浸渍-还原法制备SPE膜-电极组件的机理分析

Mechanism analysis on SPE membrane-electrode assembly prepared by impregnation-reduction method

为了研究浸渍-还原法对制备SPE膜-电极组件的影响,对浸渍-还原法的2个过程进行了深入的机理分析,通过方程计算出液膜厚度和[Pt(NH3)4]2+离子在液膜内的扩散系数,并得出以下结论:浸渍过程应为液膜扩散,使[Pt(NH3)4]2+在膜内的分布为直线,有利于还原过程中控制晶核生长速度,从而获得微细的铂颗粒;为了在膜的内表层形成精细的铂颗粒,要求离子膜内扩散是还原过程的控制步骤,同时还要求有快速的界面化学反应及较高的还原剂浓度。

In order to research the effect of impregnation-reduction method on SPE membrane-electrode assembly,the mechanism of impregnation-reduction process were analysed,the liquid film thickness and the diffusion coefficients of the[Pt（NH3）4]^2＋ in the liquid film were calculated by equation.Following points of view were proposed：the impregnation process should be controlled by liquid film,and the diffusion of[Pt（NH3）4]^2＋ in membrane should be a beeline,this were favorable to controlling the growing rate of Pt crystal in the reduction step and forming fine particles; the diffusion of ions in the Nation membrane during reduction process should be rate determining step, the fast chemic reaction on the interface and higher reductant concentration were required, which was favorable to the deposition of Pt with fine particles within the membrane but near the surface.