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/solution" interfaces in terms of ion distribution, electrical double layer structure and polarization behaviors. Due to the complexity of the APE and the associated solid-solid interfaces, fundamental investigations are challenging and deeper understanding of the structure 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) of the electrode/QAPPT (quaternary ammonia poly (Nmethyl-piperidine-co-p-terphenyl) interface. Cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and microelectrode-based immersion technique are employed. The differential capacitance curves of Pt/QAPPT interfaces exhibit an asymmetric U-shaped feature with a minimum at the potential which is consistent with the PZTC measured by the immersion method. The capacitance rises less quickly on the negative than 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.
alkaline polymer electrolyte, microelectrode, differential capacitance curve, potential of zero charge, double layer structure
Chen-Xi Liu, Ze-Ping Zou, Mei-Xue Hu, Yu Ding, Yu Gu, Shuai Liu, Wen-Jing Nan, Yi-Chang Ma, Zhao-Bin Chen, Dong-Ping Zhan, Qiu-Gen Zhang, Lin Zhuang, Jia-Wei Yan, Bing-Wei Mao. The Determination of PZC and Differential Capacitance Curve of Platinum-Alkaline Polymer Electrolyte Interfaces[J]. Journal of Electrochemistry, doi: 10.13208/j.electrochem.2303151.