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Title: Sintering of Pt nanoparticles via volatile PtO 2: Simulation and comparison with experiments

Abstract

It is a longstanding question whether sintering of platinum under oxidizing conditions is mediated by surface migration of Pt species or through the gas phase, by PtO 2(g). Clearly, a rational approach to avoid sintering requires understanding the underlying mechanism. A basic theory for the simulation of ripening through the vapor phase has been derived by Wynblatt and Gjostein. Recent modeling efforts, however, have focused entirely on surface-mediated ripening. In this work, we explicitly model ripening through PtO 2(g) and study how oxygen pressure, temperature, and shape of the particle size distribution affect sintering. On the basis of the available data on α-quartz, adsorption of monomeric Pt species on the support is extremely weak and has therefore not been explicitly simulated, while this may be important for more strongly interacting supports. Our simulations clearly show that ripening through the gas phase is predicted to be relevant. Assuming clean Pt particles, sintering is generally overestimated. This can be remedied by explicitly including oxygen coverage effects that lower both surface free energies and the sticking coefficient of PtO 2(g). Additionally, mass-transport limitations in the gas phase may play a role. Using a parameterization that accounts for these effects, we can quantitatively reproducemore » a number of experiments from the literature, including pressure and temperature dependence. Lastly, this substantiates the hypothesis of ripening via PtO 2(g) as an alternative to surface-mediated ripening.« less

Authors:
 [1];  [2]
  1. SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Institute of Catalysis Research and Technology (IKFT), Leopoldshafen (Germany)
  2. SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1349298
Grant/Contract Number:
AC02-76SF00515
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
ACS Catalysis
Additional Journal Information:
Journal Volume: 6; Journal Issue: 10; Journal ID: ISSN 2155-5435
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; adsorbates; BEP; catalysis; DFT; transition state

Citation Formats

Plessow, Philipp N., and Abild-Pedersen, Frank. Sintering of Pt nanoparticles via volatile PtO2: Simulation and comparison with experiments. United States: N. p., 2016. Web. doi:10.1021/acscatal.6b01646.
Plessow, Philipp N., & Abild-Pedersen, Frank. Sintering of Pt nanoparticles via volatile PtO2: Simulation and comparison with experiments. United States. doi:10.1021/acscatal.6b01646.
Plessow, Philipp N., and Abild-Pedersen, Frank. 2016. "Sintering of Pt nanoparticles via volatile PtO2: Simulation and comparison with experiments". United States. doi:10.1021/acscatal.6b01646. https://www.osti.gov/servlets/purl/1349298.
@article{osti_1349298,
title = {Sintering of Pt nanoparticles via volatile PtO2: Simulation and comparison with experiments},
author = {Plessow, Philipp N. and Abild-Pedersen, Frank},
abstractNote = {It is a longstanding question whether sintering of platinum under oxidizing conditions is mediated by surface migration of Pt species or through the gas phase, by PtO2(g). Clearly, a rational approach to avoid sintering requires understanding the underlying mechanism. A basic theory for the simulation of ripening through the vapor phase has been derived by Wynblatt and Gjostein. Recent modeling efforts, however, have focused entirely on surface-mediated ripening. In this work, we explicitly model ripening through PtO2(g) and study how oxygen pressure, temperature, and shape of the particle size distribution affect sintering. On the basis of the available data on α-quartz, adsorption of monomeric Pt species on the support is extremely weak and has therefore not been explicitly simulated, while this may be important for more strongly interacting supports. Our simulations clearly show that ripening through the gas phase is predicted to be relevant. Assuming clean Pt particles, sintering is generally overestimated. This can be remedied by explicitly including oxygen coverage effects that lower both surface free energies and the sticking coefficient of PtO2(g). Additionally, mass-transport limitations in the gas phase may play a role. Using a parameterization that accounts for these effects, we can quantitatively reproduce a number of experiments from the literature, including pressure and temperature dependence. Lastly, this substantiates the hypothesis of ripening via PtO2(g) as an alternative to surface-mediated ripening.},
doi = {10.1021/acscatal.6b01646},
journal = {ACS Catalysis},
number = 10,
volume = 6,
place = {United States},
year = 2016,
month = 9
}

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