可見光應答氮氧化鈦光觸媒之材料特性與光催化活性探討

Materials Characteristics and Photodegradation of Visible Responded TiO2-xNx Photocatalysts

王士庭(Shin-Ting Wang)

指導教授 ： 郭俞麟

大同大學/工程學院/材料工程學系所/碩士(2009年)

摘要

二氧化鈦經由氮之摻雜，可以縮短光學能隙、使吸收光範圍從紫外光區段延伸至可見光區段，亦能提升光觸媒在可見光之光催化活性。本研究以濕式含浸法(Wetness Impregnation)摻雜尿素至商業化二氧化鈦(Degussa P25)中，製備不同氮濃度摻雜二氧化鈦光觸媒粉末。接以利用XRD、ESCA以及UV-visible DRS等不同鑑定方法，分析所製備之氮氧化鈦光觸媒之結晶組成、成份鍵結與光學特性。再於不同光照環境下，針對亞甲基藍溶液進行光催化活性評估。藉由光觸媒之特性分析結果，選擇一組最佳參數，探討其長期穩定性。
分析結果顯示，利用濕式含浸法所製備之不同氮濃度摻雜二氧化鈦光觸媒，與商業化二氧化鈦作比較，確實可以提升可見光之吸收效率，使其吸收效率由紫外光範圍朝可見光範圍偏移；而在可見光範圍進行亞甲基藍之光催化活性試驗，結果顯示，不同氮濃度摻雜之氮氧化鈦光觸媒之反應效率常數(k)與光催化效率，皆高於二氧化鈦。其中以尿素濃度為2M，在350 ℃鍛燒2小時所製備之氮氧化鈦光觸媒表現最佳，經過6小時的可見光照射，其反應效率常數(k)為0.0043 min-1，光催化效率可達67.11 %；經過6小時的BLED照射，其反應效率k值達0.0067 min-1，降解效率高達71.53 %。
長期穩定性測試部分，將濃度為2M之氮氧化鈦光觸媒分別置於可見光照射以及紫外光照射之環境，每隔一段時間取樣進行UV-visible DRS及可見光光催化活性分析，探討本研究所製備之氮氧化鈦光觸媒之應用性。UV-visible DRS之分析顯示，本研究所製備之氮氧化鈦光觸媒，無論經由可見光或紫外光長期照射的環境下，其在可見光範圍之吸收效率皆不會造成太大影響；而可見光催化活性測試的結果顯示，受到可見光或紫外光的長期照射，會降低其光催化活性。但是經過可見光或紫外光照射150天後的氮氧化鈦光觸媒，其可見光之光催化活性效率表現，仍優於商業化二氧化鈦。證明本研究製備之氮氧化鈦光觸媒，具有良好的長期穩定性。

關鍵字

氮摻雜二氧化鈦 ； 光觸媒 ； 亞甲基藍 ； 光催化活性

並列摘要

Nitrogen-doped TiO2 would narrow bandgap, extend absorption region from UV-light to visible-light, and enhance photocatalytic activity under visible light. In our study, we prepared N-doped TiO2 photocatalysts with different urea concentrations by wetness impregnation. The crystal structures, chemical bonds and optical properties of photocatalysts of N-doped TiO2 were analyzed by X-ray diffraction (XRD), Electron spectroscopy for chemical analysis (ESCA), UV-visible diffuse reflectance spectra (UV-visible DRS), and photocatalytic activity of methylene blue solution under various light sources was estimated.
The photocatalytivity of different N-doped TiO2 photocatalysts prepared by wetness impregnation were compared with Degusa P25. N-doped TiO2 photocatalysts could enhance absorbed efficiency under visible light and shift absorption region from UV-light to visible-light. The experiments of photocatalytic activity test of methylene blue under visible light were shown that reaction constants (k) and photocatalytic activity of different N-doped TiO2 are superior to P25. The higher photocatalytic activity of 2 M N-doped TiO2 photocatalysts was prepared by the calcination process at 350 ℃ for 2 hours. Reaction constants of 0.0043 min-1 and photodegradation efficiency of 67.11 % for 6 hours under visible light were obtained. Reaction constants of 0.0067 min-1 and photodegradation efficiency of 71.53 % for 6 hours under BLED light were also determined.
The aging test of 2M N-doped TiO2 photocatalysts was performed under visible light and UV light irridation, respectively. Samplings of 2M N-doped TiO2 photocatalysts at various aging time were analyzed by UV-visible DRS and photocatalytic activity under visible light. According to the analysis of UV-visible DRS, the absorbed efficiency of N-doped TiO2 was not apparently varied under visible light or UV light irradiation. The photocatalytic activity efficiency of N-doped TiO2 irradiated under visible light or UV light for 150 days is still better than P25.

並列關鍵字

N-doped TiO2 ； photocatalyst ； methylene blue ； photocatalytic activity

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