分析了"自呼吸式"直接甲醇燃料电池膜电极性能衰减的因素及其影响程度。通过对膜电极进行2 000 h恒电流(25 m A/cm2)放电,对比了放电前后的极化曲线、交流阻抗谱及电化学活性面积。恒电流放电后,膜电极的最大功率密度从初始的29.1 m W/cm2下降到21.8 m W/cm2,开路电压基本不变;交流阻抗谱定量分析表明,阴极的电阻明显大于阳极,并且对膜电极性能衰减的影响程度是:阴极>>阳极>质子交换膜;循环伏安测试显示阴极催化剂电化学活性面积的衰减为21%,明显大于阳极催化剂的衰减2%。
Carbon nanotubes with diameters ranging between 140～220nm was synthesized with chemical vapor deposition method, and treated using nitric acid as oxidant. Pt/C catalysts were prepared using untreated and treated carbon nanotubes as supports, respectively. TEM and FT IR differential spectra showed that treated carbon nanotubes become short and possess more oxygen containing surface groups. The electrochemical studies indicated that the Pt/treated carbon nanotubes catalyst possessed much higher electrocatalytic activity for the oxidation of methanol than that of the Pt/untreated carbon nanotubes catalyst.
