二氧化鈦奈米線連接二氧化鈦奈米管陣列複合結構之製備及其光觸媒性質

Abstract

本研究使用簡單、製作成本低廉的陽極氧化法製備二氧化鈦奈米線連接二氧化鈦奈米管陣列複合結構(TNWs/TNAs)，主要探討製作過程中電鍍時間與電解液中的水含量對TNWs/TNAs形貌的影響。較長的電鍍時間會製備出較厚的二氧化鈦薄膜、較大奈米管直徑與較長的奈米線。另一方面，較多的水含量會製備出較薄的二氧化鈦薄膜、較大的奈米管直徑與較短的奈米線。 我們也同時藉由控制電鍍時間與電解液中的水含量製備不同TNWs/TNAs厚度與奈米線長度，並探討其光降解甲烯藍溶液的能力。在本實驗中厚度為10.5 μm、奈米管直徑為75 nm、奈米線長度為2.5 μm的TNWs/TNAs薄膜因為有較大的比表面積因此有最好的光觸媒活性。 最後我們將TNWs/TNAs與二氧化鈦奈米顆粒比較，發現雖然奈米顆粒有較大的比表面積但光觸媒反應速率較低，這是因為TNWs/TNAs提供直接的載子傳輸路徑降低電子電洞再結合機率而提升了光觸媒活性。另一方面，TNWs/TNAs也比懸浮在水中的奈米顆粒容易回收再利用，因此TNWs/TNAs是一種適合用在水淨化的光觸媒材料。

TiO2 nanowires on TiO2 nanotubes arrays (TNWs/TNAs) were fabricated by anodic oxidation, which is simple and low-cost. The anodizing time and the water content in the electrolyte for the effect of morphology were investigated in this thesis. The longer anodizing time would fabricate the thicker TiO2 film, larger TNAs diameter and longer TNWs. On the other hand, more water content in the electrolyte would fabricate the thinner TiO2 film, larger TNAs diameter and shorter TNWs. We also controlled the anodizing time and water content to fabricate various thicknesses of TNWs/TNAs films and different lengths of TNWs, and we further discussed their ability to photodegrade methylene blue (MB). In this research, TNWs/TNAs film with 10.5 μm film thickness, 75 nm TNAs diameter and 2.5 μm TNWs length has best photocatalytic activity due to their larger surface area. Finally, we compared with TNWs/TNAs and TiO2 nanoparticles (Degussa, P-25) film, though the surface area of nanoparticles is larger than TNWs/TNAs, the ability of photocatalysis is worse than TNWs/TNAs because TNWs/TNAs provide direct carriers diffusion path, which reduces the probability of recombination, and thus result in promotion of photocatalytic performance. On the other hand, TNWs/TNAs are easier retrieve and re-use in comparison with particles which suspend in the reaction water. Therefore, TNWs/TNAs are a suitable photocatalyst for use in the water purification.