Direct observation of the oxygenated species during oxygen reduction on a platinum fuel cell cathode
Direct observation of the oxygenated species during oxygen reduction on a platinum fuel cell cathode
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DOI：
10.1038/ncomms3817
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发表时间：
2013-12-01
影响因子：
16.6
通讯作者：
Ogasawara, Hirohito
中科院分区：
文献类型：
--
作者：
Casalongue, Hernan Sanchez;Kaya, Sarp;Ogasawara, Hirohito
聚合物电解质膜燃料电池的性能受到氧还原反应的四电子途径中的各种含氧中间体在阴极处的还原的限制。在这里，我们使用环境压力X射线光电子能谱，并直接探测表面上的吸附物种和电化学电位之间的相关性。我们证明，在氧还原反应过程中，在阴极表面上的羟基中间体发生在几种配置具有显着不同的结构和反应性。特别是，我们发现，接近开路电位，非水合羟基是占主导地位的表面物种。基于密度泛函理论计算，我们发现，水化的去除增强了氧物种的反应性。调节三相边界附近的羟基水合作用对于设计更活跃的燃料电池阴极至关重要。
The performance of polymer electrolyte membrane fuel cells is limited by the reduction at the cathode of various oxygenated intermediates in the four-electron pathway of the oxygen reduction reaction. Here we use ambient pressure X-ray photoelectron spectroscopy, and directly probe the correlation between the adsorbed species on the surface and the electrochemical potential. We demonstrate that, during the oxygen reduction reaction, hydroxyl intermediates on the cathode surface occur in several configurations with significantly different structures and reactivities. In particular, we find that near the open-circuit potential, non-hydrated hydroxyl is the dominant surface species. On the basis of density functional theory calculations, we show that the removal of hydration enhances the reactivity of oxygen species. Tuning the hydration of hydroxyl near the triple phase boundary will be crucial for designing more active fuel cell cathodes.