Does Cluster Encapsulation Inhibit Sintering? Stabilization of Size-Selected Pt Clusters on Fe₃O₄(001) by SMSI.

Content Provider	Europe PMC
Author	Kaiser, Sebastian Plansky, Johanna Krinninger, Matthias Shavorskiy, Andrey Zhu, Suyun Heiz, Ueli Esch, Friedrich Lechner, Barbara A. J.
Copyright Year	2023
Abstract	The metastability of supported metal nanoparticles limitstheirapplication in heterogeneous catalysis at elevated temperatures dueto their tendency to sinter. One strategy to overcome these thermodynamiclimits on reducible oxide supports is encapsulation via strong metal–supportinteraction (SMSI). While annealing-induced encapsulation is a well-exploredphenomenon for extended nanoparticles, it is as yet unknown whetherthe same mechanisms hold for subnanometer clusters, where concomitantsintering and alloying might play a significant role. In this article,we explore the encapsulation and stability of size-selected Pt5, Pt10, and Pt19 clusters depositedon Fe3O4(001). In a multimodal approach usingtemperature-programmed desorption (TPD), X-ray photoelectron spectroscopy(XPS), and scanning tunneling microscopy (STM), we demonstrate thatSMSI indeed leads to the formation of a defective, FeO-like conglomerateencapsulating the clusters. By stepwise annealing up to 1023 K, weobserve the succession of encapsulation, cluster coalescence, andOstwald ripening, resulting in square-shaped crystalline Pt particles,independent of the initial cluster size. The respective sinteringonset temperatures scale with the cluster footprint and thus size.Remarkably, while small encapsulated clusters can still diffuse asa whole, atom detachment and thus Ostwald ripening are successfullysuppressed up to 823 K, i.e., 200 K above the Hüttig temperaturethat indicates the thermodynamic stability limit.
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Journal	ACS Catalysis [ACS Catal]
Volume Number	13
DOI	10.1021/acscatal.3c00448
PubMed Central reference number	PMC10167661
Issue Number	9
PubMed reference number	37180966
e-ISSN	21555435
Language	English
Publisher	American Chemical Society
Publisher Date	2023-04-21
Access Restriction	Open
Rights License	Permits non-commercial access and re-use, provided that author attribution and integrity are maintained; but does not permit creation of adaptations or other derivative works (https://creativecommons.org/licenses/by-nc-nd/4.0/). © 2023 The Authors. Published by American Chemical Society
Subject Keyword	size-selected clusters strong metal−supportinteraction sintering encapsulation heterogeneous catalysis scanning tunneling microscopy temperature-programmed desorption X-ray photoelectronspectroscopy
Content Type	Text
Resource Type	Article
Subject	Chemistry Catalysis