利用化學水浴法鍍製二氧化鈦光電極薄膜之研究

The study of titanium dioxide photoelectrode thin film by chemical bath deposition

謝宗准(Zong-zhun Xie)

指導教授 ： 洪勵吾

國立中央大學/工學院/能源工程研究所/碩士(2011年)

摘要

摘要
本研究利用化學水浴法在ITO導電玻璃上鍍製出二氧化鈦薄膜，並改變硼酸濃度、水浴溫度、鍍膜層數、熱處理溫度及熱處理氣氛，用以探討薄膜的晶體結構、表面型態、光學性質及光電化學性質。利用光電化學原理於水溶液中吸收太陽能，並將其解離成氫氣應用於發電系統上。
本實驗在改變硼酸濃度下，發現增加硼酸濃度會產生過多的氫氧根離子(OH-)，過多的氫氧根離子會影響二氧化鈦薄膜的生長，導致二氧化鈦薄膜有脫落的現象發生，使得薄膜成形性質變差，且光電流也會降低。鍍膜層數的增加會使薄膜結晶強度增強，當薄膜內外層結構形成之後，鍍膜層數增加至一定程度，會使得薄膜沉積速率開始下降，表面也會越來越粗糙。在真空下燒結，由於缺少氧氣，會使得薄膜於再結晶下形成二氧化鈦時，無法將薄膜完全轉化成二氧化鈦。另外還改變熱處理溫度與水浴溫度對薄膜的影響；實驗結果顯示，在硼酸濃度0.05M、水浴溫度90℃、鍍膜層數2層、熱處理溫度500℃、熱處理氣氛-空氣下，擁有較好的光暗電流值，在無施加偏壓下，其值為126µA/cm2，相當於0.126mA/cm2。

關鍵字

二氧化鈦 ； 光電化學 ； 光電極 ； 化學水浴法

並列摘要

ABSTRACT
In this study, titanium dioxide thin films are deposited on ITO conductive glass substrates with chemical bath deposition (CBD). By changing concentration of boric acid, temperature of bath, number of depositon layers, temperature of annealing and different atmospheres in annealing, the distructure of crystal, surface morphology, and optical and pholoelectrochemical properties of thin films are investigated. The principle of photoelectrochemical is applied in aqueous solution by absorbing solar energy and to convert water into hydrogen, which can then be used in electric generating systems.
It is found that hydroxide ions would be exceeded if concentration of boric acid increases. It would affect the growth of titanium dioxide thin film and result in corrosion and poor forming property of thin films, and the corresponding photocurrent would be thus reduced. The crystaling strength is increased as the number of deposition layers increases. Since the thin film structure is formed, the deposition rate would be decreased as the number of deposition layers achieves in some extent and the surface would be rougher. If the annealing is operated in the vacuum atmosphere, the thin film is unable to form titanium dioxide completely because of the lack of oxygen. Moreover, the influences of annealing and bath temperature are also discussed. The results showed that photocurrent has a better value at the circumstance as following: 0.05M of boric acid concentration, 90℃ of bath temperature, 2 of the number of deposition layers, 500℃ of annealing temperature and air of annealing atmosphere. The photocurrent is 126µA/cm^2, i.e. 0.126 mA/cm^2, without applying bias voltage.

並列關鍵字

Photoelectrochemical ； Titanium Dioxide ； Chemical Bath Deposition ； Photoelectrode

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