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Wittstock G, Bäumer M, Dononelli W, Klüner T, Lührs L, Mahr C, Moskaleva LV, Oezaslan M, Risse T, Rosenauer A, Staubitz A, Weissmüller J, Wittstock A. Nanoporous Gold: From Structure Evolution to Functional Properties in Catalysis and Electrochemistry. Chem Rev 2023; 123:6716-6792. [PMID: 37133401 DOI: 10.1021/acs.chemrev.2c00751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Nanoporous gold (NPG) is characterized by a bicontinuous network of nanometer-sized metallic struts and interconnected pores formed spontaneously by oxidative dissolution of the less noble element from gold alloys. The resulting material exhibits decent catalytic activity for low-temperature, aerobic total as well as partial oxidation reactions, the oxidative coupling of methanol to methyl formate being the prototypical example. This review not only provides a critical discussion of ways to tune the morphology and composition of this material and its implication for catalysis and electrocatalysis, but will also exemplarily review the current mechanistic understanding of the partial oxidation of methanol using information from quantum chemical studies, model studies on single-crystal surfaces, gas phase catalysis, aerobic liquid phase oxidation, and electrocatalysis. In this respect, a particular focus will be on mechanistic aspects not well understood, yet. Apart from the mechanistic aspects of catalysis, best practice examples with respect to material preparation and characterization will be discussed. These can improve the reproducibility of the materials property such as the catalytic activity and selectivity as well as the scope of reactions being identified as the main challenges for a broader application of NPG in target-oriented organic synthesis.
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Affiliation(s)
- Gunther Wittstock
- Carl von Ossietzky University of Oldenburg, School of Mathematics and Science, Institute of Chemistry, D-26111 Oldenburg, Germany
| | - Marcus Bäumer
- University of Bremen, Institute for Applied and Physical Chemistry, 28359 Bremen, Germany
- University of Bremen, MAPEX Center for Materials and Processes, 28359 Bremen, Germany
| | - Wilke Dononelli
- University of Bremen, MAPEX Center for Materials and Processes, 28359 Bremen, Germany
- University of Bremen, Bremen Center for Computational Materials Science, Hybrid Materials Interfaces Group, Am Fallturm 1, Bremen 28359, Germany
| | - Thorsten Klüner
- Carl von Ossietzky University of Oldenburg, School of Mathematics and Science, Institute of Chemistry, D-26111 Oldenburg, Germany
| | - Lukas Lührs
- Hamburg University of Technology, Institute of Materials Physics and Technology, 21703 Hamburg, Germany
| | - Christoph Mahr
- University of Bremen, MAPEX Center for Materials and Processes, 28359 Bremen, Germany
- University of Bremen, Institute of Solid State Physics, Otto Hahn Allee 1, 28359 Bremen, Germany
| | - Lyudmila V Moskaleva
- University of the Free State, Department of Chemistry, P.O. Box 339, Bloemfontein 9300, South Africa
| | - Mehtap Oezaslan
- Technical University of Braunschweig Institute of Technical Chemistry, Technical Electrocatalysis Laboratory, Franz-Liszt-Strasse 35a, 38106 Braunschweig, Germany
| | - Thomas Risse
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, Arnimallee 22, 14195 Berlin, Germany
| | - Andreas Rosenauer
- University of Bremen, MAPEX Center for Materials and Processes, 28359 Bremen, Germany
- University of Bremen, Institute of Solid State Physics, Otto Hahn Allee 1, 28359 Bremen, Germany
| | - Anne Staubitz
- University of Bremen, MAPEX Center for Materials and Processes, 28359 Bremen, Germany
- University of Bremen, Institute for Organic and Analytical Chemistry, Leobener Strasse 7, D-28359 Bremen, Germany
| | - Jörg Weissmüller
- Hamburg University of Technology, Institute of Materials Physics and Technology, 21703 Hamburg, Germany
- Helmholtz-Zentrum Hereon, Institute of Materials Mechanics, 21502 Geesthacht, Germany
| | - Arne Wittstock
- University of Bremen, MAPEX Center for Materials and Processes, 28359 Bremen, Germany
- University of Bremen, Institute for Organic and Analytical Chemistry, Leobener Strasse 7, D-28359 Bremen, Germany
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2
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Kwon H, Barad HN, Silva Olaya AR, Alarcón-Correa M, Hahn K, Richter G, Wittstock G, Fischer P. Dry Synthesis of Pure and Ultrathin Nanoporous Metallic Films. ACS APPLIED MATERIALS & INTERFACES 2023; 15:5620-5627. [PMID: 36690332 PMCID: PMC9906609 DOI: 10.1021/acsami.2c19584] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 12/27/2022] [Indexed: 05/27/2023]
Abstract
Nanoporous metals possess unique properties attributed to their high surface area and interconnected nanoscale ligaments. They are mostly fabricated by wet synthetic methods that are not universal to various metals and not free from impurities due to solution-based etching processes. Here, we demonstrate that the plasma treatment of metal nanoparticles formed by physical vapor deposition is a general route to form such films with many metals including the non-noble ones. The resultant nanoporous metallic films are free of impurities and possess highly curved ligaments and nanopores. The metal films are ultrathin, yet remarkably robust and very well connected, and thus are highly promising for various applications such as transparent conducting electrodes.
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Affiliation(s)
- Hyunah Kwon
- Institute
for Molecular Systems Engineering and Advanced Materials, Heidelberg University, INF 225, 69120 Heidelberg, Germany
- Max
Planck Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - Hannah-Noa Barad
- Department
of Chemistry, Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002 Israel
| | - Alex Ricardo Silva Olaya
- School
of Mathematics and Science, Department of Chemistry, Carl von Ossietzky University of Oldenburg, 26111 Oldenburg, Germany
| | - Mariana Alarcón-Correa
- Institute
for Molecular Systems Engineering and Advanced Materials, Heidelberg University, INF 225, 69120 Heidelberg, Germany
- Max
Planck Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - Kersten Hahn
- Max
Planck
Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany
| | - Gunther Richter
- Max
Planck Institute for Intelligent Systems, Heisenbergstrasse 3, 70569 Stuttgart, Germany
| | - Gunther Wittstock
- School
of Mathematics and Science, Department of Chemistry, Carl von Ossietzky University of Oldenburg, 26111 Oldenburg, Germany
| | - Peer Fischer
- Institute
for Molecular Systems Engineering and Advanced Materials, Heidelberg University, INF 225, 69120 Heidelberg, Germany
- Max
Planck Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany
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3
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Wild S, Mahr C, Rosenauer A, Risse T, Vasenkov S, Bäumer M. New Perspectives for Evaluating the Mass Transport in Porous Catalysts and Unfolding Macro- and Microkinetics. Catal Letters 2022; 153:3405-3422. [PMID: 37799191 PMCID: PMC10547662 DOI: 10.1007/s10562-022-04218-6] [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: 10/27/2022] [Accepted: 11/11/2022] [Indexed: 12/13/2022]
Abstract
In this article we shed light on newly emerging perspectives to characterize and understand the interplay of diffusive mass transport and surface catalytic processes in pores of gas phase metal catalysts. As a case study, nanoporous gold, as an interesting example exhibiting a well-defined pore structure and a high activity for total and partial oxidation reactions is considered. PFG NMR (pulsed field gradient nuclear magnetic resonance) measurements allowed here for a quantitative evaluation of gas diffusivities within the material. STEM (scanning transmission electron microscopy) tomography furthermore provided additional insight into the structural details of the pore system, helping to judge which of its features are most decisive for slowing down mass transport. Based on the quantitative knowledge about the diffusion coefficients inside a porous catalyst, it becomes possible to disentangle mass transport contributions form the measured reaction kinetics and to determine the kinetic rate constant of the underlying catalytic surface reaction. In addition, predictions can be made for an improved effectiveness of the catalyst, i.e., optimized conversion rates. This approach will be discussed at the example of low-temperature CO oxidation, efficiently catalysed by npAu at 30 °C. The case study shall reveal that novel porous materials exhibiting well-defined micro- and mesoscopic features and sufficient catalytic activity, in combination with modern techniques to evaluate diffusive transport, offer interesting new opportunities for an integral understanding of catalytic processes. Graphical Abstract
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Affiliation(s)
- Stefan Wild
- Institute for Applied and Physical Chemistry, University of Bremen, 28359 Bremen, Germany
- MAPEX Center of Materials and Processes, University of Bremen, 28359 Bremen, Germany
| | - Christoph Mahr
- MAPEX Center of Materials and Processes, University of Bremen, 28359 Bremen, Germany
- Institute of Solid State Physics, University of Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany
| | - Andreas Rosenauer
- MAPEX Center of Materials and Processes, University of Bremen, 28359 Bremen, Germany
- Institute of Solid State Physics, University of Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany
| | - Thomas Risse
- Institute of Chemistry and Biochemistry, Free University Berlin, 14195 Berlin, Germany
| | - Sergey Vasenkov
- Department of Chemical Engineering, University of Florida, Gainesville, FL 32611 USA
| | - Marcus Bäumer
- Institute for Applied and Physical Chemistry, University of Bremen, 28359 Bremen, Germany
- MAPEX Center of Materials and Processes, University of Bremen, 28359 Bremen, Germany
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4
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Silva Olaya AR, Kühling F, Mahr C, Zandersons B, Rosenauer A, Weissmüller J, Wittstock G. Promoting Effect of the Residual Silver on the Electrocatalytic Oxidation of Methanol and Its Intermediates on Nanoporous Gold. ACS Catal 2022. [DOI: 10.1021/acscatal.1c05160] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Alex Ricardo Silva Olaya
- Carl von Ossietzky University of Oldenburg, School of Mathematics and Science, Institute of Chemistry, 26111 Oldenburg, Germany
| | - Franziska Kühling
- Carl von Ossietzky University of Oldenburg, School of Mathematics and Science, Institute of Chemistry, 26111 Oldenburg, Germany
| | - Christoph Mahr
- Institute for Solid State Physics, University of Bremen, 28359 Bremen, Germany
- MAPEX Center for Materials and Processes, University of Bremen, 28359 Bremen, Germany
| | - Birthe Zandersons
- Institute of Materials Physics and Technology, Hamburg University of Technology, 21073 Hamburg, Germany
| | - Andreas Rosenauer
- Institute for Solid State Physics, University of Bremen, 28359 Bremen, Germany
- MAPEX Center for Materials and Processes, University of Bremen, 28359 Bremen, Germany
| | - Jörg Weissmüller
- Institute of Materials Physics and Technology, Hamburg University of Technology, 21073 Hamburg, Germany
- Helmholtz-Zentrum Hereon, Institute of Materials Mechanics, 21502 Geesthacht, Germany
| | - Gunther Wittstock
- Carl von Ossietzky University of Oldenburg, School of Mathematics and Science, Institute of Chemistry, 26111 Oldenburg, Germany
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5
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Silva Olaya AR, Zandersons B, Wittstock G. Effect of the residual silver and adsorbed lead anions towards the electrocatalytic methanol oxidation on nanoporous gold in alkaline media. Electrochim Acta 2021. [DOI: 10.1016/j.electacta.2021.138348] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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6
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Kumar A, Gonçalves JM, Furtado VL, Araki K, Angnes L, Bouvet M, Bertotti M, Meunier‐Prest R. Mass Transport in Nanoporous Gold and Correlation with Surface Pores for EC
1
Mechanism: Case of Ascorbic Acid. ChemElectroChem 2021. [DOI: 10.1002/celc.202100440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Abhishek Kumar
- Institut de Chimie Moléculaire de l'Université de Bourgogne UMR CNRS 6302 Université Bourgogne Franche-Comté 9 Avenue Alain Savary Dijon Cedex 21078 France
- Department of Fundamental Chemistry Institute of Chemistry University of São Paulo Av. Prof. Lineu Prestes, 748 05508-000 São Paulo, SP Brazil
| | - Josue M. Gonçalves
- Department of Fundamental Chemistry Institute of Chemistry University of São Paulo Av. Prof. Lineu Prestes, 748 05508-000 São Paulo, SP Brazil
| | - Vinicius L. Furtado
- Department of Fundamental Chemistry Institute of Chemistry University of São Paulo Av. Prof. Lineu Prestes, 748 05508-000 São Paulo, SP Brazil
| | - Koiti Araki
- Department of Fundamental Chemistry Institute of Chemistry University of São Paulo Av. Prof. Lineu Prestes, 748 05508-000 São Paulo, SP Brazil
| | - Lucio Angnes
- Department of Fundamental Chemistry Institute of Chemistry University of São Paulo Av. Prof. Lineu Prestes, 748 05508-000 São Paulo, SP Brazil
| | - Marcel Bouvet
- Institut de Chimie Moléculaire de l'Université de Bourgogne UMR CNRS 6302 Université Bourgogne Franche-Comté 9 Avenue Alain Savary Dijon Cedex 21078 France
| | - Mauro Bertotti
- Department of Fundamental Chemistry Institute of Chemistry University of São Paulo Av. Prof. Lineu Prestes, 748 05508-000 São Paulo, SP Brazil
| | - Rita Meunier‐Prest
- Institut de Chimie Moléculaire de l'Université de Bourgogne UMR CNRS 6302 Université Bourgogne Franche-Comté 9 Avenue Alain Savary Dijon Cedex 21078 France
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7
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Silva Olaya AR, Zandersons B, Wittstock G. Restructuring of Nanoporous Gold Surfaces During Electrochemical Cycling in Acidic and Alkaline Media. ChemElectroChem 2020. [DOI: 10.1002/celc.202000923] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
| | - Birthe Zandersons
- Institute of Materials Physics and Technology Hamburg University of Technology 21073 Hamburg Germany
| | - Gunther Wittstock
- Department of Chemistry Carl von Ossietzky University of Oldenburg 26111 Oldenburg Germany
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8
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Gao Y, Ding Y. Nanoporous Metals for Heterogeneous Catalysis: Following the Success of Raney Nickel. Chemistry 2020; 26:8845-8856. [DOI: 10.1002/chem.202000471] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Indexed: 11/10/2022]
Affiliation(s)
- Yanxiu Gao
- Tianjin Key Laboratory of Advanced Functional Porous MaterialsInstitute for New Energy Materials and Low-Carbon TechnologiesSchool of Materials Science and EngineeringTianjin University of Technology Tianjin 300384 P. R. China
| | - Yi Ding
- Tianjin Key Laboratory of Advanced Functional Porous MaterialsInstitute for New Energy Materials and Low-Carbon TechnologiesSchool of Materials Science and EngineeringTianjin University of Technology Tianjin 300384 P. R. China
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9
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Steinebrunner D, Schnurpfeil G, Kohröde M, Epp A, Klangnog K, Tapia Burgos JA, Wichmann A, Wöhrle D, Wittstock A. Impact of photosensitizer orientation on the distance dependent photocatalytic activity in zinc phthalocyanine–nanoporous gold hybrid systems. RSC Adv 2020; 10:23203-23211. [PMID: 35520339 PMCID: PMC9054629 DOI: 10.1039/d0ra03891a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 06/11/2020] [Indexed: 12/17/2022] Open
Abstract
The distance dependency of the photocatalytic activity in zinc phthalocyanine–nanoporous gold hybrid systems was investigated revealing the importance of photosensitizer orientation in novel hybrid-based photocatalysts.
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Affiliation(s)
- David Steinebrunner
- Institute of Applied and Physical Chemistry and Center for Environmental Research and Sustainable Technology
- University Bremen
- 28359 Bremen
- Germany
- MAPEX Center for Materials and Processes
| | - Günter Schnurpfeil
- Organic and Macromolecular Chemistry
- University Bremen
- 28359 Bremen
- Germany
| | - Mathis Kohröde
- Institute of Applied and Physical Chemistry and Center for Environmental Research and Sustainable Technology
- University Bremen
- 28359 Bremen
- Germany
| | - Alexander Epp
- Institute of Applied and Physical Chemistry and Center for Environmental Research and Sustainable Technology
- University Bremen
- 28359 Bremen
- Germany
| | | | - Jorge Adrian Tapia Burgos
- Institute of Applied and Physical Chemistry and Center for Environmental Research and Sustainable Technology
- University Bremen
- 28359 Bremen
- Germany
- MAPEX Center for Materials and Processes
| | - Andre Wichmann
- Institute of Applied and Physical Chemistry and Center for Environmental Research and Sustainable Technology
- University Bremen
- 28359 Bremen
- Germany
| | - Dieter Wöhrle
- Organic and Macromolecular Chemistry
- University Bremen
- 28359 Bremen
- Germany
| | - Arne Wittstock
- Institute of Applied and Physical Chemistry and Center for Environmental Research and Sustainable Technology
- University Bremen
- 28359 Bremen
- Germany
- MAPEX Center for Materials and Processes
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10
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Gold Nanoparticles for Oxidation Reactions: Critical Role of Supports and Au Particle Size. TOP ORGANOMETAL CHEM 2020. [DOI: 10.1007/3418_2020_42] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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11
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Ishida T, Murayama T, Taketoshi A, Haruta M. Importance of Size and Contact Structure of Gold Nanoparticles for the Genesis of Unique Catalytic Processes. Chem Rev 2019; 120:464-525. [DOI: 10.1021/acs.chemrev.9b00551] [Citation(s) in RCA: 249] [Impact Index Per Article: 49.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Tamao Ishida
- Department of Applied Chemistry for Environment, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan
- Research Center for Gold Chemistry, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan
| | - Toru Murayama
- Department of Applied Chemistry for Environment, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan
- Research Center for Gold Chemistry, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan
| | - Ayako Taketoshi
- Department of Applied Chemistry for Environment, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan
- Research Center for Gold Chemistry, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan
| | - Masatake Haruta
- Research Center for Gold Chemistry, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan
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12
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Fam Y, Sheppard TL, Becher J, Scherhaufer D, Lambach H, Kulkarni S, Keller TF, Wittstock A, Wittwer F, Seyrich M, Brueckner D, Kahnt M, Yang X, Schropp A, Stierle A, Schroer CG, Grunwaldt JD. A versatile nanoreactor for complementary in situ X-ray and electron microscopy studies in catalysis and materials science. JOURNAL OF SYNCHROTRON RADIATION 2019; 26:1769-1781. [PMID: 31490169 PMCID: PMC6732905 DOI: 10.1107/s160057751900660x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 05/08/2019] [Indexed: 05/04/2023]
Abstract
Two in situ `nanoreactors' for high-resolution imaging of catalysts have been designed and applied at the hard X-ray nanoprobe endstation at beamline P06 of the PETRA III synchrotron radiation source. The reactors house samples supported on commercial MEMS chips, and were applied for complementary hard X-ray ptychography (23 nm spatial resolution) and transmission electron microscopy, with additional X-ray fluorescence measurements. The reactors allow pressures of 100 kPa and temperatures of up to 1573 K, offering a wide range of conditions relevant for catalysis. Ptychographic tomography was demonstrated at limited tilting angles of at least ±35° within the reactors and ±65° on the naked sample holders. Two case studies were selected to demonstrate the functionality of the reactors: (i) annealing of hierarchical nanoporous gold up to 923 K under inert He environment and (ii) acquisition of a ptychographic projection series at ±35° of a hierarchically structured macroporous zeolite sample under ambient conditions. The reactors are shown to be a flexible and modular platform for in situ studies in catalysis and materials science which may be adapted for a range of sample and experiment types, opening new characterization pathways in correlative multimodal in situ analysis of functional materials at work. The cells will presently be made available for all interested users of beamline P06 at PETRA III.
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Affiliation(s)
- Yakub Fam
- Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology, Engesserstraße 20, Karlsruhe, Baden Württemberg 76131, Germany
| | - Thomas L. Sheppard
- Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology, Engesserstraße 20, Karlsruhe, Baden Württemberg 76131, Germany
- Institute of Catalysis Research and Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz Platz 1, Eggenstein-Leopoldshafen, Baden Württemberg 76344, Germany
| | - Johannes Becher
- Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology, Engesserstraße 20, Karlsruhe, Baden Württemberg 76131, Germany
| | - Dennis Scherhaufer
- Institute for Micro Process Engineering, Karlsruhe Institute of Technology, Hermann-von-Helmholtz Platz 1, Eggenstein-Leopoldshafen, Baden Württemberg 76344, Germany
| | - Heinz Lambach
- Institute for Micro Process Engineering, Karlsruhe Institute of Technology, Hermann-von-Helmholtz Platz 1, Eggenstein-Leopoldshafen, Baden Württemberg 76344, Germany
| | | | - Thomas F. Keller
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, Hamburg 22607, Germany
- Department Physik, Universität Hamburg, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Arne Wittstock
- Institute of Applied and Physical Chemistry, University of Bremen, Bremen 28359, Germany
| | - Felix Wittwer
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, Hamburg 22607, Germany
- Department Physik, Universität Hamburg, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Martin Seyrich
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, Hamburg 22607, Germany
- Department Physik, Universität Hamburg, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Dennis Brueckner
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, Hamburg 22607, Germany
- Department Physik, Universität Hamburg, Luruper Chaussee 149, Hamburg 22761, Germany
- Faculty of Chemistry and Biochemistry, Ruhr-University Bochum, Universitätsstraße 150, Bochum 44801, Germany
| | - Maik Kahnt
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, Hamburg 22607, Germany
- Department Physik, Universität Hamburg, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Xiaogang Yang
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, Hamburg 22607, Germany
| | - Andreas Schropp
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, Hamburg 22607, Germany
| | - Andreas Stierle
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, Hamburg 22607, Germany
- Department Physik, Universität Hamburg, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Christian G. Schroer
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, Hamburg 22607, Germany
- Department Physik, Universität Hamburg, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Jan-Dierk Grunwaldt
- Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology, Engesserstraße 20, Karlsruhe, Baden Württemberg 76131, Germany
- Institute of Catalysis Research and Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz Platz 1, Eggenstein-Leopoldshafen, Baden Württemberg 76344, Germany
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Demirci C, Marras S, Prato M, Pasquale L, Manna L, Colombo M. Design of catalytically active porous gold structures from a bottom-up method: The role of metal traces in CO oxidation and oxidative coupling of methanol. J Catal 2019. [DOI: 10.1016/j.jcat.2019.06.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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14
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Synergistic Effect in Zinc Phthalocyanine—Nanoporous Gold Hybrid Materials for Enhanced Photocatalytic Oxidations. Catalysts 2019. [DOI: 10.3390/catal9060555] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Nanoporous gold (npAu) supports were prepared as disks and powders by corrosion of Au-Ag alloys. The npAu materials have pore sizes in the range of 40 nm as shown by scanning electron microscopy (SEM). The surface was modified by a self-assembled monolayer (SAM) with an azidohexylthioate and then functionalized by a zinc (II) phthalocyanine (ZnPc) derivative using “click chemistry”. By atomic absorption spectroscopy (AAS) and inductively coupled plasma mass spectrometry (ICP-MS) the content of zinc was determined and the amount of immobilized ZnPc on npAu was calculated. Energy-dispersive X-ray (EDX) spectroscopy gave information about the spatial distribution of the ZnPc throughout the whole porous structure. NpAu and ZnPc are both absorbing light in the visible region, therefore, the heterogeneous hybrid systems were studied as photocatalysts for photooxidations using molecular oxygen. By irradiation of the hybrid system, singlet oxygen is formed, which was quantified using the photooxidation of 1,3-diphenylisobenzofuran (DPBF) as a selective singlet oxygen quencher. The illuminated surface area of the npAu-ZnPc hybrid system and the coverage of the ZnPc were optimized. The synergistic effect between the plasmon resonance of npAu and the photosensitizer ZnPc was shown by selective irradiation and excitation of only the phthalocyanine, the plasmon resonance of the npAu support and both absorption bands simultaneously, resulting in an enhanced photooxidation activity by nearly an order of magnitude.
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15
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Aerobic Methanol Oxidation over Unsupported Nanoporous Gold: The Influence of an Added Base. Catalysts 2019. [DOI: 10.3390/catal9050416] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
We studied the aerobic oxidation of methanol over nanoporous gold catalysts under neutral and alkaline conditions. We find that under neutral conditions the catalyst has an activation period of about 10 h while upon addition of a base the catalyst becomes active right away. After this activation period, however, the activity of the catalyst is in both cases similar. Moreover, the selectivity was not affected by the base. We tested different bases and found the largest effect when adding OH−. The cation, however, does not play a role. We conclude that it is OH−, which is impacting the reaction and propose a mechanism for the suppression of the activation period. While the catalytic cycle, i.e., the reaction of methanol on the catalyst surface seems unaffected, the transient adsorption of OH− onto the surface can facilitate the activation of molecular oxygen by donating electrons to the surface. Due to the intermediate formation of oxidic Ag species, an effective segregation of surface-near Ag can be induced, which increases the abundance of Ag being essential for the activation of oxygen at the surface. In this way, a more efficient pathway for the generation of active oxygen is opened, allowing the reaction to set in faster.
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