| 摘要: | 本研究以噴霧熱解法將氧化鋅附著在二氧化鈦奈米粉體的表面形成結合型光觸媒。製備過程將市售二氧化鈦粉體P25加入與含檸檬酸之硝酸鋅水溶液，再以噴霧熱解法製得氧化鋅/二氧化鈦粉體。實驗裡探討了三種不同的ZnO附著量，其分別為Zn2+/TiO2莫耳比例0.03、0.003與0.0006。藉由熱重-熱差分析儀可得知有機物質的分解情形並可確定粉體後續熱處理的溫度，再利用傅立葉紅外線光譜儀分析有機物質的物種。溶液濃度與熱處理溫度對製得粉體物理性質之影響則藉由X-光繞射儀和BET比表面積儀等作其特性分析，並以掃描式電子顯微鏡觀察其型態(morphology)的異同。
光催化效能測試方面，製得之光觸媒分散於固定濃度之亞甲基藍水溶液中並以365nm之紫外光燈進行60分鐘的照射，藉由量測溶液中亞甲基藍濃度隨光照射時間之變化來瞭解其光催化效能。在相同反應觸媒表面積的比較基準下，Zn2+/TiO2莫耳比為0.003與0.0006在600℃與700℃下的ZnO/TiO2光催化反應速率常數(specific reaction rate)明顯優於P25，證明添加氧化鋅後的觸媒粉體可以有效提升其光催化效能。
ZnO/TiO2, a coupled photocatalyst, was prepared using a spray pyrolysis process. In preparation, P25 powder was uniformly dispersed in an aqueous solution of zinc nitrate and citric acid. The pH of the suspension was adjusted to 7 using NH4OH. Three different molar ratios of Zn2+/TiO2 (i.e., 0.03, 0.003, and 0.0006 ) in the suspension were used in this study to investigate the effects of ZnO contents on the photocatalytic performance of ZnO/TiO2 particles. The neutral suspension so obtained was then sprayed and contacted with an air flow of 250 ℃to undergo the evaporation of solvent and the decomposition of salts. The particles, collected using cyclone, were calcined in air at different temperatures. The resultant particles were characterized using XRD, FT-IR, SEM, EDS, BET, and TGA. To examine photocatalytic abilities of the prepared ZnO/TiO2 particles, the particles of 0.05g were dispersed in 250mL aqueous solution of methylene blue (10μM) and then irradiated by 365nm UV light. The concentration changes of MB(aq) with irradiation time were measured, using UV-VIS spectrometer, and kinectically analyzed to estimate the corresponding specific reaction rates. The results indicated that the ZnO/TiO2 particles prepared using Zn2+/TiO2 of 0.003 or 0.0006 and calcining at 600 or 700 ℃ exhibited better surface photoreactivities than that of P25. |
