以鉑、碳對二氧化鈦改質之可見光降解氮氧化合物研究及鑑定分析

Visible Light Photocatalytic Degradation of NOx on PtOxor Carbon-modified TiO2 and the Relative Characterization

黃竣鴻(Chun-Hung Huang)

指導教授 ： 王奕凱

國立清華大學/工學院/化學工程學系/博士(2010年)

https://doi.org/10.6843/NTHU.2010.00189

摘要

為了提高光觸媒在太陽光有效的利用，本研究以二氧化鈦(TiO2)為主體進行鉑、碳的改質，將應用拓展至可見光下的氮氧化合物去除(De-NOx)；並利用多項檢測鑑定改質後的樣品性質，最後提出其可能光催化機制。研究分為兩部份，ㄧ部份為鉑的改質，藉由溶膠凝膠法或是含浸法將兩種鉑前驅物Pt(NH3)4(NO3)2、H2Pt(OH)6分別摻雜於TiO2結構內或是擔載於表面後鍛燒200℃；另外也將樣品以氫氣還原並比較不同的Pt氧化價數其反應行為的不同。另ㄧ部分為碳的改質，利用不同碳數與結構的醇類前驅物，以含浸法的方式將碳擔載於市售光觸媒粉體UV100後鍛燒200℃，比較不同醇類改質的光催化活性，以及殘留碳的鍵結形式。
由氮氧化物的光催化降解實驗，配合FE-SEM、TEM、BET、XRPD、Raman、UV-VIS、XPS、TGA、PL光譜等鑑定，在Pt改質方面，PtOx擔載於TiO2表面的可見光催化活性優於TiO2，表面擔載的PtOx為以PtO所佔比例較多的PtO-PtO2混合價數存在；而還原的Pt0擔載於TiO2不具可見光活性，卻可促進NOx反應的完全。在碳改質方面，較高碳數的cyclohexanol擔載於UV100表面可大幅提升其可見光催化活性，並造成C=O鍵結的碳酸鹽類物質殘留，推測其為可見光催化活性的來源。鉑與碳的改質，均能有效增進可見光的催化活性，甚至在紅光下也分別具有33%與54%的總NOx去除率。

關鍵字

二氧化鈦 ； 可見光光觸媒 ； 鉑 ； 碳 ； 溶膠凝膠法 ； 含浸法

並列摘要

To utilize sunlight more efficiently on photocatalysis, in this study, we planed to modify TiO2 by using Pt or carbon species as a visible photo-sensitizer. The modification would expand applications on visible-light photocatalytic degradation of NOx. In addition, various characterizations were employed. Finally, a possible photocatalysis mechanism was proposed. In the aspect of Pt-modified TiO2, Pt(NH3)4(NO3)2 or H2Pt(OH)6 was added in TiO2 matrix or loaded on TiO2 surface by sol-gel process or impregnation method, respectively, followed by calcinations at 200℃. Some modified samples were reduced in H2 flow, and then applied on NOx degradation, for comparison of their reaction behavior related to their Pt oxidation states. In the aspect of carbon-modified TiO2, several different alcoholic precursors were loaded on a commercially available TiO2 (UV100) by impregnation method, followed by calcinations at 200℃, for comparison of the different carbon-numbers and structures of precursors how to influence on visible-light reaction and their bonding forms of carbonic residues.
The results of photocatalytic degradation of NOx were connected with the characterizations of FE-SEM, TEM, BET, XRPD, Raman, UV-VIS, XPS, TGA and PL spectra. In terms of Pt-modified TiO2, the activies of PtOx-loaded TiO2 were higher than those of unmodified TiO2. Moreover, the surfacial PtOx existed on TiO2 surface in forms of PtO-PtO2 mixed valence states and was main in PtO state. In addition, the reduced Pt0-loaded TiO2 showed no visible-light activity, while facilitated the NOx reaction completely. In terms of carbon-modified TiO2, the higher carbon-number precursor loaded on TiO2 surface, the better visible-light activity it presented. The carbonic residues existed in a form of C=O bonding structure, which was speculated as the visible-light responsive source. Both of the Pt- and carbon-modified TiO2 substantially improved the visible-light activities, even under red light illumination with the total NOx removal of 33% and 54%, respectively.

並列關鍵字

Titanium dioxide ； Visible-light-responsive photocatalyst ； Platinum ； Carbon ； Sol-gel method ； Impregnation method

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