Synthesis of Pd鈭扨t Bimetallic Nanocrystals with a Concave Structure through a Bromide-Induced Galvanic Replacement Reaction

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• 作者：Hui Zhang ; Mingshang Jin ; Jinguo Wang ; Weiyang Li ; Pedro H. C. Camargo ; Moon J. Kim ; Deren Yang ; Zhaoxiong Xie ; Younan Xia
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：April 20, 2011
• 年：2011
• 卷：133
• 期：15
• 页码：6078-6089
• 全文大小：1691K
• 年卷期：v.133,no.15(April 20, 2011)
• ISSN：1520-5126

文摘

This article describes a systematic study of the galvanic replacement reaction between PtCl₆^{2鈭?/sup> ions and Pd nanocrystals with different shapes, including cubes, cuboctahedrons, and octahedrons. It was found that Br鈭?/sup> ions played an important role in initiating, facilitating, and directing the replacement reaction. The presence of Br鈭?/sup> ions led to the selective initiation of galvanic replacement from the {100} facets of Pd nanocrystals, likely due to the preferential adsorption of Br鈭?/sup> ions on this crystallographic plane. The site-selective galvanic replacement resulted in the formation of Pd鈭扨t bimetallic nanocrystals with a concave structure owing to simultaneous dissolution of Pd atoms from the {100} facets and deposition of the resultant Pt atoms on the {111} facets. The Pd鈭扨t concave nanocubes with different weight percentages of Pt at 3.4, 10.4, 19.9, and 34.4 were also evaluated as electrocatalysts for the oxygen reduction reaction (ORR). Significantly, the sample with a 3.4 wt.% of Pt exhibited the largest specific electrochemical surface area and was found to be four times as active as the commercial Pt/C catalyst for the ORR in terms of equivalent Pt mass.}