Pd/Mm(富铈稀土)薄膜电极在KOH溶液中的电化学行为

利用磁控溅射法制备了Pd/Mm(Mischmetal)混合稀土薄膜,采用X射线衍射、AFM及循环伏安和交流阻抗谱等电化学测试技术研究了Pd/Mm稀土薄膜的晶体结构、表面形貌及其在KOH溶液中的电化学行为.结果表明,Pd/Mm薄膜表面的Pd层由纳米级的孤岛状颗粒构成,颗粒大小为100～200 nm.循环伏安法研究表明,氢的电化学氧化和还原均通过表面Pd金属层进行.Pd/Mm稀土薄膜电极的交流阻抗图由两个容抗弧组成,低频区的容抗弧对应氢在电极中的固态扩散过程,而高频段的容抗弧对应氢在电极表面的电化学还原过程,其中氢在薄膜电极内部的扩散是速率控制步骤.

Electrochemical Behaviors of Pd/Mm Rare Earth Film Electrodes in KOH Solution

Pd/Mm(mischmetal) rare earth films were prepared by magnetron sputtering technology,the crystal structure,morphology and electrochemical behavior of the as prepared films were investigated by using XRD,AFM and electrochemical measurement techniques including cyclic voltammetry and AC impedance.The results showed that Pd coatings is a kind of island structure with 30～50 nm in size.The electrochemical reduction or oxidation of hydrogen only occurred on the Pd coatings.The electrochemical impedance spectra of Pd/Mm film electrodes was composed of two semi circles,of which the low frequency zone is corresponded to the solid diffusion process of H atom in the film,and the high one to the electrochemical reaction on the surface of the electrode.The solid diffusion process of H atom in the inner rare earth layer is the rate controlled step.