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Chung S, Schober JC, Tober S, Schmidt D, Khadiev A, Novikov DV, Vonk V, Stierle A. Epitaxy and Shape Heterogeneity of a Nanoparticle Ensemble during Redox Cycles. ACS NANO 2021; 15:13267-13278. [PMID: 34350766 DOI: 10.1021/acsnano.1c03002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The role of metal-support epitaxy on shape and size heterogeneity of nanoparticles and their response to gas atmospheres is not very well explored. Here we show that an ensemble of Pd nanoparticles, grown on MgO(001) by deposition under ultrahigh vacuum, mostly consists of two distinctly epitaxially oriented particles, each having a different structural response to redox cycles. X-ray reciprocal space patterns were acquired in situ under oxidizing and reducing environments. Each type of nanoparticle has a truncated octahedral shape, whereby the majority grows with a cube-on-cube epitaxy on the substrate. Less frequently occurring and larger particles have their principal crystal axes rotated ±3.7° with respect to the substrate's. Upon oxidation, the top (001) facets of both types of particles shrink. The relative change of the rotated particles' top facets is much more pronounced. This finding indicates that a larger mass transfer is involved for the rotated particles and that a larger portion of high-index facets forms. On the main facets of the cube-on-cube particles, the oxidation process results in a considerable strain, as concluded from the evolution to largely asymmetric facet scattering signals. The shape and strain responses are reversible upon reduction, either by annealing to 973 K in vacuum or by reducing with hydrogen. The presented results are important for unraveling different elements of heterogeneity and their effect on the performance of real polycrystalline catalysts. It is shown that a correlation can exist between the particle-support epitaxy and redox-cycling-induced shape changes.
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Affiliation(s)
- Simon Chung
- CXNS - Center for X-ray and Nano Science, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - Jan-Christian Schober
- CXNS - Center for X-ray and Nano Science, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
- Fachbereich Physik, Universität Hamburg, Jungiusstrasse 11, 20355 Hamburg, Germany
| | - Steffen Tober
- CXNS - Center for X-ray and Nano Science, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
- Fachbereich Physik, Universität Hamburg, Jungiusstrasse 11, 20355 Hamburg, Germany
| | - Daniel Schmidt
- Fachbereich Physik, Universität Hamburg, Jungiusstrasse 11, 20355 Hamburg, Germany
| | - Azat Khadiev
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - Dmitri V Novikov
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - Vedran Vonk
- CXNS - Center for X-ray and Nano Science, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - Andreas Stierle
- CXNS - Center for X-ray and Nano Science, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
- Fachbereich Physik, Universität Hamburg, Jungiusstrasse 11, 20355 Hamburg, Germany
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Farkaš B, de Leeuw NH. A Perspective on Modelling Metallic Magnetic Nanoparticles in Biomedicine: From Monometals to Nanoalloys and Ligand-Protected Particles. MATERIALS (BASEL, SWITZERLAND) 2021; 14:3611. [PMID: 34203371 PMCID: PMC8269646 DOI: 10.3390/ma14133611] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 06/17/2021] [Accepted: 06/21/2021] [Indexed: 12/24/2022]
Abstract
The focus of this review is on the physical and magnetic properties that are related to the efficiency of monometallic magnetic nanoparticles used in biomedical applications, such as magnetic resonance imaging (MRI) or magnetic nanoparticle hyperthermia, and how to model these by theoretical methods, where the discussion is based on the example of cobalt nanoparticles. Different simulation systems (cluster, extended slab, and nanoparticle models) are critically appraised for their efficacy in the determination of reactivity, magnetic behaviour, and ligand-induced modifications of relevant properties. Simulations of the effects of nanoscale alloying with other metallic phases are also briefly reviewed.
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Affiliation(s)
- Barbara Farkaš
- School of Chemistry, Cardiff University, Cardiff CF10 3AT, UK;
| | - Nora H. de Leeuw
- School of Chemistry, Cardiff University, Cardiff CF10 3AT, UK;
- School of Chemistry, University of Leeds, Leeds LS2 9JT, UK
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Ahmadi M, Timoshenko J, Behafarid F, Roldan Cuenya B. Tuning the Structure of Pt Nanoparticles through Support Interactions: An in Situ Polarized X-ray Absorption Study Coupled with Atomistic Simulations. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2019; 123:10666-10676. [PMID: 31049123 PMCID: PMC6487391 DOI: 10.1021/acs.jpcc.9b00945] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 03/25/2019] [Indexed: 05/31/2023]
Abstract
Interactions of nanoparticles (NPs) with their environment may have a pronounced effect on their structure and shape as well as on their functionality in applications such as catalysis. It is therefore crucial to disentangle the particle-adsorbate and particle-support interaction effects on the particle shape, its local structure, atomic dynamics, and its possible anisotropies. In order to gain insight into the support effect, we carried out an X-ray absorption fine-structure spectroscopy (XAFS) investigation of adsorbate- and ligand-free size-selected Pt NPs deposited on two different supports in ultrahigh vacuum. Polarization-dependent XAFS measurements, neural network-based analysis of X-ray absorption near-edge structure data, and reverse Monte Carlo (RMC) simulations of extended X-ray absorption fine structure (EXAFS) were used to resolve the 3D shape of the NPs and details of their local structure. A synergetic combination of advanced in situ XAFS analysis with atomic force microscopy and scanning tunneling microscopy (STM) imaging provides uniquely detailed information about the particle-support interactions and the NP/support buried interface, not accessible to any experimental technique, when considered alone. In particular, our combined approach reveals differences in the structure of Pt NPs deposited on TiO2(110) and SiO2/Si(111). Pt NPs on SiO2 assume a spherical-like 3D shape and weakly interact with the support. In contrast, the effective shape of analogously synthesized Pt NPs on TiO2(110) after annealing at 600 °C is found to be a truncated octahedron with (100) top and interfacial facets that are encapsulated by the TiO2 support. Modeling disorder effects in these NPs using an RMC approach reveals differences in bond-length distributions for NPs on different supports and allows us to analyze their anisotropy, which may be crucial for the interpretation of support-dependent atomic dynamics and can have an impact on the understanding of the catalytic properties of these NPs.
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Affiliation(s)
- M. Ahmadi
- Department
of Physics, University of Central Florida, Orlando, Florida 32816, United States
| | - J. Timoshenko
- Department
of Interface Science, Fritz-Haber-Institute
of the Max Planck Society, 14195 Berlin, Germany
| | - F. Behafarid
- Department
of Physics, University of Central Florida, Orlando, Florida 32816, United States
| | - B. Roldan Cuenya
- Department
of Physics, University of Central Florida, Orlando, Florida 32816, United States
- Department
of Interface Science, Fritz-Haber-Institute
of the Max Planck Society, 14195 Berlin, Germany
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4
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Ahmadi M, Behafarid F, Cuenya BR. Size-dependent adhesion energy of shape-selected Pd and Pt nanoparticles. NANOSCALE 2016; 8:11635-11641. [PMID: 27216883 DOI: 10.1039/c6nr02166b] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Thermodynamically stable shape-selected Pt and Pd nanoparticles (NPs) were synthesized via inverse micelle encapsulation and a subsequent thermal treatment in vacuum above 1000 °C. The majority of the Pd NPs imaged via scanning tunneling microscopy (STM) had a truncated octahedron shape with (111) top and interfacial facets, while the Pt NPs were found to adopt a variety of shapes. For NPs of identical shape for both material systems, the NP-support adhesion energy calculated based on STM data was found to be size-dependent, with large NPs (e.g. ∼6 nm) having lower adhesion energies than smaller NPs (e.g. ∼1 nm). This phenomenon was rationalized based on support-induced strain that for larger NPs favors the formation of lattice dislocations at the interface rather than a lattice distortion that may propagate through the smaller NPs. In addition, identically prepared Pt NPs of the same shape were found to display a lower adhesion energy compared to Pd NPs. While in both cases, a transition from a lattice distortion to interface dislocations is expected to occur with increasing NP size, the higher elastic energy in Pt leads to a lower transition size, which in turn lowers the adhesion energy of Pt NPs compared to Pd.
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Affiliation(s)
- M Ahmadi
- Department of Physics, University of Central Florida, Orlando, FL 32816, USA
| | - F Behafarid
- Department of Physics, University of Central Florida, Orlando, FL 32816, USA
| | - B Roldan Cuenya
- Department of Physics, Ruhr-University Bochum, 44780 Bochum, Germany.
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5
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Hejral U, Müller P, Balmes O, Pontoni D, Stierle A. Tracking the shape-dependent sintering of platinum-rhodium model catalysts under operando conditions. Nat Commun 2016; 7:10964. [PMID: 26957204 PMCID: PMC4786879 DOI: 10.1038/ncomms10964] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 02/05/2016] [Indexed: 11/17/2022] Open
Abstract
Nanoparticle sintering during catalytic reactions is a major cause for catalyst deactivation. Understanding its atomic-scale processes and finding strategies to reduce it is of paramount scientific and economic interest. Here, we report on the composition-dependent three-dimensional restructuring of epitaxial platinum–rhodium alloy nanoparticles on alumina during carbon monoxide oxidation at 550 K and near-atmospheric pressures employing in situ high-energy grazing incidence x-ray diffraction, online mass spectrometry and a combinatorial sample design. For platinum-rich particles our results disclose a dramatic reaction-induced height increase, accompanied by a corresponding reduction of the total particle surface coverage. We find this restructuring to be progressively reduced for particles with increasing rhodium composition. We explain our observations by a carbon monoxide oxidation promoted non-classical Ostwald ripening process during which smaller particles are destabilized by the heat of reaction. Its driving force lies in the initial particle shape which features for platinum-rich particles a kinetically stabilized, low aspect ratio. Understanding nanoparticle sintering is crucial for designing stable catalysts. Here, the authors use high energy grazing incidence X-ray diffraction as an in situ probe to track the compositiondependent three-dimensional restructuring of supported alloy nanoparticles during carbon monoxide oxidation.
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Affiliation(s)
- Uta Hejral
- Deutsches Elektronen-Synchrotron (DESY), NanoLab, Notkestrasse 85, D-22607 Hamburg, Germany.,Universität Hamburg, Fachbereich Physik, Jungiusstraße 9, 20355 Hamburg, Germany.,Universität Siegen, Fachbereich Physik, Walter-Flex-Straße 3, 57072 Siegen, Germany
| | - Patrick Müller
- Deutsches Elektronen-Synchrotron (DESY), NanoLab, Notkestrasse 85, D-22607 Hamburg, Germany.,Universität Hamburg, Fachbereich Physik, Jungiusstraße 9, 20355 Hamburg, Germany.,Universität Siegen, Fachbereich Physik, Walter-Flex-Straße 3, 57072 Siegen, Germany
| | - Olivier Balmes
- MAX IV Laboratory, Fotongatan 2, 22594 Lund, Sweden.,ESRF - The European Synchrotron, Radiation Facility, 71 Avenue des Martyrs, 38043 Grenoble, France
| | - Diego Pontoni
- ESRF - The European Synchrotron, Radiation Facility, 71 Avenue des Martyrs, 38043 Grenoble, France
| | - Andreas Stierle
- Deutsches Elektronen-Synchrotron (DESY), NanoLab, Notkestrasse 85, D-22607 Hamburg, Germany.,Universität Hamburg, Fachbereich Physik, Jungiusstraße 9, 20355 Hamburg, Germany.,Universität Siegen, Fachbereich Physik, Walter-Flex-Straße 3, 57072 Siegen, Germany
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6
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Furukawa S, Ochi K, Luo H, Miyazaki M, Komatsu T. Selective Stereochemical Catalysis Controlled by Specific Atomic Arrangement of Ordered Alloys. ChemCatChem 2015. [DOI: 10.1002/cctc.201500808] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Shinya Furukawa
- Department of Chemistry; Graduate School of Science and Engineering; Tokyo Institute of Technology; 2-12-1-E1-10, Ookayama, Meguro-ku Tokyo 152-8550 Japan
| | - Kazuyoshi Ochi
- Department of Chemistry; Graduate School of Science and Engineering; Tokyo Institute of Technology; 2-12-1-E1-10, Ookayama, Meguro-ku Tokyo 152-8550 Japan
| | - Hui Luo
- Department of Chemistry; Graduate School of Science and Engineering; Tokyo Institute of Technology; 2-12-1-E1-10, Ookayama, Meguro-ku Tokyo 152-8550 Japan
| | - Masayoshi Miyazaki
- Department of Chemistry; Graduate School of Science and Engineering; Tokyo Institute of Technology; 2-12-1-E1-10, Ookayama, Meguro-ku Tokyo 152-8550 Japan
| | - Takayuki Komatsu
- Department of Chemistry; Graduate School of Science and Engineering; Tokyo Institute of Technology; 2-12-1-E1-10, Ookayama, Meguro-ku Tokyo 152-8550 Japan
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7
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Popa C, Zhu T, Tranca I, Kaghazchi P, Jacob T, Hensen EJM. Structure of palladium nanoparticles under oxidative conditions. Phys Chem Chem Phys 2015; 17:2268-73. [PMID: 25486336 DOI: 10.1039/c4cp01761g] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Using density functional theory (DFT) and thermodynamic considerations we study the shape and stability of Pd nanoparticles in oxygen-lean and oxygen-rich atmospheres. We find that at very high oxygen coverage cubes exposing (100) faces will form, which are stabilized due to the formation of a O/(√5 × √5)R27° overlayer. The shape of oxygen-covered Pd and Pt nanoparticles is compared in this study.
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Affiliation(s)
- Cristina Popa
- Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands.
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8
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Ogata Y, Koshida K, Mizutani G. Crystalline Pd nanowires on the MgO(210) faceted template. SURF INTERFACE ANAL 2014. [DOI: 10.1002/sia.5593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Yoichi Ogata
- Japan advanced Institute of Science and Technology; 1-1 Asahidai, Nomi Ishikawa 923-1292 Japan
| | - Kosuke Koshida
- Japan advanced Institute of Science and Technology; 1-1 Asahidai, Nomi Ishikawa 923-1292 Japan
| | - Goro Mizutani
- Japan advanced Institute of Science and Technology; 1-1 Asahidai, Nomi Ishikawa 923-1292 Japan
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9
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10
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Campbell CT, Sellers JRV. Enthalpies and entropies of adsorption on well-defined oxide surfaces: experimental measurements. Chem Rev 2013; 113:4106-35. [PMID: 23441680 DOI: 10.1021/cr300329s] [Citation(s) in RCA: 130] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Charles T Campbell
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, USA.
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11
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Viswanathan V, Wang FYF. Theoretical analysis of the effect of particle size and support on the kinetics of oxygen reduction reaction on platinum nanoparticles. NANOSCALE 2012; 4:5110-7. [PMID: 22785611 DOI: 10.1039/c2nr30572k] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
We perform a first-principles based computational analysis of the effect of particle size and support material on the electrocatalytic activity of platinum nanoparticles. Using a mechanism for oxygen reduction that accounts for electric field effects and stabilization from the water layer on the (111) and (100) facets, we show that the model used agrees well with linear sweep voltammetry and rotating ring disk electrode experiments. We find that the per-site activity of the nanoparticle saturates for particles larger than 5 nm and we show that the optimal particle size is in the range of 2.5-3.5 nm, which agrees well with recent experimental work. We examine the effect of support material and show that the perimeter sites on the metal-support interface are important in determining the overall activity of the nanoparticles. We also develop simple geometric estimates for the activity which can be used for determining the activity of other particle shapes and sizes.
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12
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Moseler M, Walter M, Yoon B, Landman U, Habibpour V, Harding C, Kunz S, Heiz U. Oxidation state and symmetry of magnesia-supported Pd13O(x) nanocatalysts influence activation barriers of CO oxidation. J Am Chem Soc 2012; 134:7690-9. [PMID: 22519644 DOI: 10.1021/ja211121m] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Combining temperature-programmed reaction measurements, isotopic labeling experiments, and first-principles spin density functional theory, the dependence of the reaction temperature of catalyzed carbon monoxide oxidation on the oxidation state of Pd(13) clusters deposited on MgO surfaces grown on Mo(100) is explored. It is shown that molecular oxygen dissociates easily on the supported Pd(13) cluster, leading to facile partial oxidation to form Pd(13)O(4) clusters with C(4v) symmetry. Increasing the oxidation temperature to 370 K results in nonsymmetric Pd(13)O(6) clusters. The higher symmetry, partially oxidized cluster is characterized by a relatively high activation energy for catalyzed combustion of the first CO molecule via a reaction of an adsorbed CO molecule with one of the oxygen atoms of the Pd(13)O(4) cluster. Subsequent reactions on the resulting lower-symmetry Pd(13)O(x) (x < 4) clusters entail lower activation energies. The nonsymmetric Pd(13)O(6) clusters show lower temperature-catalyzed CO combustion, already starting at cryogenic temperature.
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Affiliation(s)
- Michael Moseler
- Freiburg Materials Research Center, University of Freiburg, Stefan-Meier-Strasse 21, 79104 Freiburg, Germany.
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13
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Nolte P, Stierle A, Kasper N, Jin-Phillipp NY, Jeutter N, Dosch H. Reversible shape changes of Pd nanoparticles on MgO(100). NANO LETTERS 2011; 11:4697-700. [PMID: 21995433 DOI: 10.1021/nl2023564] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
We studied the interaction of oxygen with MgO(100) supported Pd nanoparticles at 10(-5) mbar oxygen pressure and a sample temperature of 570 K. We employed high-resolution X-ray reciprocal space mapping, which allows us to resolve the average particle shape from the quantitative analysis of intensity diffraction rods running perpendicular to corresponding facet surfaces. We identified the oxygen induced formation of nanosized (112) facets which is reversible in a CO atmosphere. Our results give direct evidence for the microscopic evolution of the nanoparticle shape under reactant exposure, which is essential for an atomistic understanding of catalytic reactions on nanoparticles.
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Affiliation(s)
- Philipp Nolte
- Max-Planck-Institut für Metallforschung, 70569 Stuttgart, Germany
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15
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Seriani N, Pompe W, Ciacchi LC. Catalytic Oxidation Activity of Pt3O4 Surfaces and Thin Films. J Phys Chem B 2006; 110:14860-9. [PMID: 16869596 DOI: 10.1021/jp063281r] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The catalytic oxidation activity of platinum particles in automobile catalysts is thought to originate from the presence of highly reactive superficial oxide phases which form under oxygen-rich reaction conditions. Here we study the thermodynamic stability of platinum oxide surfaces and thin films and their reactivities toward oxidation of carbon compounds by means of first-principles atomistic thermodynamics calculations and molecular dynamics simulations based on density functional theory. On the Pt(111) surface the most stable superficial oxide phase is found to be a thin layer of alpha-PtO2, which appears not to be reactive toward either methane dissociation or carbon monoxide oxidation. A PtO-like structure is most stable on the Pt(100) surface at oxygen coverages of one monolayer, while the formation of a coherent and stress-free Pt3O4 film is favored at higher coverages. Bulk Pt3O4 is found to be thermodynamically stable in a region around 900 K at atmospheric pressure. The computed net driving force for the dissociation of methane on the Pt3O4(100) surface is much larger than that on all other metallic and oxide surfaces investigated. Moreover, the enthalpy barrier for the adsorption of CO molecules on oxygen atoms of this surface is as low as 0.34 eV, and desorption of CO2 is observed to occur without any appreciable energy barrier in molecular dynamics simulations. These results, combined, indicate a high catalytic oxidation activity of Pt3O4 phases that can be relevant in the contexts of Pt-based automobile catalysts and gas sensors.
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Affiliation(s)
- Nicola Seriani
- Institut für Werkstoffwissenschaft, Technische Universität Dresden, Hallwachsstrasse 3, 01069 Dresden, Germany.
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16
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Sao-Joao S, Giorgio S, Penisson JM, Chapon C, Bourgeois S, Henry C. Structure and Deformations of Pd−Ni Core−Shell Nanoparticles. J Phys Chem B 2005; 109:342-7. [PMID: 16851020 DOI: 10.1021/jp040473i] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Homogeneous collections of Pd-Ni core-shell nanoparticles have been prepared by decomposition of metal-organic compounds and studied by several electron microscopy techniques: transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM), energy-filtered microscopy (EFTEM), and by X-ray photoelectron spectroscopy (XPS). The physical and chemical properties of the Pd shell are supposed to depend on its electronic properties, which are influenced by the presence of the Ni core and by the deformation in the Pd lattice. Here, the interfacial structure of Pd/Ni and the lattice deformations in the core and the shell are studied in detail. The catalytic properties of the pure metal and the bimetallic particles, toward CO oxidation, have been investigated.
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Affiliation(s)
- S Sao-Joao
- CRMCN-CNRS, Campus de Luminy, Case 913, 13288 Marseille Cédex 9, France
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17
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Koplitz LV, Dulub O, Diebold U. STM Study of Copper Growth on ZnO(0001)−Zn and ZnO(0001̄)−O Surfaces. J Phys Chem B 2003. [DOI: 10.1021/jp0352175] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lynn Vogel Koplitz
- Department of Chemistry, Loyola University, New Orleans, Louisiana 70118, and Department of Physics, Tulane University, New Orleans, Louisiana 70118
| | - Olga Dulub
- Department of Chemistry, Loyola University, New Orleans, Louisiana 70118, and Department of Physics, Tulane University, New Orleans, Louisiana 70118
| | - Ulrike Diebold
- Department of Chemistry, Loyola University, New Orleans, Louisiana 70118, and Department of Physics, Tulane University, New Orleans, Louisiana 70118
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18
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Filankembo A, Giorgio S, Lisiecki I, Pileni MP. Is the Anion the Major Parameter in the Shape Control of Nanocrystals? J Phys Chem B 2003. [DOI: 10.1021/jp022282q] [Citation(s) in RCA: 198] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- A. Filankembo
- Laboratoire L.M.2.N., U.M.R. C.N.R.S. 7070, Université Pierre et Marie Curie (Paris VI), B.P. 52, 4 Place Jussieu, F-752 31 Paris Cedex 05, France, and CRMC2-CNRS, Campus de Luminy, Case 913, 13288 Marseille Cedex 9, France
| | - S. Giorgio
- Laboratoire L.M.2.N., U.M.R. C.N.R.S. 7070, Université Pierre et Marie Curie (Paris VI), B.P. 52, 4 Place Jussieu, F-752 31 Paris Cedex 05, France, and CRMC2-CNRS, Campus de Luminy, Case 913, 13288 Marseille Cedex 9, France
| | - I. Lisiecki
- Laboratoire L.M.2.N., U.M.R. C.N.R.S. 7070, Université Pierre et Marie Curie (Paris VI), B.P. 52, 4 Place Jussieu, F-752 31 Paris Cedex 05, France, and CRMC2-CNRS, Campus de Luminy, Case 913, 13288 Marseille Cedex 9, France
| | - M. P. Pileni
- Laboratoire L.M.2.N., U.M.R. C.N.R.S. 7070, Université Pierre et Marie Curie (Paris VI), B.P. 52, 4 Place Jussieu, F-752 31 Paris Cedex 05, France, and CRMC2-CNRS, Campus de Luminy, Case 913, 13288 Marseille Cedex 9, France
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19
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Reaction dynamics on supported metal clusters. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s1571-0785(03)11009-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
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20
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Campbell CT, Parker SC, Starr DE. The effect of size-dependent nanoparticle energetics on catalyst sintering. Science 2002; 298:811-4. [PMID: 12399586 DOI: 10.1126/science.1075094] [Citation(s) in RCA: 515] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Calorimetric measurements of metal adsorption energies directly provide the energies of metal atoms in supported metal nanoparticles. As the metal coverage increases, the particles grow, revealing the dependence of this energy on particle size, which is found to be much stronger than predicted with the usual Gibbs-Thompson relation. It is shown that this knowledge is crucial to accurately model long-term sintering rates of metal nanoparticles in catalysts.
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Affiliation(s)
- Charles T Campbell
- Department of Chemistry, Box 351700, University of Washington, Seattle, WA 98195-1700, USA
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21
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Abstract
The calormetically measured heats of adsorption of Cu, Ag, and Pb on MgO(100), previously measured in our group, are correlated with bulk properties of the metals and their sticking probabilities and film morphologies. The low-coverage heats of adsorption (when the metals are mainly in two-dimensional (2D) islands) are used to estimate metal-MgO(100) bond energies within a pairwise bond additivity model. These values correlate well with the observed initial sticking probabilities and saturation island densities of the metals. This supports a transient mobile precursor model for adsorption. The values also correlate with their bulk sublimation energies, which suggests that covalent metal-Mg bonding dominates the interaction at low coverage, probably due to very strong bonding at defects. The heats of adsorption integrated up to multilayer coverages provide the metal-MgO(100) adhesion energies and metal-MgO(100) bond energies for metals in 3D films. These values correlate with the sum of magnitudes of the metal's bulk sublimation energy plus the heat of formation of the bulk oxide of the metal per mole of metal atoms. This suggests that local chemical bonds, both metal-oxygen and covalent metal-Mg, dominate the interfacial bonding for 3D films.
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Affiliation(s)
- Charles T Campbell
- Department of Chemistry, Box 351700, University of Washington, Seattle, Washington 98195-1700, USA.
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