- 學位論文
以非金屬氮、磷共摻雜二氧化鈦之製備、特性及光催化應用研究
Preparation, Characterization, and Photocatalytic Application of Non-metallic Nitrogen and Phosphorus Co-doped Titanium Oxide
摘要
二氧化鈦是一種n型半導體光觸媒，其能帶為3.2 eV，必須照射＜387.5 nm的紫外光波才能使其激發以降解有機汙染物，但太陽光中通常只有不到4%的紫外光，因此，本研究實驗利用摻雜非金屬氮、磷元素改質二氧化鈦的能帶結構，製備可見光光觸媒。實驗利用溶膠─凝膠法以四異丙氧基鈦、氨水以及六氟磷酸銨作為改質二氧化鈦的前驅物，製備三種不同摻雜方式的氮、磷共摻雜二氧化鈦奈米粉體，再將光觸媒粉體在空氣中以不同溫度煅燒後，透過X-ray繞射儀 (XRD) 、拉曼光譜儀 (Raman) 、X-ray光電子光譜儀 (XPS) 、反射式紫外─可見光光譜儀 (UV-VIS) 和掃描式場發射電子顯微鏡 (FE-SEM) 進行粉體表面特性分析；此外，光觸媒的光催化活性則是以亞甲基藍溶液在可見光照射下的光降解脫色率進行測試。在XRD和Raman的結果顯示，三種氮、磷共摻雜二氧化鈦奈米微粒在未煅燒時為不定型態，在400~800 oC煅燒後皆為銳鈦礦相，且樣品粉體微粒的平均粒徑分別大約在19~30 nm、17~33 nm及10~32 nm之間；XPS結果顯示，光觸媒樣品在經過400 oC以上高溫煅燒後氮原子部分進入晶格中取代二氧化鈦的氧原子，而磷則是以P5+存在於二氧化鈦晶體表面；UV-VIS結果顯示，樣品在390~550 nm之間存在可見光吸收峰，且隨著煅燒溫度上升，可見光吸收峰減少。光催化活性測試結果顯示，三種氮、磷摻雜改質光觸媒 (N, P/TiO2) 在可見光照射之下對亞甲基藍溶液的光催化活性比商品UV-100、P-25以及N/TiO2、P/TiO2的光催化活性高。
並列摘要
Titanium dioxide (TiO2) is an n-type semiconducting photocatalyst. It can be activated to decompose the organic pollutants under UV light of wavelengths < 387.5 nm irradiation because of its large band gap of 3.2 eV. But the solar spectrum usually contains about 4% UV light. Consequently, in this study we describe the preparation of visible-light responsed photocatalysts with non-metallic nitrogen and phosphorus modified TiO2. Three series of nitrogen and phosphorus co-doped titanium oxide nanoparticles were obtained by a simple modified sol-gel method using ammonium hydroxide and ammonium hexafluorophosphate as the N and P sources. These modified samples were then calcined in air at different temperatures for 5h. The results were characterized by X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS), UV-VIS spectroscopy and Scanning electron microscope (SEM). The photocatalytic activity was evaluated by the degradation of methylene blue (MB) under visible light. From the surface chemistry investigations of XRD, Raman, XPS, UV-VIS and SEM, the results showed that the particle size of N, P co-doped TiO2 were about 19~30 nm, 17~33 nm and 10~32 nm, respectively. The samples calcined above 400 oC were all anatase structure. N atoms replaced a part of oxygen sites in the TiO2 lattice and P atoms only existed in a pentavalent-oxidation state. The samples exhibited a absorption shoulder between 390~550 nm that the calcination temperature leads to a lowering amount of visible absorption. Furthermore, compared with Hombikat UV-100, Degussa P-25, N/TiO2 and P/TiO2, the N, P/TiO2 samples have a batter response of visible light.