【摘要】 利用多孔电极在高频区只有双电层的充电和离子传导过程产生阻抗响应而没有法拉第过程的特点,测定了催化层中的离子电阻,研究了阳极催化层中Nafion 含量对离子电阻、甲醇氧化动力学及电池性能的影响。结果表明:利用多孔电极阻抗谱的上述特征,可以定量地考察Nafion 对催化层离子传导的影响,该法简单快捷。阳极PtRu black催化剂载量为2.0 mg/cm2,Nafion 含量为15%(质量百分数)时,电极的表观交换电流密度和甲醇氧化活性最高,阻抗弧的半径最小,电池呈现最好的放电性能,继续增加Nafion 量,电极的欧姆内阻和传质阻力增大,电极性能下降。更多还原

【Abstract】 In the present study, a new method was proposed to determine the proton transport resistance of anode catalyst layers. According to the theory of transmission-line model of gas diffusion electrode, double layer charging effects and proton transportation dominate the overall electrode response in high frequency regime, without Faradaic process. The influence of Nafion content in the anode catalyst on the methanol electro-oxidation and DMFC performance was reported. Steady-state polarization, electrochemical impedance spectroscopy (EIS) measurements of the electrodes were carried out at 75 ℃ on the single cell and half-cell model. An equivalent circuit was applied for the simulation of the measured impedance spectra. For the anode with PtRu black 2.0 mg/cm2, Nafion loading 15 %(mass percent), DMFC showed the best performance and highest activity for methanol electro-oxidation, As Nafion loading increased, the cell performance declined due to the increment in ohmic and mass transport resistances.更多还原