过电位
限制电流
扩散电流
传质
电流密度
扩散
化学
电流(流体)
电极
旋转圆盘电极
交换电流密度
限制
动能
热力学
分析化学(期刊)
电化学
物理化学
物理
经典力学
色谱法
塔菲尔方程
工程类
机械工程
量子力学
循环伏安法
作者
Mian-Le Xu,Wei Chen,Lingwen Liao,Zhen Wei,Jun Cai,Yanxia Chen
标识
DOI:10.1063/1674-0068/cjcp2006085
摘要
Rotating disk electrode systems are widely used to study the kinetics of electrocatalytic reactions that may suffer from insufficient mass transfer of the reactants. Kinetic current density at certain overpotential calculated by the Koutecky-Levich equation is commonly used as the metrics to evaluate the activity of electrocatalysts. However, it is frequently found that the diffusion limiting current density is not correctly identified in the literatures. Instead of kinetic current density, the measured current density normalized by diffusion limiting current density (j/jL) has also been frequently under circumstance where its validity is not justified. By taking oxygen reduction reaction/hydrogen oxidation reaction/hydrogen evolution reaction as examples, we demonstrate that identifying the actual diffusion limiting current density for the same reaction under otherwise identical conditions from the experimental data is essential to accurately deduce kinetic current density. Our analysis reveals that j/jL is a rough activity metric which can only be used to qualitatively compare the activity trend under conditions that the mass transfer conditions and the roughness factor of the electrode are exactly the same. In addition, if one wants to use j/jL to compare the intrinsic activity, the concentration overpotential should be eliminated.
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