Pt與In2O3之修飾對於TiO2奈米線之光催化性質的影響

Abstract

透過結合不同能帶結構的半導體奈米晶體能提供許多的優點，如:更寬廣的吸收範圍、降低光漂白現象、能夠調控的能階和改善光電的轉換效率。在此論文中，我們透過沉積-鍛燒的方法成功合成出氧化銦修飾的銳鈦礦二氧化鈦奈米線 (In2O3-TiO2 NWs)。由於氧化銦和二氧化鈦能帶結構的差異，使此複合材料能產生載子轉移，造成電子電洞對的分離。In2O3-TiO2 奈米線內的載子分離特性，也展現在其降解染料的光催化的特性上。相較於商用的P-25 TiO2粉末和利用物理方式混合的In2O3-loaded TiO2 NWs，In2O3-TiO2 NWs 在紫外光的照射下，展現出更佳的光催化特性。為了更進一步提升其光催化活性，適量的Pt奈米粒子也被用來修飾在In2O3-TiO2 NWs上。這樣的提升是來自於在修飾Pt到二氧化鈦表面上之後，增加了電子由In2O3傳遞到TiO2的驅動力。而且在自然陽光的照射下，顯示出In2O3-TiO2-Pt NWs 能接收陽光中的能量進行高效率的光催化反應。電子在In2O3, TiO2和Pt的轉移現象，我們也透過其相對的光電流量測和時間解析螢光光光譜來探討分析。

Combination of semiconductor nanocrystal (NCs) with different band structures has been extensively explored since a lot of advantages may be offered by this composite system, for example, the wide absorption profile, the enhanced resistance to photobleaching, the continuous tunability of energetic levels, and the improved photoelectric conversion efficiency. In this thesis, we successfully synthesized In2O3-decorated anatase TiO2 nanowires (In2O3-TiO2 NWs) through a simple precipitation-annealing process. The difference in band structures between In2O3 and TiO2 provided charge carriers with another preferential route for charge transfer, resulting in the separation of photoexcited electrons and holes. The charge carrier separation in In2O3-TiO2 NWs was revealed with their photocatalytic decomposition toward an organic dye. As compared to the commercial P-25 TiO2 powder and In2O3-loaded TiO2 NW samples, the as-synthesized In2O3-TiO2 NWs exhibited superior photocatalytic efficiency under UV illumination, demonstrating their potential as an efficient photocatalyst in relevant redox reactions. A further enhancement in the photocatalytic activity of In2O3-TiO2 NWs can be achieved when Pt nanoparticles of suitable amount were deposited on the surface of TiO2. This improvement is due to the increasing driving force of electron transfer from In2O3 to TiO2 achieved by the decoration of Pt on TiO2 surfaces. Furthermore, the result of performance evaluation under natural sunlight shows that the present In2O3-TiO2-Pt NWs can be used as highly efficient photocatalysts which may practically harvest energy from sunlight. The electron transfer event among In2O3, TiO2 and Pt was also characterized with the corresponding photocurrent measurement and time-resolved PL spectroscopy.