| Summary: | 碩士 === 國立臺灣師範大學 === 機電科技學系 === 101 === In this study, a method is proposed that using electrophoretic deposition (EPD) to fabricate the titania (TiO2) photocatalyst on stainless steel substrate, and successfully modifying TiO2 photocatalyst by lithium nitrate (LiNO3) to be visible light-responsive to effectively degrade contaminants. Firstly, the two-step synthesis method was used to produce TiO2/water nanofluid with alginates as a dispersant to enhance suspension performance and reduced bubble problem from electrolysis of water. The characteristics measurement of TiO2/water nanofluid and methylene blue (MB) photocatalytic degradation experiments were carried out. Then, we used the constant current electrophoretic deposition method with a stainless steel substrate for the electrode, the TiO2 deposited on positive electrode to form the TiO2 coated specimens. We check the uniformity and cracks of coating surface on the completed specimens to determine the optimal parameters of EPD process by a optical microscope (OM) and scanning electron microscope (SEM). Finally, the selected specimen was put into the test box of gaseous pollutants to conduct the photocatalytic degradation of formaldehyde experiments for nine hours under radiation of the LED light board with wavelength of 380-385 nm, 427-432 nm, and 460-465 nm separately.
The results showed that the properties of TiO2/water nanofluid were changed after doping LiNO3. MB experiments could be observed the TiO2/water nanofluid with LiNO3 of 0.02M had best result of photocatalytic degradation, and the degradation rate could reach to 34%. In the EPD process, the optimum process parameters of unmodified, modified by soaking LiNO3, and modified by codeposition of LiNO3 were 7mA/9min, 7mA/9min, and 5mA/10min, respectively. The degradation of formaldehyde experiment using specimen with best process parameters was found the wavelength of irradiation did affect the photocatalytic properties of the specimen. The LiNO3 doped specimen had best degradation of formaldehyde at 427-432 nm of irradiation wavelength, and two kinds of ways to dope LiNO3 had a significant effect. The results showed that after LiNO3 doped could achieve photocatalytic degradation under visible light and the optimum photocatalytic performance should be according to the wavelength of irradiation between 427-432 nm.
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