硒奈米晶體之成長控制與其光電特性研究

Abstract

在此論文中，我們成功地利用CMC聚醣分子作為軟性模版以還原出高品質之硒奈米棒，並且系統性地探討硒奈米晶體之成長機制。我們證實CMC分子會形成類一維結構，並包覆於硒奈米晶體周圍，使硒晶體進行非等向性成長而形成一維奈米棒。在此合成系統中，硒奈米晶體之形貌與尺寸可藉由相關反應條件之操控來調整，例如pH值、反應溫度、CMC濃度、還原劑種類與還原劑濃度還原等。經由將銀離子加入硒奈米晶體溶液，可直接將銀置入硒晶體中而形成硒化銀奈米棒，此硒化銀奈米棒可進一步被使用於陽離子交換反應中，進而合成出硒化鎘和硒化鋅之奈米棒。與此系統中所製備之硒奈米棒，乃展現出優異之光導特性，說明了其可應用在光電開關裝置上的潛能；再者，硒奈米棒在紫外光照射下對亞甲基藍分子之降解展現出相當高的光催化活性，這也意味著硒奈米棒可能成為一個可多方面應用的光催化材料。

In this thesis, we successfully synthesized high-quality Se nanorods through a CMC-assisted chemical reduction approach. The growth mechanism for Se nanorods was systematically studied and discussed. We demonstrated that CMC molecules formed quasi-1-D channels that surrounded Se nanocrystals, enabling the occurrence of anisotropic growth of Se to form nanorods. Control over the resulting morphology of Se can be achieved through carefully modulating the relevant reaction conditions such as the pH value, reaction temperature and concentrations of CMC and reducing agents. Through the direct incorporation of Ag+ into Se, Ag2Se nanorods could be readily obtained. In addition, cation-exchange reaction was performed on the as-synthesized nanorods of Ag2Se, resulting in the formation of CdSe and ZnSe nanorods. The photoconductive properties of the as-synthesized Se nanorods were characterized, demonstrating their potential application in optoelectronic switching devices. Furthermore, the as-obtained Se nanorods showed considerably high photocatalytic activity for MB degradation under UV light illumination, implying that they could be a good photocatalyst toward many species.