金属离子对SPE膜电极组件电导率的影响

Research on the conductivity characteristics of SPE membrane-electrode assembly contaminated by metal ions

本文使用交流阻抗法测定受Fe3+,Mg2+,Ca2+污染后的膜组件电导率变化情况,对比研究了两侧化学镀铂Nafion膜对这3种离子的抗干扰能力。研究发现,受Mg2+污染后的膜组件电导率下降最大,Fe3+,Ca2+次之。研究认为:Fe3+,Ca2+的影响主要由于这2种离子在Nafion膜内的低电迁移率所致,膜内阻塞效应较强;Mg2+较Fe3+,Ca2+在膜内的电迁移率较大,膜内阻塞效应只少部分降低膜组件电导率大小,更大影响来自于污染电解过程中膜与镀铂层间氧化物的形成。结果表明,各离子与Nafion的亲和力顺序为:Mg2+<Ca2+≈Fe3+。

The conductivity of membrane-electrode assembly contaminated by Fe3＋ , Mg2＋ , Ca2＋ were measured using ac impedance method. The anti-jamming ability of ＂Pt/Nafion membrane/Pt＂ MEA to these impurity ions were compared. In our experiments we discovered that the Mg2＋ caused larger conductivity decrease than Ca2＋ , Fe3＋. The reason that the conductivity decreased seriously for Fe3＋ , Ca2＋ ion contamination mainly come from the strong blocking effects due to the low electric transference ability of these two ions inside the Nafion membrane;while for Mg2＋ , the blocking effect is only one of the reasons, another important factor may be some new materials formation between the Pt catalyst and Nafion membrane. The results show the affinity order of these three ions to membrane is： Mg2＋ 〈 Ca2＋ ≈ Fe3＋.