二氧化鈦奈米棒的製備與應用：從光催化反應到染料敏化太陽能電池效率之相關性探討

The Preparation and Application of Titanium Dioxide Nanorods:from Photocatalysis to Dye-Sensitized Solar Cell

楊采穎(Tsai-Ying Yang)

指導教授 ： 蘇昭瑾

國立臺北科技大學/工程學院/有機高分子研究所/碩士(2008年)

https://doi.org/10.6841/NTUT.2008.00564

摘要

本研究分成兩個部分，第一部份主要是探討自製金紅石相的二氧化鈦奈米顆粒成膜在玻璃表面及其與亞甲基藍光裂解效率的相關性。第二部份是以金紅石相的二氧化鈦溶液、粉體及銀/二氧化鈦粉體為主體，做成不同的塗料塗佈在導電玻璃上，測其光電轉換效率，將其應用在染料敏化太陽能電池上。
本實驗以正四丁基氧化鈦為前趨物，與鹽酸混合攪拌後得到白色溶液，利用水熱（hydrothermal）處理於220 oC製備金紅石（rutile）結晶相的二氧化鈦溶液，第一部份以浸漬塗佈及旋轉塗佈法分別將製備好的二氧化鈦溶液鍍於玻璃基材上，再以450 oC煅燒可得到rutile的二氧化鈦薄膜，由實驗結果發現改變浸漬塗佈時重複塗佈與煅燒的次數及旋轉塗佈時塗佈的轉速皆會影響二氧化鈦薄膜的性質及反應性。由電子掃描顯微鏡（SEM）分析薄膜表面型態可得，二氧化鈦顆粒大小約在60~100 nm，薄膜厚度分佈在0.5~7.5 μm。由X光繞射儀（XRD）分析二氧化鈦粉末與薄膜的結晶結構，在紫外光（254 nm）的光源照射下，使亞甲基藍（methylene blue）產生光裂解反應。
第二部份則是先以自製的二氧化鈦奈米棒為載體，以不同濃度的硝酸銀為離子源，利用光催化沈積法製備銀/二氧化鈦奈米棒，並藉由X光繞射儀（XRD）、穿透式電子顯微鏡（TEM）、氮氣吸附儀（BET）、化學分析能譜儀（ESCA）、原子吸收光譜儀（AA）及能量散布儀（EDS）來分析及鑑定其性質。再將自製的二氧化鈦的粉末、水熱完的溶液及銀/二氧化鈦配置成不同的塗料，以刮塗法（doctor-blade） 的方式將塗料分別均勻的塗佈在導電玻璃（FTO）上，以450 oC煅燒製備成二氧化鈦光電極，接著將其浸泡N3染料即可得到吸附染料的工作電極，另外反電極是以濺鍍法得到厚度為20 nm 的Pt電極，注入電解液（I3-/I-）後，組裝成染料敏化太陽能電池元件。最後以模擬太陽光AM 1.5，光強度為100 mW/cm2的光源照射，進行電池的光電轉換效率測試，由結果顯示以水熱完的二氧化鈦溶液（wt%=20%）為材料的電池有最高的光電轉換效率（η）4.1 %，再由表面輪廓儀測其薄膜厚度在12~13 μm時，有較高的效率。

關鍵字

二氧化鈦 ； 金紅石 ； 奈米棒 ； 銀/二氧化鈦 ； 光催化沈積法 ； 亞甲基藍 ； 染料敏化太陽能電池

並列摘要

In the first part of this thesis, we synthesized the rutile TiO2 nanorods under the hydrothermal condition and investigated the correlation between the preparation parameters and the photocatalytic activity of as-prepared TiO2 samples. In the second part of this thesis, we prepared TiO2 nanorods paste which was applied to fabricate the photoanode for DSSC.
The initial sols were prepared by mixing the precursor, titanium (IV) n-butoxide with hydrochloric acid (HCl) and mechanically stirring until a white sol was obtained, followed by hydrothermal treatment at 220 °C. The glass substrate were dip-coated or spin-coated and annealed at 450 °C to result the TiO2 films. The coating conditions, such as spin rate and repeated coating cycle, affect the properties of the TiO2 films. The TiO2 film thickness varied from 0.4 to 7.5 mm. The morphology of the TiO2 films was examined by scanning tunneling microscopy. The grain size of TiO2 particulates is ~ 60 – 100 nm. The X-ray diffraction pattern for the annealed TiO2 powders (no dipping and coating) indicated the formation of rutile phase TiO2. To examine the photocatalytic activity of the as-prepared TiO2 films, the photodegradation of methylene blue was carried out. The possible correlation between the photocatalytic activity and the TiO2 preparation conditions is discussed.
Second, we were prepared Ag/TiO2 nanorods photocataly by photoreduction with various concentration of AgNO3 in order to deposite Ag on TiO2. The results of Ag/TiO2 nanorods were analyzed by XRD, TEM, BET, ESCA, AA and EDS. Then, we prepare four different kinds of paste made by TiO2 nanorods, solution after hydrothermal and Ag/TiO2 nanorods. The composite paste was deposited on conductive glass substrates (FTO) by the doctor-blade technique and calcined at 450 oC. The electrode soaked in absolute ethanol containing N3 dye and the 20nm platinized counter electrodes were fabricated by sputtering. The redox electrolyte (I3-/I-) was introduced into the cell and short-circuit photocurrent (Jsc) and open-circuit voltage (Voc) were measured by using a computerized Keithley 2400 source meter. It was found that the sol-based DSSC exhibited a conversion efficiency of 4.1% under AM 1.5 simulated light irradiation (100 mW/cm2). Finally, the best range of thickness from 12 μm to 13μm as measured with Alpha-step profiler.

並列關鍵字

rutile ； nanorod ； hydrothermal ； photocatalytic deposition ； Ag/TiO2 ； methylene blue ； dye-sensitzed solar cell

參考文獻

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