Ab Initio Molecular Dynamics Study of Pt Clustering on γ-Al2O3 and Sn-Modified γ-Al2O3
Date
2023-10-05
Journal Title
Journal ISSN
Volume Title
Publisher
Journal of Physical Chemistry C
Abstract
We have conducted AIMD free energy simulations to examine the dynamics of Pt atoms and Ptn (n = 2–3) species on dry γ-Al2O3(100), dry γ-Al2O3(110), and wet γ-Al2O3(110) surfaces, with OH coverages corresponding to 500 K (11.8 OH/nm2) and 800 K (5.9 OH/nm2), while varying the Pt and Sn loading. Under the same dry conditions and temperature, comparing the (100) and (110) surface terminations revealed that the interactions between Pt and the surface play a crucial role in determining whether the potential of mean force between reduced Pt atoms is repulsive, as observed on the (100) surface, or if it can support a bound Pt–Pt state, as observed on the (110) surface. The hydration of the (110) surface had a significant impact. At a Pt loading of 0.75 Pt/nm2, with hydration of 5.9 OH/nm2, the energy of the potential of mean force increases. Although a Pt–Pt bound state is still supported, it becomes kinetically less accessible from the dispersed state. At an even higher water loading of 11.8 OH/nm2, the Pt–Pt potential of mean force becomes predominantly repulsive and can no longer sustain the Pt–Pt bound state. Higher Pt loadings of 1.12 Pt atoms/nm2 promote the aggregation of Pt into progressively larger clusters, but high levels of hydration can kinetically impede particle growth. On Sn-modified γ-Al2O3(110), Pt tends to associate with Sn, except at high levels of surface hydration where the potential of mean force between Pt and Sn atoms becomes repulsive. The presence of Sn inhibits the aggregation of Pt particles, and the Pt–Pt potential of mean force becomes increasingly repulsive with higher Sn loading.
Description
This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in Journal of Physical Chemistry C, copyright © 2023 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work seehttps://doi.org/10.1021/acs.jpcc.3c04595. This article will be embargoed until 10/05/2024.
Keywords
colloids, free energy, hydration, nucleation, platinum
Citation
Chen, Tso-Hsuan, Dionisios G. Vlachos, and Stavros Caratzoulas. “Ab Initio Molecular Dynamics Study of Pt Clustering on γ-Al 2 O 3 and Sn-Modified γ-Al 2 O 3.” The Journal of Physical Chemistry C 127, no. 39 (October 5, 2023): 19778–87. https://doi.org/10.1021/acs.jpcc.3c04595.