically, and comparing the morphological structure and properties of EP-film with those of DC-film. (2) preparing TiO2 film with high photocatalytic activity by EPD from the TiO2 sol containing PEG for the first time. (3) discussing the effect of PEG in the process of preparation by measuring the electrokinetic properties of TiO2 sol. Here we provide a new method for the preparation of effective TiO2 film with high photocatalytic activity and develop a new approach for the application research of TiO2 technology.
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