Electrochemical Impedance Study of Membrane−Electrode Assemblies in PEM Fuel Cells. II. Electrooxidation of H2 And H2/Co Mixtures on Pt/Ru-Based Gas-Diffusion Electrodes
Electrochemical Impedance Study of Membrane−Electrode Assemblies in PEM Fuel Cells. II. Electrooxidation of H2 And H2/Co Mixtures on Pt/Ru-Based Gas-Diffusion Electrodes
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DOI：
10.1021/jp9918407
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发表时间：
1999-10
影响因子：
3.3
通讯作者：
M. Ciureanu;H. Wang;Z. Qi
中科院分区：
文献类型：
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作者：
M. Ciureanu;H. Wang;Z. Qi
用原位电化学阻抗谱（EIS）研究了H2/CO混合气体（100 ppm和2%CO）在Pt/Ru气体扩散电极（GDE）上的电化学氧化。中毒电极的阻抗谱具有很强的浓度和电位依赖性，显示出表面活性的三种状态的证据：a）在0 - 0.3 V电位范围内的状态，其中阻抗非常高，并随偏置电位而增加;将EIS中的低频回路分配给速率确定步骤（CO吸附或扩散），而高频电弧提供了一个更快的过程的证据，即在CO吸附层中预先存在的空穴上的电荷转移;（B）在0.3 V和临界电位（Vcrit）之间的状态，其中阻抗随电位减小;该区域的典型特征是伪感应图案的出现，在最低频率下的（电感）回路，归因于Ru−OHads对Pt−COads的氧化。时间尺度…
The electrochemical oxidation of H2/CO mixtures (100 ppm and 2% CO) on Pt/Ru gas-diffusion electrodes (GDE) is examined using in-situ electrochemical impedance spectroscopy (EIS). The impedance spectrum of the poisoned electrode is strongly concentration, and potential dependent, showing evidence for three states of activity of the surface: a) a state in the 0−0.3 V potential range, in which the impedance is very high and increases with the bias potential; a low-frequency loop in EIS is assigned to the rate-determining step (CO adsorption or diffusion), while a high-frequency arc provides evidence for a more rapid processthe charge transfer on holes preexisting in the CO ads adlayer; (b) a state between 0.3 V and a critical potential (Vcrit), in which the impedance decreases with potential; the characteristic feature in this region is the appearance of a pseudo-inductive pattern, with a negative (inductive) loop at the lowest frequencies, assigned to the oxidation of Pt−COads by Ru−OHads. The time scale ...