Glassy carbon electrodes I. Characterization and electrochemical activation
Glassy carbon electrodes I. Characterization and electrochemical activation
复制标题
DOI：
10.1016/s0008-6223(00)00228-1
复制
发表时间：
2001-01-01
期刊：
影响因子：
10.9
通讯作者：
Jovanovic, VM
中科院分区：
文献类型：
--
作者：
Dekanski, A;Stevanovic, J;Jovanovic, VM
研究了两种类型的玻璃碳电极的电化学性质，一种在1000 ℃下热处理（样品K），另一种在2500 ℃下热处理（样品G）。机械抛光或电化学极化的电极，其特征在于在NaOH，HClO 4，和H2SO 4的解决方案，通过循环伏安法（CV）在不同的扫描速率之间的电位范围内的氢和氧的演变。电极的活性取决于所检查的玻璃碳的性质，如通过热处理的温度和样品的机械或电化学预处理来确定的。注意到，当抛光时，两种类型的电极在增加溶液的pH值时表现出双层电荷的增加。对于这两种类型的样品，CV电荷在阳极极化后增加。氧化电位越高，电荷增加越明显，特别是在酸性溶液中。在酸性溶液中，经阳极极化的玻碳表面的电荷量从抛光的低于1 mC cm（-2）增加到几百mC cm（-2）。对伏安电荷以及电极表面形态变化对氧化时间的依赖性的分析表明，电化学活化过程存在三个阶段。第一个只在激活开始时发生一次，而另外两个重复发生，反映了周期性的激活和去激活过程。这些阶段进行了讨论，并归因于表面层氧化，氧化石墨层的生长和表面的机械破坏。通过AES、XPS和STM的独立表面分析证实了通过电化学方法获得的结果。(C)2001爱思唯尔科技有限公司版权所有。
Electrochemical properties of glassy carbon electrodes of two types were examined, one thermally treated at 1000 degreesC (sample K) and another thermally treated at 2500 degrees (sample G). Mechanically polished or electrochemically polarized electrodes were characterized in NaOH, HClO4, and H2SO4 solutions by cyclic voltammetry (cv) at different sweep rates in the potential range between the hydrogen and oxygen evolution. The activity of the electrodes depended on the properties of the glassy carbon examined, as determined by both the temperature of thermal treatment and the mechanical or electrochemical pretreatment of the sample. It was noticed that both types of electrodes, when polished exhibited an increase in the double layer charge upon increasing the pH value of the solution. The cv charges, for both types of samples, increase upon anodic polarization. The higher the potential of oxidation, the more pronounced is the increase in charge, particularly in acidic solution. The increase in charge amounts from below I mC cm(-2) for polished glassy carbon up to few hundreds of mC cm(-2) for surfaces anodically polarized in acidic solution. Analysis of the dependence of voltammetric charge, as well as morphological changes of the electrode surface, on the time of oxidation suggests the existence of three stages in the electrochemical activation process. The first one occurs only once at the beginning of the activation, while the other two repeat themselves, reflecting a periodical activation and deactivation process. These stages were discussed and ascribed to a surface layer oxidation, graphite oxide layer growth and mechanical destruction of the surface. Independent surface analysis by AES, XPS and STM confirms the results obtained by electrochemical methods. (C) 2001 Elsevier Science Ltd. Al rights reserved.