Effect of the structure of Pt-Ru/C particles on COad monolayer vibrational properties and electrooxidation kinetics
Effect of the structure of Pt-Ru/C particles on COad monolayer vibrational properties and electrooxidation kinetics
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DOI：
10.1016/j.electacta.2007.07.061
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发表时间：
2007-12
影响因子：
6.6
通讯作者：
F. Maillard;A. Bonnefont;M. Chatenet;L. Guetaz;B. Doisneau-cottignies;H. Roussel;U. Stimming
中科院分区：
文献类型：
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作者：
F. Maillard;A. Bonnefont;M. Chatenet;L. Guetaz;B. Doisneau-cottignies;H. Roussel;U. Stimming
在本文中，我们结合 FTIR 光谱和 COadstripping 伏安法研究 Pt-Ru/C 纳米颗粒上的 COad 吸附和电氧化。 Pt:Ru 元素组成和金属负载量通过 ICP-AES 测定。 Pt-Ru/C 的 X 射线衍射图表明形成了 Pt-Ru (fcc) 合金。 HREM 图像显示，随着金属负载量的增加，团聚的 Pt-Ru/C 颗粒的比例增加，并表明团聚的 Pt-Ru/C 纳米颗粒存在结构缺陷，例如孪晶或晶界。此外，无论金属负载量如何，分离的 Pt-Ru/C 纳米颗粒都具有相似的平均粒径（约 2.5 nm）和粒径分布。因此，我们可以精确确定颗粒团聚对 CO 振动特性和电氧化动力学的影响。 FTIR 测量揭示了一个主要的 COad 拉伸带位于大约。 [分子式：见正文]，我们将其归因于通过 Ru 的存在进行电子修饰的 a-top COadon Pt 结构域。随着金属负载量的增加，该带的位置蓝移约。 5cm−1 和约 2005cm−1 的肩部发育，这归因于 a 顶 COadon Ru 结构域。其原因被认为是团聚的 Pt-Ru/C 颗粒上 Ru 域尺寸的增加，这增强了偶极-偶极耦合并允许观察到两种振动特征（COad/Ru、COad/Pt）。这证明 FTIR 光谱可用于探测 Pt-Ru/C 表面的微小化学波动。最后，我们对 COad 电氧化动力学进行了评论。我们观察到，随着金属负载量（即团聚的 Pt-Ru/C 纳米粒子的分数）的增加，COad 更容易转化为 CO2。
In this paper, we combined FTIR spectroscopy and COadstripping voltammetry to investigate COadadsorption and electrooxidation on Pt–Ru/C nanoparticles. The Pt:Ru elemental composition and the metal loading were determined by ICP-AES. The X-ray diffraction patterns of the Pt–Ru/C indicated formation of a Pt–Ru (fcc) alloy. HREM images revealed an increase in the fraction of agglomerated Pt–Ru/C particles with increasing the metal loading and showed that agglomerated Pt–Ru/C nanoparticles present structural defects such as twins or grain boundaries. In addition, isolated Pt–Ru/C nanoparticles have similar mean particle size (ca. 2.5nm) and particle size distributions whatever the metal loading. Therefore, we could determine precisely the effect of particle agglomeration on the COadvibrational properties and electrooxidation kinetics. FTIR measurements revealed a main COadstretching band at ca. [Formula: see text] , which we ascribed to a-top COadon Pt domains electronically modified by the presence of Ru. As the metal loading increased, the position of this band was blue shifted by ca. 5cm−1and a shoulder around 2005cm−1developed, which was ascribed to a-top COadon Ru domains. The reason for this was suggested to be the increasing size of Ru domains on agglomerated Pt–Ru/C particles, which lifts dipole–dipole coupling and allows two vibrational features to be observed (COad/Ru, COad/Pt). This is evidence that FTIR spectroscopy can be used to probe small chemical fluctuations of the Pt–Ru/C surface. Finally, we comment on the COadelectrooxidation kinetics. We observed that COadwas converted more easily into CO2as the metal loading, i.e. the fraction of agglomerated Pt–Ru/C nanoparticles, increased.