溶膠凝膠法製備氧化鐵與摻鋅氧化鐵薄膜應用於光電化學產氫電極之研究

鄧永門(Yung-men Teng)

指導教授 ： 曾重仁

國立中央大學/工學院/材料科學與工程研究所/碩士(2008年)

摘要

本論文使用溶膠凝膠旋轉塗佈法製備應用於光電化學產氫系統中的半導體氧化鐵薄膜電極，並嘗試摻雜鋅至薄膜之中，以期製作出高光電流與高光電轉換效率的薄膜電極。α相氧化鐵擁有2.3 eV的低能隙，能夠有效的吸收波長小於550 nm的光線，此波長之太陽光約佔太陽光能量中的30 % 。氧化物於電解液中擁有較高的耐腐蝕性，能長久使用符合經濟效益。而溶膠凝膠法能降低目前光電薄膜的高製作成本。本研究嘗試改變熱處理溫度、氣氛與膜厚，並利用光譜儀、XRD、SEM與恆電位儀探討所製備氧化鐵光電薄膜之結構、光學與光電流性質。在實驗中成功製備出表面平整之α相氧化鐵薄膜電極，當厚度為300 nm時，其光吸收率於入射光波長550 nm時達50 %、500 nm時達75 %，在太陽光模擬器的照射下出現0.44 mA/cm2的光暗電流差。摻鋅氧化鐵部份發現鋅摻雜量上升會提高反射率，使光吸收率下降，但鋅摻雜量增至10 at% 時表面產生環狀結構，其產生之光電流較低鋅摻雜電極高。本研究更嘗試改變薄膜厚度，以找出最佳覆膜厚度參數，發現多次覆膜與熱處理的試片雖然使結晶性與光吸收率上升，卻未使光電流上升。

關鍵字

光電化學 ； 氧化鐵薄膜 ； 旋轉塗佈 ； 溶膠凝膠

並列摘要

Semiconducting thin films of iron oxide and iron oxide doped zinc as the electrode for PEC were investigated by a sol-gel spin coating method. The α-Fe2O3 was low band gap material about 2.3 eV and it can absorb light which wavelength is lower than 550 nm and this part of light is about 30% of total solar energy. Oxide was high anticorrosive in electrolyte and has long life for using. Sol-gel method was inexpensive manufacturing which can lower the high price of photoelectric films. In this study, the manufacturing controls temperature and atmosphere in heat treatment and the film thickness and studying in crystal structure, morphology, optic properties and photocurrent density.
The iron oxide thin films synthesized by sol-gel spin coating show flat morphology and α phase structure. Light absorption of the films is 50 % in 550 nm, 75 % in 500 nm when the film thickness is 300 nm. And the films show best photocurrent density about 0.44 mA/cm2. In Zn-doped experiment, the reflection rate of films increases with zinc doping rate and decreases the light absorption. But when zinc doping rate increases to 10 %, the circularity morphology appears and improves the photocurrent density. In the study, we tried to change the film thickness and found that the manufacturing with coating and heat treatment several times will improve the crystallization and light absorption, but the films do not show circularity morphology and induce the low photocurrent density.

並列關鍵字

Photoelectrochemical ； Iron oxide thin film ； Spin coating ； Sol-gel

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