光觸媒晶貌調控之研究

Research on Morphological Control of Nanocrystalline Photocatalyst

彭正君(Cheng-Chun Peng)

指導教授 ： 吳乃立

國立臺灣大學/工學院/化學工程學研究所/碩士(2005年)

https://doi.org/10.6342/NTU.2005.00599

摘要

本實驗以溶膠/凝膠水熱法於180oC合成二氧化鈦晶體，並且在水熱過程中於溶膠/凝膠液中加入各式的添加劑共熱，包括一些常見的界面活性劑即有機或無機之酸鹼等，探討其對二氧化鈦晶體晶貌成長的影響。我們發現在酸性環境下，過量的氯離子或是檸檬酸根離子會藉由吸附於晶體表面來抑制晶體的成長，生成等晶向的晶體。一些常見的有機酸(甲酸、乙酸、苯甲酸)或是界面活性劑(PVP, CTAB)都有類似的效果。但在鹼性的環境中，晶體在各個晶向的成長的速率就不盡相同，較易生成短棒狀之晶體。我們發現當溶液中的氨水濃度增加到[NH3/Ti]=50時，二氧化鈦晶體會朝向<001>方向成長，生成含大量{110}晶面之短棒晶體。這些含{110}晶面的二氧化鈦晶體在紫外光(300 nm)的照射之下，在光催化消耗亞甲基藍的反應中較其他晶面展露出更高的反應活性。

關鍵字

二氧化鈦 ； 水熱法 ； 晶貌控制 ； 亞甲基藍

並列摘要

TiO2 crystallites were synthesized by a solution chemistry process consisting of a sol-gel step followed by hydrothermal treatment at 180oC, and the effect of additives, including some commonly used surfactants, organic or inorganic acids and bases, on the morphology of crystallites were investigated. Excess chloride or citrate ions in acidic condition tend to retard the grain growth rate by undue adsorption to the crystallite surfaces, resulting in equidimensionl particles; certain organic acids (formic, acetic and benzoic acid) and surfactants (PVP, CTAB) displayed similar influences on the morphology of synthesized crystallites.

However, the growth rates along different lattice directions tend to differ in some basic conditions, leading to elongated crystallites. With increasing NH3 content from [NH3/Ti] = 0 to 50, TiO2 crystallites were increasingly elongated along <001> to form crystallite having predominantly {110} surface planes. While not significant in methyl orange solution, the surface catalytic activities of the crystallites toward degradation of methyl orange under UV-light (300 nm) illumination was found to increase with increasing {110} plane coverage.

並列關鍵字

TiO2 ； Hydrothermal Method ； Morphology control ； Methylene blue

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