In Situ X-ray Absorption Spectroscopic Study of Fe@FexOy/Pd and Fe@FexOy/Cu Nanoparticle Catalysts Prepared by Galvanic Exchange

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• 作者：Yali Yao ; Christian Patzig ; Yongfeng Hu ; Robert W. J. Scott
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：September 10, 2015
• 年：2015
• 卷：119
• 期：36
• 页码：21209-21218
• 全文大小：680K
• ISSN：1932-7455

文摘

Fe@Fe_xO_y core鈥搒hell nanoparticles have been previously shown to be a versatile support for catalytic metals such as Pd and Cu. However, the resulting structure, metal speciation, and performance of such catalysts in catalytic reactions are still poorly understood. Herein, we synthesize Fe@Fe_xO_y-supported Pd and Cu nanoparticles by controlling the molar ratios of Fe@Fe_xO_y nanoparticles to Pd²⁺ or Cu²⁺ species. Scanning transmission electron microscopy analyses show that Pd or Cu NPs are deposited on the exterior shell of the Fe@Fe_xO_y nanoparticles. In situ X-ray absorption near-edge structure (XANES) spectra were used to follow the formation processes of Fe@Fe_xO_y/Pd and Fe@Fe_xO_y/Cu nanoparticles and the performance of Fe@Fe_xO_y/Pd nanoparticles for Suzuki鈥揗iyaura cross-coupling reactions. The results show that different molar ratios of Fe@Fe_xO_y nanoparticles to Pd²⁺ or Cu²⁺ lead to different morphologies of the resulting supported-NP structures. In situ XANES results show that Fe@Fe_xO_y nanoparticles can effectively fully reduce Pd or Cu salts over the course of 鈭?0 min to give small Pd or larger Cu nanoparticles on the surface and can also rereduce oxidized Pd in Suzuki鈥揗iyaura cross-coupling reactions.