Electrode polarization measurements in the FeSrCe_0.95Yb_0.05O_2.975Au proton conducting solid electrolyte cell

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• 作者：G. Pekridis ; K. Kalimeri ; N. Kaklidis ; C. Athanasiou ; G. Marnellos
• 关键词：Electrode polarization ; Proton conductor ; SCY ; Overpotential ; Fe ; Limiting current ; Exchange current ; Charge transfer reaction mechanism
• 刊名：Solid State Ionics
• 出版年：2007
• 期刊代码：96_01672738
• 类别：ch
• 出版时间：April 2007
• 卷：178
• 期：7-10
• 页码：649-656
• 文件大小：409 K

摘要

The effect of hydrogen partial pressure (1.3–5.8 kPa) and cell temperature (600–800 °C) on the kinetics and mechanism of the charge transfer electrode reaction taking place at the three phase boundary H₂–Fe–SCY (SCY = SrCe_0.95Yb_0.05O_2.975), was thoroughly examined by performing electrode polarization measurements. A three electrode single chamber proton conducting solid electrolyte cell of the type Fe–SCY–Au, was used in order to conduct the electrode kinetic studies. The steady-state current–overpotential characteristics were analysed with the high field approximations of the Butler–Volmer equation, by taking into account the presence of limiting currents. Both, apparent exchange current density, I_o, and anodic/cathodic charge transfer coefficients (α_a / α_c), were calculated. Limiting currents, I_l, were observed in all reaction conditions. The apparent reaction order, q, was found in most cases, within experimental error, close to 0.5 suggesting a possible reaction model, where a competition exists between charge transfer and mass transport of hydrogen ad-atoms or protons along the electrode/solid electrolyte interface.