二氧化鈦是一種具半導體性質的觸媒，利用紫外光照射可進行污染物的光催化分解反應，本研究以摻雜過渡金屬離子於二氧化鈦中減小二氧化鈦能隙，增加二氧化鈦對可見光的吸收能力，再利用波長為419nm的光源進行水楊酸的光催化分解反應。 利用溶膠凝膠法合成二氧化鈦，在水解反應過程中添加Cr3+、Fe3+與V4+等過渡金屬離子於二氧化鈦中，製備完成的鍍膜溶液為穩定懸浮狀態，經1~2個月的静置也不會沉澱，當鍛燒溫度為200℃時，二氧化鈦與摻雜過渡金屬離子之二氧化鈦的晶型主要為anatase，摻雜過渡金屬離子的二氧化鈦中，以摻雜釩離子對可見光的吸收能力最好。 利用浸漬鍍膜法將二氧化鈦鍍在玻璃基材上，以水楊酸水溶液進行可見光光催化分解反應，結果發現摻雜鉻、鐵離子的二氧化鈦可見光光催化效果，相較於二氧化鈦相當或稍高，摻雜釩離子的二氧化鈦光催化活性最弱，原因是釩離子最易進入到二氧化鈦晶格中，而過渡金屬離子進入到二氧化鈦會導致二氧化鈦結晶形成缺陷，使電子電洞在缺陷中再結合，因而降低光催化反應活性。 Abstract Titanium oxide is a semi-conducting photocatalyst. It can decompose the pollutants by irradiation of UV light. This study attempted to decrease the band-gap of TiO2 in order to improve the optical absorption properties in visible region. Photo-decomposition of salicylic acid under irradiation of visible light (419nm) was studied. Titanium oxide was synthesized by sol-gel method. The transition metal ions modified TiO2 were synthesized by adding transition metal ions Cr3+、Fe3+ and V4+ during the hydrolysis reaction of TiO2. The suspension of nanocrystalline TiO2 are stable after 1~2 months. The crystalline structures of TiO2 and modified TiO2 are anatase after annealing at 200℃. Titanium oxide modified with V4+ ions absorbs more visible light. Solutions containing titanium oxide were coated on glass by dip-coating method. The photo-decomposition activities of Cr3+ and Fe3+ modified TiO2 were similar to or higher than TiO2. The photo-decompo -sition activity is lowest over V4+ modified TiO2. The V4+ ions incorporated into TiO2 crystals may cause defects in TiO2 crystal and photo-decomposition activities decrease by recombination of electrons and holes at the defect sites.
