Laboratoire des Matériaux, Surfaces et Procédés pour la Catalyse, UMR 7515 du CNRS-UdS, Ecole de Chimie, Polymères et Matériaux, Université de Strasbourg, Strasbourg, France.
Langmuir. 2011 Jul 19;27(14):9018-27. doi: 10.1021/la2006343. Epub 2011 Jun 14.
Insufficient understanding of the mechanism of the cathodic oxygen reduction reaction puts constraints on the improvement of the efficiency of polymer electrolyte fuel cells (PEMFCs). We apply ordered catalytic layers based on vertically aligned carbon nanofilaments and combine experimental rotating ring-disk studies with mathematical modeling for shedding light on the mechanism of the oxygen reduction reaction on Pt nanoparticles. Based on the experimental and simulation evidence we propose a dual path ORR mechanism which comprises a "direct 4e(-)" and a "series 2e(-) + 2e(-)" pathway and explains switching between the two. For the first time we show that below 0.8 V the "direct" path may be discarded and the ORR predominantly occurs via H(2)O(2) mediated pathway, while in the potential interval between ca. 0.8 V and the onset of the ORR the "direct" path is dominating.
对阴极氧还原反应机制的认识不足，限制了聚合物电解质燃料电池（PEMFCs）效率的提高。我们应用基于垂直排列碳纳米纤维的有序催化层，并结合实验旋转环盘研究和数学建模，阐明了 Pt 纳米颗粒上氧还原反应的机制。基于实验和模拟证据，我们提出了一种双路径 ORR 机制，包括“直接 4e(-)”和“串联 2e(-) + 2e(-)”途径，并解释了两者之间的转换。我们首次表明，在 0.8 V 以下，“直接”途径可能被忽略，ORR 主要通过 H(2)O(2)介导的途径发生，而在约 0.8 V 到 ORR 起始之间的电位区间内，“直接”途径占主导地位。
