Reversible Sulfidation of Pt0.3Pd0.7 Nanoparticles Investigated by in Situ Time-Resolved XAS

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• 作者：Jocenir Boita ; Fabiano Bernardi ; Marcus Vin铆cius Castegnaro ; Lucas Nicolao ; Maria C. M. Alves ; Jonder Morais
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：March 13, 2014
• 年：2014
• 卷：118
• 期：10
• 页码：5538-5544
• 全文大小：496K
• 年卷期：v.118,no.10(March 13, 2014)
• ISSN：1932-7455

文摘

In the present study, in situ X-ray absorption spectroscopy (XAS) was used to monitor the structural evolution of isolated Pt_0.3Pd_0.7 nanoparticles (NPs) subjected to different gaseous atmospheres. Time-resolved XAS measurements were performed at the Pt L₃ edge in the dispersive mode, during which X-ray absorption near edge spectra were sequentially collected. The NPs were initially activated under a reducing atmosphere at 300 掳C (H₂ + He) and subsequently exposed to a sulfidation process at the same temperature (H₂ + He + H₂S at 300 掳C). Then, the sulfided NPs were thermally treated under a reducing atmosphere, and the reversibility of the sulfidation process was successfully accomplished, for the first time in these unsupported and well-characterized nanoscale systems. The atomic local order in the vicinity of the Pt atoms was investigated by extended X-ray absorption fine structure spectroscopy throughout all of these thermal treatments, monitoring the chemical stability of the metal鈥搒ulfur bonds and allowing kinetic modeling, from which the activation energies for the sulfidation process were estimated.