Effect of Electrode Pt Loading on the Oxygen Reduction Reaction Evaluated by Rotating Disk Electrode and Its Implication on the Reaction Kinetics

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• 作者：Yu-Hung Shih ; Guggilla Vidya Sagar ; Shawn D. Lin
• 刊名：Journal of Physical Chemistry C
• 出版年：2008
• 出版时间：January 10, 2008
• 年：2008
• 卷：112
• 期：1
• 页码：123 - 130
• 全文大小：416K
• 年卷期：v.112,no.1(January 10, 2008)
• ISSN：1932-7455

文摘

The oxygen reduction reaction (ORR) activity was evaluated over film electrodes prepared from different Ptcatalysts using rotating-disk electrode (RDE) and rotating-ring-disk electrode (RRDE) systems. The ORRactivity as a function of Pt loading using the same catalyst was examined first, and it is concluded to bestrongly influenced by mass transfer limitation. Two types of mass transfer limitation were identified. One isthe external diffusion as described by the rotating-speed-dependent Levich equation. The other one is theinternal diffusion within the electrode in which the electrode thickness is the governing parameter. The electrodethickness is closely related to the catalyst loading of the electrodes. After corrections of these mass transferlimitations, all the tested Pt catalysts under the conditions of this study show similar specific ORR activitywith a Tafel slope near -120 mV/dec This result suggests that the ORR over Pt catalysts is a structure-insensitive reaction and the overall electrode performance can be limited by the mass transfer.