Effect of Reaction Atmosphere on the Electrocatalytic Activities of Pt/C and PtRu/C Obtained in a Polyol Process

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• 作者：Huanqiao Li ; Gongquan Sun ; Yan Gao ; Qian Jiang ; Ziqi Jia ; Qin Xin
• 刊名：Journal of Physical Chemistry C
• 出版年：2007
• 出版时间：October 25, 2007
• 年：2007
• 卷：111
• 期：42
• 页码：15192 - 15200
• 全文大小：489K
• 年卷期：v.111,no.42(October 25, 2007)
• ISSN：1932-7455

文摘

Pt and PtRu nanoparticles supported on Vulcan XC-72R carbon obtained under different atmospheres (airand N₂) were prepared via a polyol process in ethylene glycol solution and denoted as Pt/C-N₂, Pt/C-air,PtRu/C-N₂, and PtRu/C-air, respectively. The catalysts were characterized by XRD (X-ray diffraction),TEM (transmission electron microscopy), and XPS (X-ray photoelectron spectroscopy). TEM images showthat metal nanoparticles are uniform in size and are well dispersed on the carbon support for all the catalysts.The mean particle sizes of Pt/C-N₂, Pt/C-air, PtRu/N₂, and PtRu/C-air are 2.6, 2.7, 2.3, and 1.8 nm,respectively. Among these samples, PtRu/C-air catalyst has the smallest nanoparticle size with a narrowsize distribution. The three strongest diffraction peaks of both Pt/C-N₂ and Pt/C-air catalysts are located at2 = 39, 46, and 67, corresponding to the Miller indices of (111), (200), and (220) of a Pt fcc (face-centered cubic) crystal structure. The XRD pattern of PtRu/C-N₂ displays an fcc structure similar to that ofPt but different from that of PtRu/C-air. XPS analyses indicate that the amount of metallic Pt(0) and Ru(0)species present in Pt/C-N₂ and PtRu/C-N₂ catalysts are higher than those obtained in air atmosphere.Electrochemical voltammetry methods and single cell tests were employed to evaluate the activities of thesecatalysts. The results show that Pt/C-N₂ and PtRu/C-N₂ catalysts exhibit much better activities for oxygenreduction and methanol oxidation reactions in direct methanol fuel cells than the corresponding Pt/C-air andPtRu/C-air catalysts.