Restructuring of Palladium Nanoparticles during Oxidation by Molecular Oxygen
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Date
2024-10-17
Publication Type
Journal Article
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Abstract
An interplay between Pd and PdO and their spatial distribution inside the particles are relevant for numerous catalytic reactions. Using in situ time-resolved X-ray absorption spectroscopy (XAS) supported by theoretical simulations, a mechanistic picture of the structural evolution of 2.3 nm palladium nanoparticles upon their exposure to molecular oxygen is provided. XAS analysis revealed the restructuring of the fcc-like palladium surface into the 4-coordinated structure of palladium oxide upon absorption of oxygen from the gas phase and formation of core@shell Pd@PdO structures. The reconstruction starts from the low-coordinated sites at the edges of palladium nanoparticles. Formation of the PdO shell does not affect the average Pd-Pd coordination numbers, since the decrease of the size of the metallic core is compensated by a more spherical shape of the oxidized nanoparticles due to a weaker interaction with the support. The metallic core is preserved below 200 degrees C even after continuous exposure to oxygen, with its size decreasing insignificantly upon increasing the temperature, while above 200 degrees C, bulk oxidation proceeds. The Pd-Pd distances in the metallic phase progressively decrease upon increasing the fraction of the Pd oxide due to the alignment of the cell parameters of the two phases.
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published
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Journal / series
Volume
20 (42)
Pages / Article No.
2401184
Publisher
Wiley-VCH
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Subject
core-shell; EXAFS; palladium oxide; XANES
Organisational unit
03746 - Van Bokhoven, Jeroen A. / Van Bokhoven, Jeroen A.