Near-Ambient Pressure XPS and MS Study of CO Oxidation over Model Pd-Au/HOPG Catalysts: The Effect of the Metal Ratio | Sciact - CRIS-system of Boreskov Institute of Catalysis

Near-Ambient Pressure XPS and MS Study of CO Oxidation over Model Pd-Au/HOPG Catalysts: The Effect of the Metal Ratio Full article

Journal

Nanomaterials
, E-ISSN: 2079-4991

Output data

Year: 2021, Volume: 11, Article number : 3292, Pages count : 15 DOI: 10.3390/nano11123292

Tags

NAP XPS; bimetallic Pd-Au nanoparticles; CO oxidation; adsorption-induced segregation

Authors

Bukhtiyarov Andrey V. ¹ , Prosvirin Igor P. ² , Panafidin Maxim A. ¹ , Fedorov Alexey Yu. ^2,3 , Klyushin Alexander Yu. ^4,5 , Knop-Gericke Axel ^4,6 , Zubavichus Yan V. ¹ , Bukhtiyarov Valery I. ²

Affiliations

1	Synchrotron Radiation Facility SKIF, Boreskov Institute of Catalysis SB RAS, 630559 Kol’tsovo, Russia
2	Department of Physicochemical Techniques, Boreskov Institute of Catalysis SB RAS, 630090 Novosibirsk
3	Department of Natural Sciences, Novosibirsk State University, 630090 Novosibirsk
4	Inorganic Chemistry Department, Fritz Haber Institute of the Max Planck Society, 14195 Berlin, Germany
5	BESSY II, Helmholtz Center for Materials and Energy, 12489 Berlin, Germany
6	Department of Heterogeneous Reactions, Max Planck Institute for Chemical Energy Conversion, 45470 Mülheim an der Ruhr, Germany

Funding (1)

Ministry of Science and Higher Education of the Russian Federation

ГЗ-2021-2023

In this study, the dependence of the catalytic activity of highly oriented pyrolytic graphite (HOPG)-supported bimetallic Pd-Au catalysts towards the CO oxidation based on the Pd/Au atomic ratio was investigated. The activities of two model catalysts differing from each other in the initial Pd/Au atomic ratios appeared as distinctly different in terms of their ignition temperatures. More specifically, the PdAu-2 sample with a lower Pd/Au surface ratio (~0.75) was already active at temperatures less than 150 °C, while the PdAu-1 sample with a higher Pd/Au surface ratio (~1.0) became active only at temperatures above 200 °C. NAP XPS revealed that the exposure of the catalysts to a reaction mixture at RT induces the palladium surface segregation accompanied by an enrichment of the near-surface regions of the two-component Pd-Au alloy nanoparticles with Pd due to adsorption of CO on palladium atoms. The segregation extent depends on the initial Pd/Au surface ratio. The difference in activity between these two catalysts is determined by the presence or higher concentration of specific active Pd sites on the surface of bimetallic particles, i.e., by the ensemble effect. Upon cooling the sample down to room temperature, the reverse redistribution of the atomic composition within near-surface regions occurs, which switches the catalyst back into inactive state. This observation strongly suggests that the optimum active sites emerge under reaction conditions exclusively, involving both high temperature and a reactive atmosphere.

Bukhtiyarov A.V. , Prosvirin I.P. , Panafidin M.A. , Fedorov A.Y. , Klyushin A.Y. , Knop-Gericke A. , Zubavichus Y.V. , Bukhtiyarov V.I.
Near-Ambient Pressure XPS and MS Study of CO Oxidation over Model Pd-Au/HOPG Catalysts: The Effect of the Metal Ratio
Nanomaterials. 2021. V.11. 3292 :1-15. DOI: 10.3390/nano11123292 WOS Scopus РИНЦ ANCAN PMID OpenAlex publication_identifier_short.sciact_skif_identifier_type

Submitted:	Oct 29, 2021
Accepted:	Dec 2, 2021
Published print:	Dec 4, 2021
Published online:	Dec 4, 2021

Web of science:	WOS:000736883800001
Scopus:	2-s2.0-85120640464
Elibrary:	47539276
Chemical Abstracts:	2022:92076
Chemical Abstracts (print):	177:270955
PMID:	34947641
OpenAlex:	W4200485081
publication_identifier.sciact_skif_identifier_type:	502

DB	Citing
Scopus	4
Web of science	4
Elibrary	4
OpenAlex	4