An accurate evaluation for the activity of nano-sized electrocatalysts by a thin-film rotating disk electrode: Oxygen reduction on Pt/C

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• 作者：Ke Ke ^{kekeicpm@hotmail.com} ; Kazutaka Hiroshima ; Yuji Kamitaka ; Tatsuya Hatanaka ; ^{t_hatanaka@mosk.tytlabs.co.jp} ; Yu Morimoto ^{morimoto@mosk.tytlabs.co.jp}
• 关键词：Thin-film rotating disk electrode ; Oxygen reaction reduction ; Platinum ; Fuel cells ; Microcontact-coating fine-droplets
• 刊名：Electrochimica Acta
• 出版年：2012
• 期刊代码：30_00134686
• 类别：ch
• 出版时间：30 June, 2012
• 卷：72
• 期：Complete
• 页码：120-128
• 文件大小：1487 K

摘要

Up to now, it remains to be a challenge to accurately and reproducibly evaluate the oxygen reduction reaction (ORR) activity by a thin-film rotating disk electrode (TF-RDE) and results in literatures often disagree. In this work, we developed an 鈥渋ntermittently microcontact-coating fine-droplets鈥?method of preparing homogeneous thin-film to guarantee the accuracy of electro-catalytic activity evaluation by a TF-RDE, in which the measured electrode current is controlled by both the diffusion of the reactant from the electrolyte bulk to the surface of the electro-catalyst and the kinetic process on the surface of the electro-catalyst. By precisely controlling the distribution and varying the loading of nano-sized Pt/C particles on a smooth glassy carbon substrate with an in-house-developed automated electrode-preparation device, we investigated the effect of the distribution of the particles on the accuracy of compensating for diffusion limitations of ORR in an aqueous acid solution. As a reference, a smooth Pt bulk disk electrode was evaluated under the same environment to clarify the effect of the within-thin-film diffusion, which may occur in the TF-RDE. The results show that, the accuracy of correction for diffusion limitations cannot be guaranteed by only a linear relation of 1/I versus (rotation rate)^鈭?/2 in Koutecky-Levich plot and significantly depends on the distribution of the particles on the substrate. Some criteria for judging the accuracy of the compensation and optimization of the thin-film structure have been systematically discussed.