Laforgue Alexis, Addou Tania, Bélanger Daniel
Département de Chimie, Université du Québec à Montréal, Case Postale 8888, succursale Centre-Ville, Montréal, Québec, Canada H3C 3P8.
Langmuir. 2005 Jul 19;21(15):6855-65. doi: 10.1021/la047369c.
The deposition of 4-X phenyl groups (X = NO2, COOH, N-(C2H5)2) on polycrystalline gold electrode was achieved by the electrochemical reduction of the corresponding 4-substituted phenyldiazonium tetrafluoroborate salts in anhydrous acetonitrile media. The electrochemical quartz crystal microbalance measurements evidenced a two-step deposition process: the first one is the deposition of close to a monolayer and the second one is the relatively slower growth of multilayers. In this second region, the deposition is less efficient than for the first one. The electrochemical behavior of the resulting modified gold electrode was investigated in the presence of an electroactive redox probe and these results, together with the electrochemical quartz crystal microbalance data, demonstrated significant differences in reactivity and in deposition efficiency between the diazonium salts. The characterization of the modified electrodes by cyclic voltammetry and electrochemical impedance spectroscopy, as well as X-ray photoelectron spectroscopy measurements, showed that the formation of multilayers is possible and that a significant fraction of the deposited material remained at the electrode surface, even following ultrasonic treatment. The X-ray photoelectron spectroscopy data indicate that the existence of Au-C and Au-N=N-C linkages (where C represents a carbon atom of the phenyl group) is uncertain. Nonetheless, the deposition of the aryl groups by electrochemical reduction of diazonium cations yielded a film that adheres well to the gold surface and the deposited organic film hindered gold oxides formation in acidic medium.
通过在无水乙腈介质中对相应的4-取代苯基重氮四氟硼酸盐进行电化学还原，实现了4-X苯基（X = NO2、COOH、N-(C2H5)2）在多晶金电极上的沉积。电化学石英晶体微天平测量证明了一个两步沉积过程：第一步是接近单层的沉积，第二步是多层相对较慢的生长。在第二个区域，沉积效率低于第一个区域。在存在电活性氧化还原探针的情况下研究了所得修饰金电极的电化学行为，这些结果与电化学石英晶体微天平数据一起表明，重氮盐之间在反应性和沉积效率上存在显著差异。通过循环伏安法、电化学阻抗谱以及X射线光电子能谱测量对修饰电极进行表征，结果表明多层的形成是可能的，并且即使经过超声处理，仍有很大一部分沉积材料留在电极表面。X射线光电子能谱数据表明，Au-C和Au-N=N-C键（其中C代表苯基的碳原子）的存在不确定。尽管如此，通过重氮阳离子的电化学还原沉积芳基得到了一种与金表面粘附良好的膜，并且沉积的有机膜在酸性介质中阻碍了金氧化物的形成。
