DMFC阳极催化剂的失活特性

Characteristics of the Activity Loss of Anode Catalyst in DMFC

采用电化学老化试验考察直接甲醇燃料电池(DMFC)阳极PtRu/C催化剂的失活过程。结果表明,老化试验后PtRu/C催化剂的甲醇氧化活性明显降低。透射电镜和X射线衍射分析结果表明,在老化试验中催化剂粒子经历了Otswald熟化过程和电场作用下的微晶定向迁移过程。电化学阻抗谱分析表明,老化试验后催化层的欧姆电阻和极化阻抗都显著增加,这与活性组分的流失有关。X射线能谱分析显示,老化试验后催化剂的Pt:Ru质量比显著升高。由电位波动引起的活性组分流失是导致DMFC阳极催化剂失活的重要原因。

The activity loss of anode PtRu/C catalyst in direct methanol fuel cell （DMFC） was examined by an electrochemical aging test. The results show that after the aging test, the activity of PtRu/C catalyst toward methanol oxidation decreased obviously. The transmission electron microscopy and X-ray diffraction analysis display that catalyst particles experienced Otswald ripening and directional migration under the electric field during the aging test. The electrochemical impedance spectra show that after the aging test, both the ohmic resistance and the polarization impedance increased remarkably, which is related to the loss of active components. The energy dispersive X-ray analysis shows that the mass ratio of Pt to Ru in the catalyst layer increased noticeably after the test. It is suggested that the loss of active components due to the potential fluctuation is an important factor responsible for the activity loss of the anode catalyst in DMFC.