鐵、鎳摻雜與負載之二氧化鈦奈米粒子於光催化活性及水裂解之應用

Abstract

在本人的研究中，主要探討鐵鎳金屬摻雜和還原於二氧化鈦奈米粒子的影響，而在摻雜的模式上，本人測試了單一金屬摻雜和共摻雜的方式，並對光催化有機染料降解和水裂解產氫做系統上的討論，此外，並針對氫化金屬摻雜和金屬還原奈米材料的影響作一系列的研究。 在奈米材料的合成上，本人利用alcohol-thermal法與聯胺還原法，合成金屬摻雜或金屬還原於二氧化鈦的樣品，除了染料降解與水裂解的測試外，並藉由XRD、SEM、XPS、UV-Vis光譜分析樣品組成。 在UV-Vis光譜鑑定分析中顯示出氫化後的奈米材料有效增強太陽光譜中的可見光區域，而對於鎳摻雜二氧化鈦的樣品上，氫化後的產氫速率比未氫化的增加了4.5倍，且值得注意的是，它比氫化或未氫化的純二氧化鈦增加了18倍，其中最為顯著的是使用商用二氧化鈦(P-25)作為鎳還原前驅物的樣品，氫化後比未氫化的產氫速率上增加了20倍左右，而與氫化或未氫化的純二氧化鈦比較，更高達67倍，另外，根據GC/MS的測量結果，利用2瓦的氙燈照射下，氫化後的鎳摻雜二氧化鈦奈米粒子與鎳還原二氧化鈦奈米粒子，總產氫量分別為1.64 mmol/g-hr 和6.18 mmol/g-hr，而與上述結果相反的是，鐵金屬不管摻雜或還原於二氧化鈦，甚至與鎳共摻雜等，在染料降解與水裂解上都展現出極弱的光催化能力。

In this work the effects of doping and loading TiO2 nanoparticles (NPs) with Ni and Fe, individually or co-operatively, on their photo-catalytic activities in the degradation of organic dyes and water splitting generating hydrogen have been investigated systematically. In addition, the effect of hydrogenation of these metal-doped and metal-loaded nano-materials on water splitting and dye degradation has been studied. These new metal-doped and metal-loaded nano-materials were synthesized by the alcohol-thermal method and the hydrazine reduction method, respectively, and characterized with different analytical techniques including XRD, SEM, XPS, and UV-Vis absorption spectroscopy, in addition to the dye degradation and water splitting measurements. The results of the UV-Vis absorption measurements showed that the hydrogenation of these nano-materials led to a significant enhancement in the absorption in the visible region of the solar spectrum. For the Ni-doped TiO2, the hydrogenation increased the H2 production rate over that of the doped NPs by 4.5 times and, notably, more than those of the pure TiO2 NPs or the hydrogenated TiO2 NPs without doping by as much as 18 times. Most significantly, the hydrogenation of the Ni-loaded TiO2 NPs using the commercial P25 NPs led to a factor of 20 enhancement in H2 production over that of the sample without hydrogenation and as much as 67 times over that of pure TiO2 or hydrogenated TiO2 without Ni-loading. Based on the results of GC/MS measurements, the rates of H2 generation from the photolysis of the Ni-doped TiO2 NPs and the hydrogenated Ni-loaded TiO2 NPs are, respectively, 1.64 mmol/g-hr and 6.18 mmol/g-hr employing about 2 W of a xenon lamp. Contrary to above results, the Fe-doped or loaded TiO2 NPs as well as those co-doped with Ni revealed much weaker photo-catalytic activities in dye degradation and water splitting tests.