界面活性劑輔助奈米金結構合成於碳電極

Abstract

本論文的研究乃在於利用簡易的賈凡尼置換反應(galvanic displacement reaction)，於溶液中添加十六烷基三甲基氯化銨(cetyltrimethylammonium chloride; CTAC)以合成片狀、花狀與線狀奈米金。實驗結果發現， CTAC的添加對於產物形態有著顯著的影響：如果溶液中沒有添加任何CTAC時，銅金屬與金氯酸水溶液中的AuCl4-離子會進行自發性的氧化還原反應得到片狀結構聚集的奈米金；加入CTAC 2.7 mM做為晶面成長控制劑時，結構變成花狀的奈米金；若再添加CTAC至 3.6mM時，產物形態轉變為[110]方向成長的線狀結構，線寬約15-25 nm，長度可達300 nm。若將金屬換成錫去還原金氯酸，加入界面活性劑CTAC也可以得到大量的奈米金線，其直徑大約分布在50-100 nm間，可達十幾µm，微結構鑑定顯示此線狀結構傾向延著[110]方向成長fcc的單晶結構。用此金線對於P-NTP (p-nitrothiophenol)，作表面加強拉曼訊號surface-enhance Raman scattering (SERS)應用，發現可以加強訊號強度約兩百倍。最後用電化學方式，加入金氯酸、CTAC及硝酸為反應溶液，通入1.5 V的電壓可以得到奈米珊瑚狀奈米金結構。

In this study, novel nanostructures of metal gold were discovered, including sheet, flower, wire and coralloid shapes. We demonstrated the synthesis of gold nanostructures via Galvanic displacement reaction. We found that cetyltrimethylammonium chloride (CTAC) played an important role to affect the morphology of the products. Au nanosheets, nanoflowers and nanowires were derived by using Cu metal as the reductant in the presence of CTAC on carbon electrodes. The diameters of single crystal Au nanowires, reducted from HAuCl4 by Cu metal, were 15-25 nm, and the lengths were 300-500 nm. Each nanowire exhibited single crystallinity with the growth in [110] orientation. In addition, Au nanowires, diameters 50-100 nm and lengths up to several tens μm, were prepared by reacting HAuCl4(aq) with Sn metal and CTAC on a carbon electrode. Furthermore, surface-enhance Ramen scattering (SERS) spectra of P-NTP (p-nitrothiophenol) on the as-prepared carbon electrode with gold nanowires was measured. We also used electrochemical synthesis method to produce gold nanocoralloid.