weak scattering from second-nearest neighbors for single atom catalysts
Hi everyone, I would like to have a discussion about the common EXAFS for single atom catalysts. It is usually observed that there is only one strong peak around 1.5A in EXAFS, and it is attributed to the nearest neighbors of O or N. Take an example of Pt1/CeO2 catalyst. Pt single atom is coordinated with a few oxygens, i.e., PtOx. These oxygens constitute the first shell of Pt. It is supposed that these O should also attach to the metal element of the support (Ce here). So there is also Pt-O-Ce structure. Why it doesnot have strong scattering peak in EXAFS? Is it that because the Pt-O-Ce formed is not ordered, or it is actually not a bond just some weak contact? Thank you very much. Qiang
Hi Qiang,
There are many papers analyzing Pt SACs on ceria and many of them are able
to provide good evidence of Pt-O-Ce coordination. See for example Fig. 5d
in this paper and the discussion of the model and fit results.
M. Kottwitz, Y. Li, R. M. Palomino, Z. Liu, Q. Wu, G. Wang, J. Huang, J.
Timoshenko, S. D. Senanayake, M. Balasubramanian, D. Lu, R. G. Nuzzo, A. I.
Frenkel
*Local structure and electronic state of atomically dispersed Pt on
nanosized CeO2 support*
ACS Catalysis *9*, 8738-8748 (2019)
https://you.stonybrook.edu/frenkel/files/2019/08/Pt-SAC-1.pdf
Regards,
Anatoly
********
On sabbatical leave at PSI, Switzerland.
********
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Anatoly I. Frenkel
Professor
Department of Materials Science and Chemical Engineering (primary
appointment)
Department of Chemistry (affiliate appointment)
* Stony Brook University *
Stony Brook, NY 11794
Email: anatoly.frenkel@stonybrook.edu
https://mail.bnl.gov/OWA/redir.aspx?C=F6wCGt4adziN6IvpdRQ-rWdgy3Oaoif_x-0ybKTBGBlALcrWeszTCA..&URL=mailto%3ajgchen%40columbia.edu
http://you.stonybrook.edu/frenkel
Co-Director and Spokesperson, Synchrotron Catalysis Consortium (SCC) at BNL
http://you.stonybrook.edu/scc2
Joint Appointment:
Senior Chemist
Chemistry Division, *Brookhaven National Laboratory*
Upton, NY 11973
Email: frenkel@bnl.gov
https://www.bnl.gov/staff/frenkel
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On Thu, Feb 8, 2024 at 2:08 PM Qiang
Hi everyone,
I would like to have a discussion about the common EXAFS for single atom catalysts. It is usually observed that there is only one strong peak around 1.5A in EXAFS, and it is attributed to the nearest neighbors of O or N. Take an example of Pt1/CeO2 catalyst. Pt single atom is coordinated with a few oxygens, i.e., PtOx. These oxygens constitute the first shell of Pt. It is supposed that these O should also attach to the metal element of the support (Ce here). So there is also Pt-O-Ce structure. Why it doesnot have strong scattering peak in EXAFS? Is it that because the Pt-O-Ce formed is not ordered, or it is actually not a bond just some weak contact?
Thank you very much.
Qiang
_______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit
Hi Qiang:
It is exactly as you say. The number of metal-metal paths is small and not
well ordered. This washes out the scattering significantly. If the Pt is
in a more rigid well-ordered structure the second "shell" path is generally
more visible.
Carlo
On Thu, Feb 8, 2024 at 1:08 PM Qiang
Hi everyone,
I would like to have a discussion about the common EXAFS for single atom catalysts. It is usually observed that there is only one strong peak around 1.5A in EXAFS, and it is attributed to the nearest neighbors of O or N. Take an example of Pt1/CeO2 catalyst. Pt single atom is coordinated with a few oxygens, i.e., PtOx. These oxygens constitute the first shell of Pt. It is supposed that these O should also attach to the metal element of the support (Ce here). So there is also Pt-O-Ce structure. Why it doesnot have strong scattering peak in EXAFS? Is it that because the Pt-O-Ce formed is not ordered, or it is actually not a bond just some weak contact?
Thank you very much.
Qiang
_______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit
-- Carlo U. Segre (he/him) -- Duchossois Leadership Professor of Physics Professor of Materials Science & Engineering Director, Center for Synchrotron Radiation Research and Instrumentation Illinois Institute of Technology Phone: 312.567.3498 segre@iit.edu http://phys.iit.edu/~segre segre@debian.org
participants (3)
-
Anatoly Frenkel -
Carlo Segre -
Qiang