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薄膜旋转圆盘电极方法是一种常用的评价气体物质在纳米电催化剂上的反应活性的方法,但是在数据分析过程中经常忽视了气体反应物在催化剂层中到活性位点的传质可能对估算的反应动力学参数的影响.本文以氧电极反应为例,使用薄膜旋转圆盘电极研究了不同担载量Pt/C电极的氧还原活性.实验结果表明,根据Koutecky-Levich方程求算相同电位下的“表观动力学电流密度”(对Pt活性面积归一化的mA/cm2Pt)或比质量电流(mA/μg Pt)随Pt担载量的减小而增大,说明在估算动力学电流时不能忽略O2在催化剂层中的扩散传质,而气体在催化剂层中的传质与催化剂层的结构、厚度、纳米催化剂的分散度等密切相关.建议在使用薄膜旋转圆盘电极方法来研究纳米催化剂气体电极反应活性时,首先系统考察担载量、分散度与催化剂层厚的影响,然后根据不同担载量催化剂归一化后的动力学电流密度(或比质量电流)-电势曲线是否重合来验证得到的是否是真实的动力学电流,从而得到更为准确的评价结果.
Thin-film rotating disk electrode method is a commonly used method to evaluate the reactivity of gaseous materials on nano-electrocatalysts. However, the mass transfer of gaseous reactants to the active sites in the catalyst layer is often neglected during the data analysis. The kinetic parameters of the reaction were estimated.In this paper, the oxygen reduction reaction was used as an example to study the oxygen reduction activity of the Pt / C electrodes with different loadings by using the thin film rotating disk electrode.The experimental results show that the calculation is the same according to the Koutecky-Levich equation The “apparent kinetic current density” (normalized mA / cm2 Pt to Pt active area) or specific mass current (mA / μg Pt) at potentials increases with decreasing Pt loading, indicating that at The diffusion kinetics of O2 in the catalyst layer can not be neglected when calculating the kinetic current, and the mass transfer of the gas in the catalyst layer is closely related to the structure, thickness of the catalyst layer, the dispersion degree of the nano-catalyst, etc. It is suggested that in the case of using the film rotating disk Electrode method to study the catalytic activity of nano-catalyst gas electrode, the first system to investigate the loading, dispersion and catalyst layer thickness, and then under different loading catalyst normalized power Current density (mass ratio or current) - potential curve obtained to verify whether the coincidence is true whether the current kinetics, resulting in a more accurate evaluation results.