在全球環境日漸惡化與環保意識高漲的影響下，導致光觸媒技術受到學術與產業界的高度重視。二氧化鈦光觸媒會如此受到全球的關切，最主要是因為光觸媒利用源源不絕的太陽光能源與二氧化鈦是一種便宜且被高度研究的材料。
本論文利用熱水解法以起始物為四氯化鈦溶液與氨水合成TiO2粉體。其後段的煆燒程序與特性分析可發現所合成的粉體為不同比例的銳鈦礦相(Anatase)與金紅石相(Rutile)的混合物。其轉化率可由銳鈦礦相與金紅石相的X光粉末繞射峰的比例計算而得。溶液的pH值對二氧化鈦從銳鈦礦相到金紅石相的相轉變溫度與其對應的活化能影響很大。在其後的動力分析發現此反應的動力為三維界面控制。反應機制可由紫外光-可見光光譜儀以及X光粉末繞射儀對待測粉體穿透深度不同來研究。由其結果可知，其反應機制為以core-shell的型態來進行的。
另一方面，本論文亦使用微乳膠水熱法合成奈米二氧化鈦粉體。微乳膠系統之水在油中型(w/o)的水相微胞可作為微反應器來合成奈米級粉體。其後再以150℃ 1h 的水熱處理使粉體結晶化。微乳膠系統中的pH值對最終粉體的型態與粒子大小影響甚巨。pH = 4-6與pH = 7的微乳膠溶液可分別製備出球型以及平版狀的奈米級粒子。能帶的能量可藉由UV-visible的光譜換算出來，且粒子的能帶能量顯示有量子尺寸效應。pH = 7的微乳膠系統所製備出的粉體具有最佳的光觸媒活性與最大的比表面積。

Recently photocatalytic technologies have attracted considerable attention in the scientific researches and industry because the global environmental pollution had become a serious problem.
The thermal hydrolysis method was developed for synthesizing TiO2 powders with starting materials of titanium tetrachloride and NH3 in this study. The subsequent calcination process was performed to obtain the powders with different ratios of anatase and rutile phases. The pH value of the starting solution had significant effects on the phase transformation from anatase to rutile. The temperature and the activation energy of the phase transformation were varied with the different pH value of the starting solution. The conversion was calculated based on the ratio of diffraction intensity of anatase to that of rutile. In the kinetics analysis, the reaction of phase transformation from anatase to rutile was determined to be the three-dimensional phase boundary controlled process. The UV-vis spectroscope and XRD were performed to investigate the mechanism of phase transformation from anatase to rutile. The mechanism of the phase transformation was supposed as the core-shell model.
The hydrothermal microemulsion process was performed to prepare the nano-sized titania particles with anatase phase. Aqueous micelles of water-in-oil with two microemulsions systems were used as microreactors to precipitate the precursor. The precursors were treated hydrothermally at 150℃for 1 h to produce ultrafine titania particles. The morphology and particle size were directly influenced by the pH value of the microemulsion solutions. The particles prepared at pH = 4-6 and 7 of microemulsions showed the spherical and plate-like morphology, respectively. Different mechanisms of the formation of particles also were also supposed in this study. The energy of band gap was estimated from UV-vis spectra, and showed the quantum size effect of the prepared powders. The photocatalytic activity of prepared particles was evaluated using the decomposition of methylene blue solution with titania photocatalyst. The sample prepared from the starting microemulsion at pH = 7 showed a relative maximum photocatalytic activity. The surface area of this sample was also the maximum value between the synthesized samples. The developed process successfully prepared nanosized titania with high photocatalytic activity.

Chapter 1 Literature Review……………………............…………...1
1.1 Introduction to titanium dioxide…………………………...…………1
1.1.1 Introduction to TiO2 in anatase phase…………………..……….1
1.1.2 Introduction to TiO2 in rutile phase……………………..………2
1.2 Process of synthesizing titanium dioxide powders………………...…8
1.2.1 Gas-phase oxidation process…………………………………....8
1.2.2 Thermal hydrolysis process……………………………………..9
1.2.3 Sol-Gel method………………………………………………...10
1.2.4 Microemulsion process………………………………...………11
1.2.5 Hydrothermal process………………………………….………13
1.3 Applications of titanium dioxide………………………………....…23
1.3.1 Photocatalysis……………………………………………….…23
1.3.1.1 Evolution of TiO2 photocatalyst. ……………………............23
1.3.1.2 Principles and Mechanism of photocatalysis………………..24
1.3.1.3 Applications of photocatalysis……………………………....26
1.3.2 Other applications……………………………………………...27
1.4 Synthesizing powders via hydrothermal microemulsion process…..37
1.4.1 The effect of oil phase…………………………………………37
1.4.2 The effect of surfactants……………………………………….38
1.4.3 The effect of aqueous phase and oil-to-water ratio……………38
1.4.4 The effect of salinity…………………………………………...39
1.4.5 The effect of hydrothermal temperature……………………….39
1.4.6 The effect of hydrothermal treatment time…………………….40
1.5 Introduction to nanotechnology……………………………………..45
1.5.1 Evolution of nanotechnology………………………………….45
1.5.2 Top-down and bottom-up techniques of nanotechnology……..46
1.5.3 Selected quantum effect and properties of nanoparticles……...46
1.5.3.1 Surface-to-volume ratio effects………………………...46
1.5.3.2 Quantum confinement effect…………………………...47
1.5.3.3 Tunneling effect………………………………………...49
1.6 Research objectives…………………………………………………53
Chapter 2 Experimental Procedures……………………………..54
2.1 Powder preparation………………………………………………….54
2.1.1 Thermal hydrolysis process……………………………………54
2.1.2 Hydrothermal microemulsion process…………………………55
2.2 Characterization……………………………………………………..57
Chapter 3 Reaction mechanism and kinetics analysis of phase transformation from anatase to rutile using thermal hydrolysis method…………………………………………………………………61
3.1 X-ray powder diffraction study and phase diagram………………...61
3.2 Kinetic analysis of anatase to rutile phase transformation………….62
3.3 Microstructure observation and reaction model.................................68
3.4 Conclusions........................................................................................71
Chapter 4 Characterization of nanosized anatase particles synthesized via hydrothermal microemulsion route…………87
4.1 Formation of anatase-type titania by hydrothermal microemulsion process……………………………………………………………..87
4.2 Effect of the pH of starting microemulsion solution on the morphology of anatase-type titania………………………………...88
4.3 Dependence of pH value in microemulsion solutions on optical property and photocatalytic activity.……………………………….92
4.4 Conclusions………………………………………………………....96
Chapter 5 Conclusions…………..……………………………….113
5.1 Kinetics analysis of phase transformation from anatase to rutile
using thermal hydrolysis route.........................................................113
5.2 Characterization of nanosized anatase particles prepared via hydrothermal microemulsion route.................................................114
References………………………………………………………........114

1. Phase Diagrams for Ceramicists, Fig. 4150-4999, The American Ceramic Society, inc., 76 (1975).
2. W. W. So, S. B. Park, and K. J. Kim, J. Colloid Interf. Sci., 191, 398 (1997).
3. R. J. Gonzalez, R. Zallen, and H. Beger, Physical Review B, 55, 7014 (1997).
4. T. E. Weirich, M. Winterer, S. Seifried, H. Hahn, and H. Fuess, Ultramicrosocpy, 81, 263, (2000).
5. Powder Diffraction File, Card No. 21-1272, Joint committee on powder diffraction standards, Swarthmore, PA.
6. D. Nicholls, Complexes and First-Row Transition Elements, 1st edit. (1974).
7. J. S. Kasper and K. D. Lomsdale, International tables of X-ray crystallography, 2nd edit. (1959).
8. Powder Diffraction File, Card No. 21-1276, Joint committee on powder diffraction standards, Swarthmore, PA.
9. J. Muscat, N. M. Harrison, and G. Thornton, Physical Review B, 59, 2320 (1999).
10. W. A. Weyl and T. Forland, Ind. Eng. Chem., 42, 257 (1950).
11. J. H. Braun, J. Coating Technol., 69, 59 (1997).
12. M.K. Akhtar, Y. Xiong, and S.E. Pratsinis, AIChE J., 37, 1561 (1991).
13. Y. Suyama and A. Kato, J. Am. Ceram. Soc., 68, C154 (1985).
14. A. kobata, K. Kusakabe, and S. morooka, AIChE J., 37, 347 (1991).
15. H. K. Park, D. K. Kim, and C. H. Kim, J. Am. Ceram. Soc., 80, 742 (1997).
16. H. D. Nam, B. H. Lee, S. J. Kim, C. H. Jung, J. H. Lee, and S. Park, Jpn. J. Appl. Phys., 37, 4603 (1998).
17. S. D. Park, Y. H. Cho, W. W. Kim, and S. J. Kim, Journal of Solid State Chemistry, 146, 230 (1999).
18. S. J. Kim, S. D. Park, and Y. H. Jeong, J. Am. Ceram. Soc., 82, 927 (1999).
19. Y. Li, Y. Fan and Y. Chen, J. Mater. Chem., 12, 1387 (2002).
20. H. K. Park, Y. T. Moon, D. K. Kim, and C. H. Kim, J. Am. Ceram. Soc., 79, 2727 (1996).
21. Y. Wei, R. Wu and Y. Zhang, Mater. Lett., 41, 101 (1999).
22. K. P. Kumar, K. Keizer, A. J. Burggraaf, T. Okubo, H. Nagamoto, and S. Morooka, Nature, 358, 48 (1992).
23. M. Gotic, M. Ivanda, A. Sekulic, S. Music, S. Popovic, A. Turkovic, and K. Furic, Mater. Lett., 28, 225 (1996).
24. K. C. Song and S. E. Pratsinis, J. Am. Ceram. Soc., 84, 92 (2001).
25. Z. C. Wang, J. F. Chen, and X. F. Hu, Mater. Lett., 43, 87 (2000).
26. D. C. Hague and M. J. Mayo, J. Am. Ceram. Soc., 77, 1957 (1994).
27. K. P. Kumar, J. Kumar, and K. Keizer, J Am. Ceram. Soc., 77, 1396 (1994).
28. S. Music, M. Gotic, M. Ivanda, S. popovic, A. Turkovic, R. Trojko, A. Sekulic, and K. Furic, Materials Science and Engineering B, 47, 33 (1997).
29. Y. Zhu, L. Zhang, C. Gao, and L. Cao, J. Mater. Sci., 35, 4049 (2000).
30. T. P. Hoar and J. H. Schulman, Nature, 152, 102 (1943).
31. J. H. Schulman, W. Stoeckenius, and L. M. Prince, J. Phys. Chem., 63, 1677 (1959).
32. T. A. Hattn, Surfactant-based separation process, Marcel Dekker, New York (1989).
33. M. P. Pileni, Structure and reactivity in reverse micelles, Plenium, New York (1984).
34. D. J. Shaw, Introduction to colloid and surface chemistry, 4th edit., Butterworths, London (1992).
35. X. Liu, J. Wang, L. M. Gan, S. C. Ng, and J. Ding, Journal of Magnetism and Magnetic Materials, 184, 244 (1998).
36. J. Fang, J. Wang, S. C. Ng, L. M. Gan, C. H. Quek, and C. H. Chew, Materials Letters, 36, 179 (1998).
37. G. W. Morey, J. Am. Ceram. Soc., 65, 343 (1953).
38. Tem-Press Div. Leco Corp. Catalogue.
39. W. J. Dawson, Am. Ceram. Soc. Bull., 67, 1973 (1988).
40. D. W. Johnson Jr and G. L. Messing, Advances in Ceramics, Am. Ceram. Soc., 21, 3 (1987).
41. S. Somiya and T. Akiba, Trans. MRS-Tokyo, 24, 531 (1999).
42. D. Segal, Chemical synthesis of advanced ceramic materials, Cambridge: Cambridge University Press, 182 (1989).
43. M. Yoshimura and S. Somiya, Rep. Lab. Eng. Mat. Tokyo Inst. Of Technology, 9, 53 (1984).
44. S. Yomiya and R. Roy, Bull. Mater. Sci., 23, 453 (2000).
45. A. Fujishima and K. Honda, Nature, 238, 37 (1972).
46. A. Heller, Acc. Chem. Res., 14, 154 (1981).
47. S. N. Frank and A. J. Bard, J. Am. Chem. Soc., 99, 303 (1977).
48. S. N. Frank and A. J. Bard, J. Phys. Chem., 81, 1484 (1977).
49. M. R. Hoffmann, S. T. Martin, W. Y. Choi, and D. W. Bahnemann, Chem. Rev., 95, 69 (1995).
50. A. Fujishima, T. N. Rao, and D. A. Tryk, J. Photochem. and Photobio. C, 1, 1 (2000).
51. A. Hagfeld, and M. Gratzel, Chem. Rev., 95, 49 (1995).
52. A. Fujishima, K. Hashimoto, and T. Watanabe, TiO2 photocatalysis Fundamentals and Applications, 1st edit., BKC Inc. (1999).
53. B. O’Regan and M. Gratze, Nature, 353, 737 (1991).
54. K. D. Schierbaum, U. K. Kirner, J. F. Geiger, and M. Gopel, Sensors and Actuators B, 4, 87 (1991).
55. I. Hayakawa, Y. Iwamotoa, K. Kikutab, and S. Hiranob, Sensors and Actuators B, 62, 55 (2000).
56. E. Cominia, G. Faglia, G. Sberveglieri, Y. X. Li, W. Wlodarski, and M. K. Ghantasala, Sensors and Actuators B, 64, 169 (2000).
57. T. Gessner, K. Gottfried, R. Hoffmann, C. Kaufmann, U. Weiss, E. Charetdinov, P. Hauptmann, R. Lucklum, B. Zimmermann, U. Dietel, G. Springer, and M. Vogel, Microsystem Technologies, 6, 169 (2000).
58. L. S. Ee, J. Wang, S. C. Ng, and L. M. Gan, Mater. Res. Bull., 33, 1045 (1998).
59. W. W. So, S. B. park, K. J. kim, and S. J. Moon, J. colloid interface sci., 191, 398 (1997).
60. H. Cheng, J. Ma, Z. Zhao, and L. Qi, Chem. Mater., 7, 663 (1995).
61. C. J. Barbe, G. Arendse, P. Comte, M. Jirousek, F. Lenzmann, V. Shklover, and M. Gratzel, J. Am. Ceram. Soc., 80, 3157 (1997).
62. Y. Zheng, E. Shi, Z. Chen, W. Li, and X. Hu, J. Mater. Chem., 11, 1547 (2001).
63. K. Yanagisawa, Y. Yamamoto, Q. Feng, and N. Yamasaki, J. Mater. Res., 13, 825 (1998).
64. R. Feynman, Engineering and Science, 23, 22 (1960).
65. N. Taniguchi, Proc. ICPE Tokyo, (1974).
66. E. Drexler, Engines of Creation, Garden City, N.Y. : Anchor Press, 1st edit., (1986).
67. J. Wolfe, The Nanotech Report, (2001).
68. L. E. Brus, J. Chem. Phys., 80, 4403 (1984).
69. G. Binnig, H. Rohrer, C. Gerber and E. Weibel, Appl. Phys. Lett., 40, 178 (1982).
70. H. P. Klug, and L. E. Alexander, X-ray diffraction procedures for polycrystalline and amorphous materials, pp. 491-538 Wiley, New York (1954).
71. R.A. Spurr, and H. Myers, Anal. Chem., 29, 760 (1957).
72. J. H. Sharp, G. W. Brindley, and B. N. Narahari Achar, J. Am. Ceram. Soc., 49, 379 (1966).
73. A. W. Czanderna, C. N. R. Rao, and J. M. Honig, Transactions of the Faraday Society, 54, 1069 (1958).
74. A. A. Gribb and J. F. Banfield, American mineralogist, 82, 717 (1997).
75. C. N. R. Rao, Canadian Journal of Chemistry, 39, 498 (1961).
76. A. Suzuki and R. Tukura, Bulletin of the Chemical Society of Japan, 42, 1853 (1969).
77. K. N. P. Kumar, K. Keizer, and A. J. Burggraaf, J. Mater. Chem., 3, 1141 (1993).
78. K. N. P. Kumar, K. Keizer, and A. J. Burggraaf, J. Mater. Chem., 3, 1151 (1993).
79. J. F. Banfield, B. L. Bischoff, and M. A. Anderson, Chemical Geology, 110, 211 (1993).
80. K. J. D. MacKenzie, Transactions and Journal of the British Ceramic Society, 74, 77 (1975).
81. A. Suzuki and Y. Kotera, Bulletin of the Chemical Society of Japan, 35, 1353 (1962).
82. S. Hishita, I. Mutoh, K. Koumoto, and H. Yanagida, Ceramics international, 9, 41 (1983).
83. Cotton and Wilkinson, Advanced Inorganic Chemistry, 3rd edit., 809-818 (1972).
84. D. Nicholls, Complexes and First-Row Transition Elements, 1st edit., 139-148 (1974).
85. U. Muller, Inorganic Structural Chemistry, New York, pp. 45-46 (1993).
86. H. Cheng, J. Ma, Z. Zhao and L. Qi, Chem. Mater., 7, 663 (1995)
87. I. Kosacki, V. Petrovsky, and H. U. Anderson, Applied Physics Letters, 74, 341 (1999).
88. H. Fujii, M. Ohtaki, and K. Egchi, J. Am. Chem. Soc., 120, 6832 (1998).
89. L. E. Brus, J. Chem. Phys., 80, 4403 (1984).
90. R. Rossetti, R. Hull, J. M. Gibbon, and L. E. Brus, J. Chem. Phys., 85, 2237 (1986).
91. M. L. Steigerwald and L. E. Brus, Acc. Chem. Res.,23, 183, (1990).
92. M. Ogawa and K. kuroda, Chem. Rev., 95, 399 (1995).
93. Y. Wang and N. Herron, J. Phys. Chem., 95, 525 (1991).
94. C. Kormann, D. W. Bahnemann, and W. M. Hoffmann, J. Phys. Chem., 92, 5196 (1988).
95. T. Zhang, T. Oyama, A. Aoshima, H. Hidaka, J. Zhao, and N. Serpone, J. Photochem. Photobiol. A, 140, 163 (2001).