碳纤维微电极恒电位活化及测定金属离子的研究

碳纤维微电极已被广泛应用于电化学研究和分析测定,该电极尺寸极小,在分析性能上与常规电极有显著不同,在不镀汞的情况下,用碳纤维电极直接测定金属离子几乎没有明显的伏安响应,本文提出用+2.5 V恒电位预先活化碳纤维电极,使测定灵敏度大为提高,在双电极体系和静止溶液中,采用溶出伏安法可测定10~(-9)级金属离子,以同样的方法清洗电极,测定结果重现性良好,由于分析过程中不使用汞,该电极的测定范围大大增加,特别是用于氧化还原电位较正的金属离子测试,根据循环伏安法、扫描电镜和电子能谱的研究,发现碳纤维表面状况在处理前后有很大变化,并与测定灵敏度密切相关。

Potentiostatic Activation of the Carbon Fiber Electrode and Its Application to the Determination of Metal Ions

Carbon fiber electrodes subjected to potentiostatic pretreatment exhibit electrochemical activity. The activated electrodes can be used for determining metal ions directly without mercury film. The pretreated carbon fiber electrode shows a high sensitivity and good reproducibility in stripping voltammetry. The detection limits for Cd, Pb and Bi are 0. 5, 0. 2 and 0. 8 ng/mL respectively. The activation conditions are optimized and activation mechanism is explored by means of cyclic voltammetry , scanning electron microscopy and X-ray photoelectron spectroscopy.