利用特斯拉線圈驅動大氣微電漿之金屬奈米顆粒合成

Abstract

由於金屬奈米顆粒具有獨特的光學特性，已被廣泛應用在各領域。在過去有文獻指出大氣電漿產生的電子與活性物質可作為還原劑來合成金屬奈米顆粒，其中常被使用的大氣電漿種類為直流微電漿，但雙電極構造限制顆粒在表面圖案化的應用。由於特斯拉線圈可產生高電壓，故能作為驅動電漿形成的裝置，且具有單電極優勢，但至今尚未被應用在合成金屬奈米顆粒。因此在本研究中，提出以特斯拉線圈驅動大氣微電漿的方法在溶液中合成金與銀奈米顆粒，討論陰、陽、非離子界面活性劑與製程參數對顆粒形態的影響，並提出一種在表面原位合成金屬奈米顆粒的技術。 實驗結果顯示溶液未添加界面活性劑時，金與銀奈米顆粒傾向聚集在氣-液界面形成薄膜，有添加界面活性劑則可促進顆粒在溶液內部形成。在氯金酸溶液含有陰離子型界面活性劑(SDS)與非離子型界面活性劑(Triton X-100)的金奈米顆粒形貌為圓形;含有陽離子型界面活性劑(CTAC)的金奈米顆粒形貌則為圓形、三角形、棒狀，此非等向性的生長可應用於設計形狀多樣化的顆粒。 相較於奈米顆粒在溶液中合成，由於紙上可提供的成核點數目較多，加上電漿造成的局部高溫，使顆粒能在表面快速生成。此種直接書寫的方法未來可應用於奈米顆粒在固體表面圖案化的製備。

Metal nanoparticles have been widely utilized in various fields due to their unique optical property. In the past, many studies reported that electrons and reactive species generated by atmospheric plasma could be used as reducing agents to synthesize metal nanoparticles. The most commonly used type of atmospheric plasma for synthesizing metal nanoparticles is DC microplasma, but the dual-electrode structure limits the application of particles patterning on the surface. Since Tesla coil can generate high voltages, it could be used as a power source for driving plasma generation and has the advantage of single electrodes. However, Tesla coil has not yet been used in the synthesis of metal nanoparticles to date. Therefore, in this study, a method of driving atmospheric microplasma by Tesla coil is proposed to synthesize gold and silver nanoparticles in the solution. The effects of anionic, cationic, nonionic surfactants and process parameters on the particle morphology are also discussed. The results show that without surfactant, gold and silver nanoparticles tend to aggregate at the gas-liquid interface to form a thin film. The addition of surfactant can promote the formation of particles in the solution. The morphology of gold nanoparticles in anionic surfactant (SDS) and nonionic surfactant (Triton X-100) solution is spherical; the morphology of gold nanoparticles in cationic surfactant (CTAC) solution includes spherical, triangular, and rod-like shape. This anisotropic growth could be applied to design diverse shapes of nanoparticles. In addition, we develop a technique for in-situ synthesis of metal nanoparticles on the solid surface. Compared with nanoparticles synthesizing in the solution, fabrication of nanoparticles on the paper surface is faster due to large amounts of nucleation site on the solid surface and local high temperature caused by the plasma. This direct-writing method could be used for patterning nanoparticles on the solid surface.