Characterization of Hydrous Palladium Oxide: Implications for Low-Temperature Carbon Monoxide Oxidation

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• 作者：Stewart F. Parker ; Keith Refson ; Alex C. Hannon ; Emma R. Barney ; Stephen J. Robertson ; Peter Albers
• 刊名：Journal of Physical Chemistry C
• 出版年：2010
• 出版时间：August 26, 2010
• 年：2010
• 卷：114
• 期：33
• 页码：14164-14172
• 全文大小：495K
• 年卷期：v.114,no.33(August 26, 2010)
• ISSN：1932-7455

文摘

The structure of hydrous palladium oxide has been investigated by powder diffraction with both X-rays and neutrons, transmission electron microscopy, inelastic neutron scattering spectroscopy, infrared spectroscopy, and periodic-DFT calculations. The results clearly show the formulation as PdO·H₂O is correct rather than as Pd(OH)₂ as has been proposed previously. The material is best described as 18 Å diameter particles of nanocrystalline PdO with a monolayer or so of hydroxyls capped by 4−7 layers of water. The very small nanocrystallites are agglomerated into larger clusters which reduces the effective surface area. This structure is very similar to that proposed for hydrous ruthenium oxide, RuO₂·xH₂O, x = 2, and for water on anatase and rutile. This model provides a quantitative explanation for why hydrous palladium oxide deactivates three times faster at 25 °C than at 100 °C in the low-temperature oxidation of CO to CO₂.