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Carl S, Will J, Madubuko N, Götz A, Przybilla T, Wu M, Raman N, Wirth J, Taccardi N, Zubiri BA, Haumann M, Wasserscheid P, Spiecker E. Structural Evolution of GaO x-Shell and Intermetallic Phases in Ga-Pt Supported Catalytically Active Liquid Metal Solutions. J Phys Chem Lett 2024; 15:4711-4720. [PMID: 38657124 DOI: 10.1021/acs.jpclett.3c03494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
We present a comprehensive scale-bridging characterization approach for supported catalytically active liquid metal solutions (SCALMS) which combines lab-based X-ray microscopy, nano X-ray computed tomography (nano-CT), and correlative analytical transmission electron microscopy. SCALMS catalysts consist of low-melting alloy particles and have demonstrated high catalytic activity, selectivity, and long-term stability in propane dehydrogenation (PDH). We established an identical-location nano-CT workflow which allows us to reveal site-specific changes of Ga-Pt SCALMS before and after PDH. These observations are complemented by analytical transmission electron microscopy investigations providing information on the structure, chemical composition, and phase distribution of individual SCALMS particles. Key findings of this combined microscopic approach include (i) structural evolution of the SCALMS particles' GaOx shell, (ii) Pt segregation toward the oxide shell leading to the formation of Ga-Pt intermetallic phases, and (iii) cracking of the oxide shell accompanied by the release of liquid Ga-Pt toward the porous support.
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Affiliation(s)
- S Carl
- Institute of Micro- and Nanostructure Research (IMN) & Center for Nanoanalysis and Electron Microscopy (CENEM), Interdisciplinary Center for Nanostructured Films (IZNF), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Cauerstraße 3, 91058 Erlangen, Germany
| | - J Will
- Institute of Micro- and Nanostructure Research (IMN) & Center for Nanoanalysis and Electron Microscopy (CENEM), Interdisciplinary Center for Nanostructured Films (IZNF), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Cauerstraße 3, 91058 Erlangen, Germany
| | - N Madubuko
- Lehrstuhl für Chemische Reaktionstechnik (CRT), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen, Germany
| | - A Götz
- Institute of Micro- and Nanostructure Research (IMN) & Center for Nanoanalysis and Electron Microscopy (CENEM), Interdisciplinary Center for Nanostructured Films (IZNF), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Cauerstraße 3, 91058 Erlangen, Germany
| | - T Przybilla
- Institute of Micro- and Nanostructure Research (IMN) & Center for Nanoanalysis and Electron Microscopy (CENEM), Interdisciplinary Center for Nanostructured Films (IZNF), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Cauerstraße 3, 91058 Erlangen, Germany
| | - M Wu
- Institute of Micro- and Nanostructure Research (IMN) & Center for Nanoanalysis and Electron Microscopy (CENEM), Interdisciplinary Center for Nanostructured Films (IZNF), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Cauerstraße 3, 91058 Erlangen, Germany
| | - N Raman
- Lehrstuhl für Chemische Reaktionstechnik (CRT), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen, Germany
| | - J Wirth
- Institute of Micro- and Nanostructure Research (IMN) & Center for Nanoanalysis and Electron Microscopy (CENEM), Interdisciplinary Center for Nanostructured Films (IZNF), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Cauerstraße 3, 91058 Erlangen, Germany
| | - N Taccardi
- Lehrstuhl für Chemische Reaktionstechnik (CRT), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen, Germany
| | - B Apeleo Zubiri
- Institute of Micro- and Nanostructure Research (IMN) & Center for Nanoanalysis and Electron Microscopy (CENEM), Interdisciplinary Center for Nanostructured Films (IZNF), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Cauerstraße 3, 91058 Erlangen, Germany
| | - M Haumann
- Lehrstuhl für Chemische Reaktionstechnik (CRT), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen, Germany
- Research Centre for Synthesis and Catalysis, Department of Chemistry, University of Johannesburg, P.O. Box 524, 2006 Auckland Park, South Africa
| | - P Wasserscheid
- Lehrstuhl für Chemische Reaktionstechnik (CRT), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen, Germany
- Helmholtz-Institute Erlangen-Nürnberg for Renewable Energy (IEK 11), Forschungszentrum Jülich GmbH, Egerlandstr. 3, 91058 Erlangen, Germany
| | - E Spiecker
- Institute of Micro- and Nanostructure Research (IMN) & Center for Nanoanalysis and Electron Microscopy (CENEM), Interdisciplinary Center for Nanostructured Films (IZNF), Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Cauerstraße 3, 91058 Erlangen, Germany
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2
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Hsieh TE, Frisch J, Wilks RG, Papp C, Bär M. Impact of Catalysis-Relevant Oxidation and Annealing Treatments on Nanostructured GaRh Alloys. ACS APPLIED MATERIALS & INTERFACES 2024; 16:19858-19865. [PMID: 38591845 DOI: 10.1021/acsami.4c02286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/10/2024]
Abstract
In this study, we examine the surface-derived electronic and chemical structures of nanostructured GaRh alloys as a model system for supported catalytically active liquid metal solutions (SCALMS), a novel catalyst candidate for dehydrogenation reactions that are important for the petrochemical and hydrogen energy industry. It is reported that under ambient conditions, SCALMS tends to form a gallium oxide shell, which can be removed by an activation treatment at elevated temperatures and hydrogen flow to enhance the catalytic reactivity. We prepared a 7 at. % Rh containing the GaRh sample and interrogated the evolution of the surface chemical and electronic structure by photoelectron spectroscopy (complemented by scanning electron microscopy) upon performing surface oxidation and (activation treatment mimicking) annealing treatments in ultrahigh vacuum conditions. The initially pronounced Rh 4d and Fermi level-derived states in the valence band spectra disappear upon oxidation (due to formation of a GaOx shell) but reemerge upon annealing, especially for temperatures of 600 °C and above, i.e., when the GaOx shell is efficiently being removed and the Ga matrix is expected to be liquid. At the same temperature, new spectroscopic features at both the high and low binding energy sides of the Rh 3d5/2 spectra are observed, which we attribute to new GaRh species with depleted and enriched Rh contents, respectively. A liquefied and GaOx-free surface is also expected for GaRh SCALMS at reaction conditions, and thus the revealed high-temperature properties of the GaRh alloy provide insights about respective catalysts at work.
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Affiliation(s)
- Tzung-En Hsieh
- Department Interface Design, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), 12489 Berlin, Germany
| | - Johannes Frisch
- Department Interface Design, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), 12489 Berlin, Germany
- Energy Materials In-situ Laboratory Berlin (EMIL), HZB, 12489 Berlin, Germany
| | - Regan G Wilks
- Department Interface Design, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), 12489 Berlin, Germany
- Energy Materials In-situ Laboratory Berlin (EMIL), HZB, 12489 Berlin, Germany
| | - Christian Papp
- Freie Universität Berlin, Physical and Theoretical Chemistry, 14195Berlin, Germany
| | - Marcus Bär
- Department Interface Design, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), 12489 Berlin, Germany
- Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91058 Erlangen, Germany
- Energy Materials In-situ Laboratory Berlin (EMIL), HZB, 12489 Berlin, Germany
- Department X-ray Spectroscopy at Interfaces of Thin Films, Helmholtz-Institute Erlangen-Nürnberg for Renewable Energy (HI ERN), 12489 Berlin, Germany
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3
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Hsieh TE, Frisch J, Wilks RG, Bär M. Unravelling the Surface Oxidation-Induced Evolution of the Electronic Structure of Gallium. ACS APPLIED MATERIALS & INTERFACES 2023; 15:47725-47732. [PMID: 37774118 PMCID: PMC10571040 DOI: 10.1021/acsami.3c09324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Accepted: 09/18/2023] [Indexed: 10/01/2023]
Abstract
Gallium is widely used in liquid metal catalyst fabrication, and its oxidized species is a well-known dielectric material. In the past decades, these two species have been well studied separately. However, the surface oxide layer-induced impact on the chemical and electronic structure of (liquid) gallium is still mostly unclear because of the extreme fast formation of thermodynamically stable surface Ga2O3. In this study, we used a combination of direct and inverse photoemission complemented by scanning electron microscopy to examine the surface properties of Ga and Ga oxide (on a SiOx/Si support) and the evolution of the surface structure upon stepwise oxidation and subsequent reduction at an elevated temperature. We find oxidation time-dependent self-limited formation of a substoichiometric Ga2O3-δ surface layer on the Ga nanoparticles. The valence band maximum (conduction band minimum) for this Ga2O3-δ is located at -3.8 (±0.1) eV [1.4 (±0.2) eV] with respect to the Fermi level, resulting in an electronic surface band gap of 5.2 (±0.2) eV. Upon annealing in ultrahigh vacuum conditions, the Ga2O3-δ surface layer can efficiently be removed when using temperatures of 600 °C and higher. This study reveals how the surface properties of Ga nanoparticles are influenced by stepwise oxidation-reduction, providing detailed insights that will benefit the optimization of this material class for different applications.
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Affiliation(s)
- Tzung-En Hsieh
- Department
Interface Design, Helmholtz-Zentrum Berlin
für Materialien und Energie GmbH (HZB), 12489 Berlin, Germany
| | - Johannes Frisch
- Department
Interface Design, Helmholtz-Zentrum Berlin
für Materialien und Energie GmbH (HZB), 12489 Berlin, Germany
- Energy
Materials In situ Laboratory Berlin (EMIL), HZB, 12489 Berlin, Germany
| | - Regan G. Wilks
- Department
Interface Design, Helmholtz-Zentrum Berlin
für Materialien und Energie GmbH (HZB), 12489 Berlin, Germany
- Energy
Materials In situ Laboratory Berlin (EMIL), HZB, 12489 Berlin, Germany
| | - Marcus Bär
- Department
Interface Design, Helmholtz-Zentrum Berlin
für Materialien und Energie GmbH (HZB), 12489 Berlin, Germany
- Department
of Chemistry and Pharmacy, Friedrich-Alexander-Universität
Erlangen-Nürnberg (FAU), 91058 Erlangen, Germany
- Energy
Materials In situ Laboratory Berlin (EMIL), HZB, 12489 Berlin, Germany
- Department
X-ray Spectroscopy at Interfaces of Thin Films, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy
(HI ERN), 12489 Berlin, Germany
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Wittkämper H, Hock R, Weißer M, Dallmann J, Vogel C, Raman N, Tacardi N, Haumann M, Wasserscheid P, Hsieh TE, Maisel S, Moritz M, Wichmann C, Frisch J, Gorgoi M, Wilks RG, Bär M, Wu M, Spiecker E, Görling A, Unruh T, Steinrück HP, Papp C. Isolated Rh atoms in dehydrogenation catalysis. Sci Rep 2023; 13:4458. [PMID: 36932106 PMCID: PMC10023779 DOI: 10.1038/s41598-023-31157-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 03/07/2023] [Indexed: 03/19/2023] Open
Abstract
Isolated active sites have great potential to be highly efficient and stable in heterogeneous catalysis, while enabling low costs due to the low transition metal content. Herein, we present results on the synthesis, first catalytic trials, and characterization of the Ga9Rh2 phase and the hitherto not-studied Ga3Rh phase. We used XRD and TEM for structural characterization, and with XPS, EDX we accessed the chemical composition and electronic structure of the intermetallic compounds. In combination with catalytic tests of these phases in the challenging propane dehydrogenation and by DFT calculations, we obtain a comprehensive picture of these novel catalyst materials. Their specific crystallographic structure leads to isolated Rhodium sites, which is proposed to be the decisive factor for the catalytic properties of the systems.
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Affiliation(s)
- Haiko Wittkämper
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstr. 3, 91058, Erlangen, Germany
| | - Rainer Hock
- Lehrstuhl für Kristallographie und Strukturphysik, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Staudtstr. 3, 91058, Erlangen, Germany
| | - Matthias Weißer
- Lehrstuhl für Kristallographie und Strukturphysik, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Staudtstr. 3, 91058, Erlangen, Germany.
| | - Johannes Dallmann
- Lehrstuhl für Kristallographie und Strukturphysik, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Staudtstr. 3, 91058, Erlangen, Germany
| | - Carola Vogel
- Lehrstuhl für Kristallographie und Strukturphysik, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Staudtstr. 3, 91058, Erlangen, Germany
| | - Narayanan Raman
- Lehrstuhl für Chemische Reaktionstechnik (CRT), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstr. 3, 91058, Erlangen, Germany
| | - Nicola Tacardi
- Lehrstuhl für Chemische Reaktionstechnik (CRT), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstr. 3, 91058, Erlangen, Germany
| | - Marco Haumann
- Lehrstuhl für Chemische Reaktionstechnik (CRT), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstr. 3, 91058, Erlangen, Germany
| | - Peter Wasserscheid
- Lehrstuhl für Chemische Reaktionstechnik (CRT), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstr. 3, 91058, Erlangen, Germany.,Forschungszentrum Jülich GmbH, Helmholtz-Institute Erlangen-Nürnberg for Renewable Energy (IEK-11), Egerlandstr. 3, 91058, Erlangen, Germany
| | - Tzung-En Hsieh
- Department Interface Design, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), 12489, Berlin, Germany.,Energy Materials In-Situ Laboratory Berlin (EMIL), HZB, 12489, Berlin, Germany
| | - Sven Maisel
- Lehrstuhl für Theoretische Chemie, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstr. 3, 91058, Erlangen, Germany
| | - Michael Moritz
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstr. 3, 91058, Erlangen, Germany
| | - Christoph Wichmann
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstr. 3, 91058, Erlangen, Germany
| | - Johannes Frisch
- Department Interface Design, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), 12489, Berlin, Germany.,Energy Materials In-Situ Laboratory Berlin (EMIL), HZB, 12489, Berlin, Germany
| | - Mihaela Gorgoi
- Department Interface Design, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), 12489, Berlin, Germany.,Energy Materials In-Situ Laboratory Berlin (EMIL), HZB, 12489, Berlin, Germany
| | - Regan G Wilks
- Department Interface Design, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), 12489, Berlin, Germany.,Energy Materials In-Situ Laboratory Berlin (EMIL), HZB, 12489, Berlin, Germany
| | - Marcus Bär
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstr. 3, 91058, Erlangen, Germany.,Department Interface Design, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), 12489, Berlin, Germany.,Energy Materials In-Situ Laboratory Berlin (EMIL), HZB, 12489, Berlin, Germany.,Department X-Ray Spectroscopy at Interfaces of Thin Films, Helmholtz Institute for Renewable Energy (HI ERN), 12489, Berlin, Germany
| | - Mingjian Wu
- Lehrstuhl für Werkstoffwissenschaften (Mikro- und Nanostrukturforschung), Cauerstraße 3, 91058, Erlangen, Germany
| | - Erdmann Spiecker
- Lehrstuhl für Werkstoffwissenschaften (Mikro- und Nanostrukturforschung), Cauerstraße 3, 91058, Erlangen, Germany
| | - Andreas Görling
- Lehrstuhl für Theoretische Chemie, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstr. 3, 91058, Erlangen, Germany
| | - Tobias Unruh
- Lehrstuhl für Kristallographie und Strukturphysik, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Staudtstr. 3, 91058, Erlangen, Germany
| | - Hans-Peter Steinrück
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstr. 3, 91058, Erlangen, Germany
| | - Christian Papp
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstr. 3, 91058, Erlangen, Germany. .,Physikalische und Theoretische Chemie, Freie Universität Berlin, Arnimallee 22, 14195, Berlin, Germany.
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Yin P, Yang Y, Yan H, Wei M. Theoretical Calculations on Metal Catalysts Toward Water-Gas Shift Reaction: a Review. Chemistry 2023; 29:e202203781. [PMID: 36723438 DOI: 10.1002/chem.202203781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Accepted: 01/31/2023] [Indexed: 02/02/2023]
Abstract
Water-gas shift (WGS) reaction offers a dominating path to hydrogen generation from fossil fuel, in which heterogeneous metal catalysts play a crucial part in this course. This review highlights and summarizes recent developments on theoretical calculations of metal catalysts developed to date, including surface structure (e. g., monometallic and polymetallic systems) and interface structure (e. g., supported catalysts and metal oxide composites), with special emphasis on the characteristics of crystal-face effect, alloying strategy, and metal-support interaction. A systematic summarization on reaction mechanism was performed, including redox mechanism, associative mechanism as well as hybrid mechanism; the development on chemical kinetics (e. g., molecular dynamics, kinetic Monte Carlo and microkinetic simulation) was then introduced. At the end, challenges associated with theoretical calculations on metal catalysts toward WGS reaction are discussed and some perspectives on the future advance of this field are provided.
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Affiliation(s)
- Pan Yin
- State Key Laboratory of Chemical Resource Engineering, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China
- Institute of Engineering Technology, SINOPEC Catalyst Co., Ltd., Beijing, 110112, P. R. China
| | - Yusen Yang
- State Key Laboratory of Chemical Resource Engineering, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China
| | - Hong Yan
- State Key Laboratory of Chemical Resource Engineering, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China
| | - Min Wei
- State Key Laboratory of Chemical Resource Engineering, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China
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Hofer A, Taccardi N, Moritz M, Wichmann C, Hübner S, Drobek D, Engelhardt M, Papastavrou G, Spiecker E, Papp C, Wasserscheid P, Bachmann J. Preparation of geometrically highly controlled Ga particle arrays on quasi-planar nanostructured surfaces as a SCALMS model system. RSC Adv 2023; 13:4011-4018. [PMID: 36756587 PMCID: PMC9890623 DOI: 10.1039/d2ra07585g] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 01/23/2023] [Indexed: 01/28/2023] Open
Abstract
This study establishes a preparative route towards a model system for supported catalytically active liquid metal solutions (SCALMS) on nanostructured substrates. This model is characterized by a uniquely precise geometrical control of the gallium particle size distribution. In a SCALMS system, the Ga serves as a matrix material which can be decorated with a catalytically active material subsequently. The corresponding Ga containing precursor is spin-coated on aluminum based substrates, previously nanostructured by electrochemical anodization. The highly ordered substrates are functionalized with distinct oxide coatings by atomic layer deposition (ALD) independently from the morphology. After preparation of the metal particles on the oxide interface, the characterization of our model system in terms of its geometry parameters (droplet diameter, size distribution and population density) points to SiO2 as the best suited surface for a highly controlled geometry. This flexible model system can be functionalized with a dissolved noble metal catalyst for the application chosen.
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Affiliation(s)
- André Hofer
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Department of Chemistry and Pharmacy, Chemistry of Thin Film Materials, IZNF Cauerstr. 3 91058 Erlangen Germany
| | - Nicola Taccardi
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Department Chemical and Biological Engineering, Institute of Chemical Reaction Engineering (CRT)Egerlandstr. 391058 ErlangenGermany
| | - Michael Moritz
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Department of Chemistry and Pharmacy, Chair of Physical Chemistry IIEgerlandstr. 391058 ErlangenGermany
| | - Christoph Wichmann
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Department of Chemistry and Pharmacy, Chair of Physical Chemistry IIEgerlandstr. 391058 ErlangenGermany
| | - Sabine Hübner
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Institute of Micro- and Nanostructure Research (IMN) & Center for Nanoanalysis and Electron Microscopy (CENEM), IZNFCauerstr. 391058 ErlangenGermany
| | - Dominik Drobek
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Institute of Micro- and Nanostructure Research (IMN) & Center for Nanoanalysis and Electron Microscopy (CENEM), IZNFCauerstr. 391058 ErlangenGermany
| | - Matthias Engelhardt
- Universität Bayreuth, Chair of Physical Chemistry IIUniversitätsstr. 3095447 BayreuthGermany
| | - Georg Papastavrou
- Universität Bayreuth, Chair of Physical Chemistry IIUniversitätsstr. 3095447 BayreuthGermany
| | - Erdmann Spiecker
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Institute of Micro- and Nanostructure Research (IMN) & Center for Nanoanalysis and Electron Microscopy (CENEM), IZNFCauerstr. 391058 ErlangenGermany
| | - Christian Papp
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Department of Chemistry and Pharmacy, Chair of Physical Chemistry IIEgerlandstr. 391058 ErlangenGermany,Angewandte Physikalische Chemie, FU BerlinArnimalle 2214195 BerlinGermany
| | - Peter Wasserscheid
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Department Chemical and Biological Engineering, Institute of Chemical Reaction Engineering (CRT)Egerlandstr. 391058 ErlangenGermany,Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK-11)Cauerstr. 191058 ErlangenGermany
| | - Julien Bachmann
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Department of Chemistry and Pharmacy, Chemistry of Thin Film Materials, IZNF Cauerstr. 3 91058 Erlangen Germany
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7
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Sykes ECH, Christopher P, Li J. Fundamental insights into heterogeneous single-atom catalysis. J Chem Phys 2021; 155:210401. [PMID: 34879660 DOI: 10.1063/5.0073628] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- E Charles H Sykes
- Department of Chemistry, Tufts University, Medford, Massachusetts 02155, USA
| | - Phillip Christopher
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, USA
| | - Jun Li
- Department of Chemistry, Tsinghua University, Beijing 100084, China and Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, China
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8
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Abstract
Given the importance of catalysts in the chemical industry, they have been extensively investigated by experimental and numerical methods. With the development of computational algorithms and computer hardware, large-scale simulations have enabled influential studies with more atomic details reflecting microscopic mechanisms. This review provides a comprehensive summary of recent developments in molecular dynamics, including ab initio molecular dynamics and reaction force-field molecular dynamics. Recent research on both approaches to catalyst calculations is reviewed, including growth, dehydrogenation, hydrogenation, oxidation reactions, bias, and recombination of carbon materials that can guide catalyst calculations. Machine learning has attracted increasing interest in recent years, and its combination with the field of catalysts has inspired promising development approaches. Its applications in machine learning potential, catalyst design, performance prediction, structure optimization, and classification have been summarized in detail. This review hopes to shed light and perspective on ML approaches in catalysts.
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Wittkämper H, Maisel S, Moritz M, Grabau M, Görling A, Steinrück HP, Papp C. Surface oxidation-induced restructuring of liquid Pd-Ga SCALMS model catalysts. Phys Chem Chem Phys 2021; 23:16324-16333. [PMID: 34313278 DOI: 10.1039/d1cp02458b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have examined model systems for the recently reported Pd-Ga Supported Catalytically Active Liquid Metal Solutions (SCALMS) catalysts using near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) under oxidizing conditions. Gallium is known to be highly prone to oxidation and in practical applications, handling of the catalyst material in air or the presence of traces of oxygen in the reactor are unavoidable. Therefore, we expect our results to be of high relevance for the application of Ga-based SCALMS catalysts. Pd-Ga alloy samples of 1.3 and 1.8 at% Pd content were exposed to molecular oxygen at different pressures between 3 × 10-7 and 1 mbar and a temperature of 550 K. We observe the formation of wetting Ga2O3 films upon exposure to molecular oxygen. The absolute thicknesses of the oxide films depend on oxygen pressure, with values ranging from ∼12 Å at 10-7 to 10-5 mbar to ∼50 Å at 1 mbar. The formed metal-oxide interface leads to a redistribution of Pd, which accumulates at the boundary between the wetting oxide film and the metal substrate as a response to the oxide film growth. A maximum Pd 3d intensity is observed at an oxide thickness of 5 Å. For thicker films, the Pd 3d signal and the Ga 3d signal ascribed to the metallic substrate decrease in parallel, which is attributed to the oxide layer growing on top of the liquid metal alloy. From this observation, we conclude that no significant amount of Pd is bound in the newly formed oxide film. Density-functional theory (DFT) calculations support the experimental observations.
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Affiliation(s)
- Haiko Wittkämper
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Lehrstuhl für Physikalische Chemie II, Egerlandstr. 3, 91058 Erlangen, Germany.
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