离子液体存在下铜的电沉积及其表面增强拉曼散射效应研究

离子液体作为一种绿色介质,在电化学领域中的研究正在兴起,引起了研究者的浓厚兴趣。文章运用循环伏安法研究了离子液体(1-丁基-3-甲基咪唑四氟硼酸盐,bmim]BF4)存在时,酸性硫酸铜溶液中铜在铜电极上的电化学沉积行为。研究表明,bmim]BF4的加入使铜的沉积峰电位负移,沉积电流增加。采用扫描电镜(SEM)和X射线衍射(XRD)对铜镀层的形貌及结构进行表征,结果显示离子液体的存在可使铜镀层的层状晶粒尺寸减小,镀层出现(220)高择优取向。以甲基橙(MO)为探针分子,研究了所得铜镀层的表面增强拉曼散射(SERS)效应,发现离子液体存在下得到的铜镀层是较好的SERS基底,具有良好的增强效果及稳定性。对MO分子的增强因子可达4.7×105,而且保存了60天后,其检测灵敏度没有显著的降低。

Electrochemical deposition of copper by using ionic liquids as additive and its surface-enhanced Raman scatting effect

The use of room-temperature ionic liquids (RTILs) as green media for electrochemical application has attracted great attention recently. However, the effects of RTILs used as additives for electrodeposition of metals have hardly been explored. In the present work, the electrochemical deposition of copper was investigated on a pure copper plate from acid cupric sulfate solutions in the presence of RTILs (1-butyl-3-methylimidazolium tetrafluoroborate, bmim] BF4) additive by cyclic voltammetric technique, scanning electron microscope (SEM), and X-ray diffraction (XRD). For comparison, the electrodeposition of copper from acid cupric sulfate solutions was also investigated. The voltammograms showed that the cathodic peak potential shifted toward more negative potential and cathodic peak current increased when 1.0 x 10(-4) mol x L(-1) bmim] BF4 was added into acid cupric sulfate solutions. SEM images indicated that the shinning electrodeposits of copper were lamellar structure and the size of layered grain decreased with addition of bmim]BF4 additive. The XRD results indicated that copper deposits exhibited face-centered cubic structure and (220) highly preferred orientation. The surface-enhanced Raman scattering (SERS) activities of copper deposits were measured by using methyl orange (MO) as the probe molecules. The copper electrodeposit obtained in acid cupric sulfate solutions with bmim]BF4 is shown to be excellent substrate for SERS measurements, demonstrating significant enhancement and good stability. The enhancement factor was calculated to be up to 4.7 x 10(5). It was also found that copper electrodeposit stored for 60 days in air shows no significant degradation in its sensitivity.