质子交换膜燃料电池催化层电流形成途径的单电池研究

Study of Current Generation Mechanism in PEMFC Catalyst Layer

利用特殊设计的三电极单电池测量系统，研究了具有“双层结构催化层”中电流的形成途径和动力学。“双层结构催化层”通过在正常的“Pt／C＋Nafion”催化层与扩散层碳纸之间引入一薄层Pt黑或Pt／C形成。循环伏安测量表明，尽管外加催化层中不舍电解质组分，但其中的催化剂仍然可以参与电流的形成，并且外加层中的催化剂的利用率与气体湿度密切相关。初步的研究结果表明，未与Nation膜直接接触的催化剂主要通过反应物的吸附以及吸附物种表面扩散过程参与燃料电池反应。

By introducing a layer of Pt （or Pt/C） between the normal ＂Pt/C＋ Nafion＂ catalyst layer and the gas diffusion layer, a PEMFC single ceil with dual catalyst layer is established. Although the additional catalyst layer doesn＇ t contain electrolyte, the current produced by the PEMFC with dual catalyst layer is much larger than that when the additional catalyst layer is absent, indicating that the catalyst not contacting with the electrolyte can participate the current formation. It is also shown that the humidity of the feeding gas have crucial impacts on the utilization of catalyst in the additional catalyst layer.