Local Structure, Electronic Behavior, and Electrocatalytic Reactivity of CO-Reduced Platinum鈥揑ron Oxide Nanoparticles
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- 作者：Paul N. Duchesne ; Guangxu Chen ; Nanfeng Zheng ; Peng Zhang
- 刊名：Journal of Physical Chemistry C
- 出版年：2013
- 出版时间：December 12, 2013
- 年：2013
- 卷：117
- 期：49
- 页码：26324-26333
- 全文大小：515K
- 年卷期：v.117,no.49(December 12, 2013)
- ISSN：1932-7455
文摘
A series of platinum鈥搃ron oxide nanoparticles was synthesized using a 鈥渃lean鈥?CO-reduction method that employed different ratios of Pt鈭扚e precursor salts in oleylamine at elevated temperatures. High-resolution transmission electron microscopy (HRTEM) and energy-dispersive X-ray spectroscopy (EDS) studies revealed that nearly monodisperse (i.e., with relative standard deviations of less than 15%) nanoparticles with mean diameters of 3.5鈥?.4 nm and varied elemental compositions (Pt54Fe46 Pt70Fe30, and Pt87Fe13) were obtained. X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) measurements at the Pt L3- and Fe K-edges revealed that these nanoparticles all consisted of a Pt core with amorphous iron oxide on the surface. Furthermore, it was observed that the local structure (e.g., Pt鈥揚t bond distance and coordination number) and electronic behavior of the Pt鈥揊eO nanoparticles (e.g., Pt d electron density and Fe valence state) are dependent on the Pt鈭扚e precursor ratios used in their synthesis. Quantum mechanical ab initio calculations were employed to interpret the results from X-ray spectroscopy and help elucidate the relationships between local structure and electronic properties in the nanoparticle samples. Finally, the surface reactivity of these nanoparticles in the oxygen reduction reaction (ORR) was explored, demonstrating higher electrocatalytic activity for all three platinum鈥搃ron oxide samples in comparison with a commercial Pt catalyst. The surface reactivity was also found to be sensitive to the Pt鈭扚e ratios of the nanoparticles and could be correlated with their local structure and electronic behavior.