导电聚吡咯膜电极的现场电化学-ESR研究

ESR-electrochemical Studies of Electrodes Coated with Conducting Polypyrrole Film

关于导电聚吡咯（PP）膜的导电机理，文献上提出的“极化子－双极化子”模型引起了电化学学者的兴趣，该模型认为PP在一定条件下可产生带一个正电荷的极化子（S＝1／2）和带两个正电荷的双极化子（S＝0）。Scott等人通过ESR研究认为导电PP中担负电荷传 的主要带电物种是双极化子。Genoud等人则用电化学现场的ESR方法研究PP膜电极在有机溶液中的电化学过程，揭示自旋与电荷载流子之间存在的相互关系，认为极化子在导电机理中的作用仍需进一步研究。本文报道PP膜电极在水溶液中电化学－ESR行为，定性地探讨了电位、电量对PP膜中极化子形成与转化过程的影响，并在PP膜／溶液存在电化学反应情形下，考察了PP膜中可能的电荷传输机理。

Electrodes coated with conducting polypyrrole film have been studied in aqueous solutions by in-situ ESR-electrochemical measurements. It is qualitatively showed that the spin concentration is directly dependant on the oxidation state of polypyrrole. It is also indicated that, in tansient process, the formation of spins and their transformation to spinless structures are correlative with electrochemical oharge injections. The experimental results are explained in terms of polaron and bipolaron formations in the electrochemical redox processes. ESR-electrochemical behaviours of the polymer-coated electrodes in solutions containing ascorbic acid have also been investigated. It is believed that the charge transfers in polypyrrole film might include contributions from both polarons and bipolarons.