三维膜电极电控离子分离过程离子扩散特性研究

Ion Diffusion in Three-Dimensional Film Electrodes for ECIS Process

通过阴极电沉积法在石墨芯基体上制备铁氰化镍(NiHCF)薄膜,然后组装为多排石墨芯(MRGC)膜电极系统于1mol/LKNO3溶液中测定其循环伏安(CV)曲线。重点考察了不同电极厚度与间距的MRGC基体NiHCF膜电极CV图的阴阳极峰电位分离情况,以及不同扫描速度下膜电极系统的CV图变化情况。研究结果表明,由于三维MRGC膜电极系统内部离子扩散影响,CV图的峰电位将发生偏移。随着石墨芯间距的增加电极内离子扩散阻力降低,导致CV图阴阳极峰电位差ΔEp将减小;固定石墨芯间距而增加电极厚度时电极内离子扩散阻力增加使ΔEp也随之增加;随着扫描速度的增加内扩散的影响加剧导致ΔEp增加。因此循环伏安图阴阳极峰电位的分离程度可用于三维膜电极内离子扩散的分析。

Nickel hexacyanoferrate （NiHCF） thin films were synthesized on graphite core substrates by cathodically deposition, and then were assembled as multi-row graphite core （MGRC） film electrodes. The cyclic voltammetry （CV） of the MGRC film electrodes was determined in 1 mol·L^-1 KNO3 solution. The separation （△Ep） between the anodic and cathodic peak potentials in the CV curves of MRGC film electrodes with different thickness and spacing was investigated, and the change of CV curves at different scan rates was also measured. Experimental results show that, the excursion of the peak potential of CV curves is caused by ion diffusion in three-dimensional MRGC film electrodes; the ion diffusion resistance in electrode decreases with the increase of thickness of graphite matrix, this leads to the decrease of △Ep with the increase of spacing between graphite cores. With the increase of the scan rate, AEp is also increased because of the inner diffusion in the film electrodes. Therefore, the separation degree between the anodic and cathodic peak potentials in the CV curves can be used to analyze the ion diffusion in three-dimensional film electrodes.