Probing the Formation and Evolution of Pd Nanoparticles on the Surface of γ-Al2O3 using a Pd(II) Coordinating Polymer as a Precursor: An in-situ X-ray Scattering and Spectroscopy Study
Date
2024-06-26
Authors
Singh, Siddhant
Scott, Robert W.J.
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American Chemical Society
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Abstract
Due to the small size and very low metal loadings in heterogeneously supported nanoparticle catalysts, it is a characterization challenge to trace and control the formation and structural evolution of nanoparticles during their synthesis. In this report, we have probed the formation of alumina-supported Pd nanoparticles by thermal treatment of a 1:3 composite of a Pd(II) coordination polymer (Pd(II)-CP) and a γ-Al2O3 powder using in situ X-ray total scattering and X-ray absorption spectroscopy. By comparing the pyrolysis process of Pd(II)-CP in the absence and presence of γ-Al2O3, we found that the sintering of Pd nanoparticles by the coalescence of nucleation sites can be significantly reduced on γ-Al2O3 surfaces. The introduction of γ-Al2O3 provides far better control over the size, distribution, and speciation of the synthesized Pd nanoparticles. The results showed that the sintering of Pd nanoparticles does not occur on the surface of γ-Al2O3 until the Pd(II)-CP structure is fully collapsed at 400 °C, most likely because the organic framework of Pd(II)-CP provides spatially distinct sites for Pd nucleation. Moreover, the interface of the γ-Al2O3 surface and Pd(II)-CP protected the Pd nanoparticle nucleation sites from air oxidation up to 500 °C. Thereafter, a slow conversion of the Pd fcc phase to the PdO phase started taking place, which was facilitated by the formation of an amorphous PdOx phase as an intermediate.
Description
This document is the Accepted Manuscript version of a Published Work that appeared in final form in The Journal of Physical Chemistry C, copyright © 2024 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/10.1021/acs.jpcc.4c03277.
DOI: 10.1021/acs.jpcc.4c03277
Keywords
Diffraction, Extended X-ray absorption fine structure, Metal nanoparticles, Nucleation, Palladium
Citation
Siddhant Singh and Robert W. J. Scott (2024) Probing the Formation and Evolution of Pd Nanoparticles on the Surface of γ-Al2O3 Using a Pd(II) Coordination Polymer as a Precursor: An In Situ X-ray Scattering and Spectroscopy Study. The Journal of Physical Chemistry C 2024 128 (27), 11427-11436 DOI: 10.1021/acs.jpcc.4c03277
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DOI
10.1021/acs.jpcc.4c03277