表面活性剂对聚氯乙烯膜修饰电极电化学行为的影响

采用循环伏安法考察了所制备的聚氯乙烯(PVC)膜修饰电极的稳定性,结果表明,该修饰电极性能稳定,电极反应过程为扩散控制的过程。以循环伏安法、计时库仑法、稳态极化曲线法和交流阻抗法分别考察了阳离子(十六烷基三甲基溴化铵,CTMAB)、阴离子(十二烷基硫酸钠,SDS)和非离子(脂肪醇聚氧乙烯醚,AEO9)3种不同类型的表面活性剂对PVC膜-Ag[B(ph)4]修饰电极反应过程的影响。结果表明:加入CT-MAB或SDS后,PVC膜中Ag[B(ph)4]氧化态和还原态的扩散系数分别比电极在0.1mol/LKOH支持电解质中的扩散系数小,PVC膜修饰电极的反应过程受扩散控制的特征变得更明显,表明在此条件下膜中的电子转移速度加快,CTMAB或SDS对PVC膜修饰电极的电极反应过程有增敏作用。而加入AEO9后,PVC膜中的Ag[B(ph)4]氧化态和还原态的扩散系数比电极在0.1mol/LKOH支持电解质中的扩散系数大,并使电极反应的控制步骤从扩散控制转向含电子转移控制的扩散控制,表明在此条件下膜中的电子转移速度变慢,AEO9对PVC膜修饰电极的电极反应过程有抑制作用。

Effect of Surfactants on the Electrochemical Behaviors of Polyvinyl Chloride Membrane Modified Electrode

The electrochemical behaviors of a polyvinyl chloride (PVC) membrane modified electrode were investigated with cyclic voltammograms in 0.1 mol/L KOH solution. The results showed that the modified electrode was stable and the diffusion controlled electrode reaction was observed. In addition, cyclic voltammograms, chronoamperometry, the steady state polarization curves and alternative current impedance spectroscopy were used to study the effect of cationic (ethylrimethylammonium bromide, CTMAB), anionic (sodium dodecylsulfate, SDS) and nonionic (alkyl polyethoxyate, AEO9) surfactants on the electrochemical behaviors of modified electrode. Experimental results revealed that when CTMAB or SDS was added into 0.1 mol/L KOH solution, the diffusion coefficients of both oxidation and reduction forms of Ag [B(ph)4] in the membrane of PVC were decreased and the characteristics of the diffusion controlled electrode reaction were strengthened, which indicated that the rate of electron transfer in PVC membrane was increased. However, when AEO9 was added into 0.1 mol/L KOH solution, the diffusion coefficients of both oxidation and reduction forms of Ag[B(ph)4] in the film of PVC membrane were increased and the characteristics of the diffusion controlled electrode reaction were weakened, which indicated that the rate of electron transfer in PVC membrane was decreased. Therefore, cationic and anionic surfactants could enhance the electrode reaction of the PVC membrane modified electrode. Whereas, the nonionic surfactants could restrained the electrode reaction of the PVC membrane modified electrode.