电极/碱性聚电解质界面的微分电容曲线和零电荷电位测定

The Determination of PZC and Differential Capacitance Curve of Platinum-Alkaline Polymer Electrolyte Interfaces

碱性聚合物电解质作为现代碱性氢氧燃料电池的核心组成部分,其单离子导体的特性使得“电极/碱性聚电解质”界面的性质与“电极/溶液”界面有所不同。本文使用微电极,运用循环伏安、电化学交流阻抗以及浸入法等方法,测定了电极/碱性聚电解质界面的微分电容曲线和零电荷电位。该界面的微分电容曲线呈“U”状,且存在局域极小值,该极小值所对应的电位与浸入法测得的零电荷电位数值一致。单离子导体的特性使得“电极/碱性聚电解质”界面在零电荷电位两侧表现出不同的电化学极化行为。

Alkaline polymer electrolyte(APE)is the core component of modern alkaline hydrogen and oxygen fuel cells,and its single ion conductor nature makes the“electrode/APE”interfaces different from the conventional“electrode/so-lution”interfaces in terms of ion distribution,electrical double layer structure and polarization behavior.Due to the complexity of the APE and the associated solidesolid interfaces,fundamental investigations are challenging and deeper understanding of the structures and properties of such interfaces is in the infant stage.In this work,we aim to investigate the double layer structure from the aspects of differential capacitance curve and potential of zero charge(PZC)at the electrode/QAPPT(quaternary ammonia poly(Nmethyl-piperidine-co-p-terphenyl)interface.Cyclic vol-tammetry,electrochemical impedance spectroscopy(EIS)and microelectrode-based immersion techniques were employed.The differential capacitance curves of Pt/QAPPT interfaces exhibited an asymmetric U-shaped feature with a minimum at the potential which is consistent with the PZTC measured by the immersion method.The capacitance raised less quickly on the negative than the positive sides of the PZTC.These results reflect the characteristics of the single ion conductor and role of alkaline polyelectrolytes in modifying the double layer structure of the electrode/APE interfaces.