Quantitative Analysis of the Coverage Density of Br鈥?/sup> Ions on Pd{100} Facets and Its Role in Controlling the Shape of Pd Nanocrystals

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• 作者：Hsin-Chieh Peng ; Shuifen Xie ; Jinho Park ; Xiaohu Xia ; Younan Xia
• 刊名：The Journal of the American Chemical Society
• 出版年：2013
• 出版时间：March 13, 2013
• 年：2013
• 卷：135
• 期：10
• 页码：3780-3783
• 全文大小：253K
• 年卷期：v.135,no.10(March 13, 2013)
• ISSN：1520-5126

文摘

We report an approach based on a combination of inductively coupled plasma mass spectrometry and X-ray photoelectron spectroscopy for quantitative analysis of the role played by Br^{鈥?/sup> ions in the synthesis of Pd nanocrystals. The Br鈥?/sup> ions were found to adsorb onto Pd{100} facets selectively with a coverage density of ca. 0.8 ion per surface Pd atom. The chemisorbed Br鈥?/sup> ions could be removed via desorption at an elevated temperature under reductive conditions. They could also be gradually released from the surface when Pd cubic seeds grew into cuboctahedrons and then octahedrons. On the basis of the coverage density information, we were able to estimate the minimum concentration of Br鈥?/sup> ions needed for the formation of Pd nanocubes with a specific size. If the concentration of Br鈥?/sup> ions was below this minimum value, not all of the {100} facets could be stabilized by the capping agent, leading to the formation of nanocubes with truncated corners. The quantitative analysis developed in this study is potentially extendable to other systems involving chemisorbed capping agents.}