Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/97965
標題: 二氧化鈦粉體之光降解染料反應與光激發電荷載子之關聯性研究
Correlation between Dye Photodegradation and Carrier Dynamics on TiO2 Powders
作者: 洪培瑄
Pei-Hsuan Hung
關鍵字: 時差性吸收光譜;二氧化鈦;缺陷;入陷電荷;染料光降解;time-resolved absorption spectroscopy;titanium oxide;defects;charge trapping;dye photodegradation
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Hu, 'Effects of particle size of TiO2 on photocatalytic degradation of methylene blue in aqueous suspensions,' Industrial & Engineering Chemistry Research, 38 (2), 373-379 (1999). [31] A. Houas, H. Lachheb, M. Ksibi, E. Elaloui, C. Guillard, J. M. Herrmann, 'Photocatalytic degradation pathway of methylene blue in water,' Applied Catalysis B: Environmental, 31, 145-157 (2001). [32] C. Galindo, P Jacques, A. Kalt, 'Photodegradation of the aminoazobenzene acid orange 52 by three advanced oxidation processes: UV/H2O2, UV/TiO2 and VIS/TiO2: Comparative mechanistic and kinetic investigations,' Journal of Photochemistry and Photobiology A: Chemistry, 130 (1), 35-47 (2000). [33] I. K. Konstantinou, T. A. Albanis, 'TiO2-assisted photocatalytic degradation of azo dyes in aqueous solution: kinetic and mechanistic investigations: A review,' Applied Catalysis B: Environmental, 49, 1-14 (2004). [34] D. A. Panayotov, S. P. Burrows, J. R. Morris, 'Photooxidation mechanism of methanol on rutile TiO2 nanoparticles,' The Journal of Physical Chemistry C, 116, 6623-6635 (2012). [35] A. Litke, Y. Su, I. Tranca, T. Weber, E. J. M. Hensen, J. P. Hofmann, 'Role of adsorbed water on charge carrier dynamics in photoexcited TiO2,' The Journal of Physical Chemistry C, 121, 7514-7524 (2017). [36] P. H. Hung, 'Carrier dynamics on TiO2 powders studied by time-resolved absorption spectroscopy,' Toyota Technological Institute Master's Thesis (2018). [37] N. Murakami, O. O. P. Mahaney, R. Abe, T. Torimoto, B. Ohtani, 'Double-beam photoacoustic spectroscopic studies on transient absorption of titanium(IV) oxide photocatalyst powders,' Journal of Physical Chemistry C, 111(32), 11927-11935 (2007). [38] A. D. Paola, M. Bellardita, L. Palmisano, 'Brookite, the least known TiO2 photocatalyst,' Catalysts, 3(1), 36-73 (2013).
摘要: 
本實驗以時差性紅外線吸收光譜,探討銳鈦礦及金紅石相的二氧化鈦粉體在持續光源照射下之光激發電荷載子的行為,並研究其載子與有機染料光降解間之相關性。由載子的累積過程可發現,對銳鈦礦相的二氧化鈦而言,絕大部分的電子是以自由電子存在;對金紅石相的二氧化鈦而言,經過光激發的電子會快速的進入中間能隙,接著再緩慢的激發至傳導帶,這個現象顯示電子在二氧化鈦中的行為與其相態相關;此外,累積的電子數量也與二氧化鈦的粒徑相關,當銳鈦礦相二氧化鈦的粒徑由9奈米增加至400奈米時,自由電子與入陷電子數量可增加10倍至20倍;而金紅石相二氧化鈦的入陷電子則是在受光激發後20秒內迅速增加後減少。
此外,在長時間紫外光照射下,當銳鈦礦相的粒徑由9奈米增加至400奈米時,其對於亞甲基藍及甲基橙的光降解能力可增加10倍;而當金紅石相的二氧化鈦粉體的粒徑由20奈米增加至250奈米時,其亞甲基藍及甲基橙的光降解能力可增加2倍。此現象與其累積的自由電子數量呈現正相關,且對降解染料而言,反應活性點的數量也是一個影響降解能力的因素。換言之,在光致染料降解反應中,比表面積並非唯一主要影響降解效率的原因,自由電子的數量在光催化反應中也是相當重要。

Behavior of photogenerated charge carriers in anatase and rutile TiO2 powders was investigated under continuous light irradiations by time-resolved infrared (IR) absorption spectroscopy. The accumulation process of carriers revealed that most of the carriers survived as free electrons for the anatase TiO2; on the contrary, electrons were soon trapped to the midgap and then slowly being excited to the conduction band for the excited rutile TiO2. This finding strongly suggests a phase-dependent behavior of electrons for the TiO2. In addition, the number of accumulated electrons is dependent on particle size of the TiO2. For anatase TiO2 powders, the amount of both free and trapped electrons raises 10 to 20 times as the particle sizes increases from 9 nm to 400 nm. In the case of rutile, after the excitation, the number of trapped electrons rapidly increases within 20 s and decreases afterwards.
Under the UV light irradiations, degradation of methylene blue and methyl orange dyes for anatase TiO2 powders raises 10 times as the particle sizes increases from 9 nm to 400 nm. In addition, the degradation of methylene blue and methyl orange dyes for rutile TiO2 powders raises 2 times as the particle sizes increases from 20 nm to 250 nm. The results are in a good agreement with the number of free electrons being examined by the IR absorption spectroscopy. The number of reactive sites on the particle surface is also a factor to the dye degradation. In other words, specific surface area is not always the main factor to the photodegradation. The number of active electrons is equally important to photocatalysis reactions.
URI: http://hdl.handle.net/11455/97965
Rights: 同意授權瀏覽/列印電子全文服務,2021-08-27起公開。
Appears in Collections:材料科學與工程學系

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