二氧化鈦-二氧化錫電極對酸性七號染料光電降解反應之研究

本研究以溶膠凝膠法製備二氧化鈦及二氧化鈦/二氧化錫奈米光電極，進行光電性質及光電催化酸性橙色七號(acid orange 7﹐AO7)染料分解。製得的銳鈦礦主要為(112)結晶面，金紅石為(110)結晶面。同時含有銳鈦礦及金紅石結晶材料的光電效率大於只單獨含銳鈦礦或金紅石者。500℃煅燒之材料粒徑約為30nm，但會有團聚現象。二氧化錫具有穩定二氧化鈦粒徑的效果，尤其在高的煅燒溫度，且二氧化錫會降低金紅石結晶出現的溫度。二氧化錫可提高二氧化鈦的光電效率，尤其是可見光的光電轉換系統，同時以TiO2/SnO2=9:1至7:3樣品經600℃ 煅燒之效率為佳。氧化物鍍層厚度有一最適值存在。AO7溶液在酸性時反應效率大於鹼性溶液。反應物遵循Langmuir-Hinshelwood吸附模式，但反應速率並不能簡化為擬一階反應模式。反應速率對濃度趨近零階關係。純二氧化鈦有可觀察的可見光效應，但並不明顯，加入10%的二氧化錫後，光電催化反應效率迅速提升。TiO2/SnO2(7:3)電極含浸乙醇煅燒後，可見光電催化活性明顯提升。AO7的可見光光電催化分解的有部分是經由電洞引起的氧化反應進行，部分則可能經由光感應模式所引發。

關鍵字

二氧化鈦；光電極；溶膠凝膠；酸性橙色7號染料；二氧化錫

並列摘要

The photoelectrochemical (PEC) bleaching of a textile azo dye, acid orange 7 (AO7), on TiO2 or TiO2/SnO2 thin film electrodes prepared by a modified sol-gel method irradiated by xenon or visible light were carried out. The (112) and (110) were the preferred orientations for the anatase and rutile phases of TiO2, respectively. A synergetic effect between rutile and anatase phases on the PEC efficiency was revealed. The particle sizes of TiO2 and TiO2/SnO2 were estimated to be ca. 30nm by FESEM after calcination at 500℃, but the aggregation between particles was also accompanied. Incorporation of SnO2 can prevent TiO2 from aggregation, diminish the particle size and reduce the temperature, at which anatase phase changed into rutile phase. The TiO2/SnO2 electrodes, calcinated at 600℃, with TiO2/SnO2 of 9:1 to 7:3 explored higher performance than other compositions. An optimum thickness of the oxide film was needed to achieve maximum PEC efficiency. The bleaching rate of AO7 in the acidic solution is superior to that in the basic solution by PEC method. The Langmuir-Hinshelwood model can be adopted to describe the adsorption of AO7 on the electrode; however, it can not be simplified to a pseudo first order reaction due to larger AO7 concentration and/or lower surface area of the electrode. TiO2/SnO2 with Ti/Sn of 9:1 exhibited high bleaching rate of AO7 under visible light. Impregnating TiO2/SnO2(7:3) electrode with ethanol followed by calcination significantly enhanced the photodegradation rate of AO7 under visible light inadiation. The decolorization of AO7 may be partly originated from the hydroxyl radical attacking, and partly resulted from the photosensitization by AO7 itself and/or carbon residues followed by the electrons transferring to the electrode.

並列關鍵字

acid orange 7 ； titanium dioxide ； tin oxide ； photoelectrode ； sol-gel

參考文獻

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二氧化鈦-二氧化錫電極對酸性七號染料光電降解反應之研究

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