Department of Engineering, Graduate School of Integrated Science and Technology , Shizuoka University , Shizuoka 432-8561 , Japan.
Department of Environmental Engineering and Green Technology, Malaysia-Japan International Institute of Technology , University Technology Malaysia , 54100 Kuala Lumpur , Malaysia.
Anal Chem. 2018 May 15;90(10):6116-6123. doi: 10.1021/acs.analchem.8b00247. Epub 2018 May 2.
Organically (octyl amine, OA) surface modified electrocatalyst (OA-Pt/CB) was studied for its oxygen reduction reaction (ORR) activity via dc methods and its charge and mass transfer properties were studied via electrochemical impedance spectroscopy (EIS). Comparison with a commercial catalyst (TEC10V30E) with similar Pt content was also carried out. In EIS, both the catalysts showed a single time-constant with an emerging high-frequency semicircle of very small diameter which was fitted using suitable equivalent circuits. The organically modified catalyst showed lower charge-transfer resistance and hence, low polarization resistance in high potential region as compared to the commercial catalyst. The dominance of kinetic processes was observed at 0.925-1.000 V, whereas domination of diffusion based processes was observed at lower potential region for the organic catalyst. No effect due to the presence of carbon was observed in the EIS spectra. Using the hydrodynamic method, higher current penetration depth was obtained for the organically modified catalyst at 1600 rpm. Exchange current density and Tafel slopes for both the electrocatalysts were calculated from the polarization resistance obtained from EIS which was in correlation with the results obtained from dc methods.
通过直流方法研究了有机（辛胺，OA）表面修饰电催化剂（OA-Pt/CB）对氧还原反应（ORR）的活性，并通过电化学阻抗谱（EIS）研究了其电荷和质量转移特性。还对具有相似 Pt 含量的商业催化剂（TEC10V30E）进行了比较。在 EIS 中，两个催化剂都显示出单一的时间常数，出现了非常小直径的高频半圆，使用合适的等效电路对其进行了拟合。与商业催化剂相比，有机修饰的催化剂在高电位区域表现出较低的电荷转移电阻，因此极化电阻较低。在 0.925-1.000 V 时观察到动力学过程的主导地位，而在较低的电位区域观察到扩散过程主导地位的有机催化剂。在 EIS 谱中没有观察到由于碳的存在而产生的影响。使用动电方法，在 1600 rpm 时，有机修饰的催化剂获得了更高的电流穿透深度。从 EIS 获得的极化电阻计算了两个电催化剂的交换电流密度和塔菲尔斜率，这与直流方法的结果相关。
