| Summary: | 碩士 === 國立高雄第一科技大學 === 環境與安全衛生工程所 === 98 === This research applied micro arc oxidation (MAO) process to prepare porous top surface photocatalyst thin films from pure titanium plates. Different types and concentrations of electrolytes for MAO operation were tested for finding a better recipe for the TiO2 thin films with better photocatalytic activities. Both formation concentration of hydroxyl radical and density of photocurrent were monitored to represent the oxidative and reductive capabilities of prepared photocatalyst, respectively. This research also applies sputtering technology to depositing highly active TiO2 thin films onto the top surface of some selected porous thin films which had been made from the MAO process. A more active photocatalyst was achieved.
Some important results are observed in the study, which are: more porous structures of the top surfaces of Ti plates can be formed while longer MAO treating time applied, and the pores are getting larger as well. The photocatalytic capability of the prepared photocatalyst was enhanced by increasing MAO-treating time, but too long MAO treating time might spoil their activities. Both chemical crystal structure and physical porosity are two major factors affecting their photocatalytic activities. The films produced in high-pH conditions can achieve higher activities than those produced in acidic conditions due to faster oxidation rate of Ti is achieved and more small-diameter pore is formed in base conditions.
Based on the best preparation recipes of TiO2 thin films in this study, the hydroxyl radical concentration can reach as high as 1.5×10-19 mol/cm2 and photocurrent density can reach as high as 34.3 µA/cm2. The photocatalytic activities of the films can be enhanced while an additional layer of TiO2 can be formed on the top surface of MAO-treated films through the operation of sputtering process.
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