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Abdel‐Mageed AM, Klyushin A, Rezvani A, Knop‐Gericke A, Schlögl R, Behm RJ. Ladungszustand von Au‐Nanopartikeln während der Methanolsynthese aus CO
2
/H
2
an Au/ZnO‐Katalysatoren: Einsichten aus Operando IR‐Spektroskopie und In‐situ XPS‐ und XAS‐Messungen. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201900150] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Ali M. Abdel‐Mageed
- Institut für Oberflächenchemie und KatalyseUniversität Ulm 89069 Ulm Deutschland
- Department of ChemistryFaculty of ScienceCairo University Giza 12613 Ägypten
| | - Alexander Klyushin
- Fritz-Haber-Institut der Max-Planck-Gesellschaft Faradayweg 4–6 14195 Berlin Deutschland
- Max-Planck-Institut für Chemische EnergiewandlungHeterogene Reaktionen Stiftstraße 34–36 45470 Mülheim Deutschland
- Helmholtz-Zentrum Berlin für Materialien und Energie, BESSY II Albert-Einstein-Straße 15 12489 Berlin Deutschland
| | - Azita Rezvani
- Institut für Oberflächenchemie und KatalyseUniversität Ulm 89069 Ulm Deutschland
| | - Axel Knop‐Gericke
- Fritz-Haber-Institut der Max-Planck-Gesellschaft Faradayweg 4–6 14195 Berlin Deutschland
- Max-Planck-Institut für Chemische EnergiewandlungHeterogene Reaktionen Stiftstraße 34–36 45470 Mülheim Deutschland
| | - Robert Schlögl
- Fritz-Haber-Institut der Max-Planck-Gesellschaft Faradayweg 4–6 14195 Berlin Deutschland
- Max-Planck-Institut für Chemische EnergiewandlungHeterogene Reaktionen Stiftstraße 34–36 45470 Mülheim Deutschland
| | - R. Jürgen Behm
- Institut für Oberflächenchemie und KatalyseUniversität Ulm 89069 Ulm Deutschland
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Abdel-Mageed AM, Klyushin A, Rezvani A, Knop-Gericke A, Schlögl R, Behm RJ. Negative Charging of Au Nanoparticles during Methanol Synthesis from CO 2 /H 2 on a Au/ZnO Catalyst: Insights from Operando IR and Near-Ambient-Pressure XPS and XAS Measurements. Angew Chem Int Ed Engl 2019; 58:10325-10329. [PMID: 30980453 DOI: 10.1002/anie.201900150] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Indexed: 11/05/2022]
Abstract
The electronic and structural properties of Au/ZnO under industrial and idealized methanol synthesis conditions have been investigated. This was achieved by kinetic measurements in combination with time-resolved operando infrared (DRIFTS) as well as in situ near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) and X-ray absorption near-edge spectroscopy (XANES) measurements at the O K-edge together with high-resolution electron microscopy. The adsorption of CO during the reaction revealed the presence of negatively charged Au nanoparticles/Au sites during the initial phase of the reaction. Near-ambient-pressure XPS and XANES demonstrate the build-up of O vacancies during the reaction, which goes along with a substantial increase in the rate of methanol formation. The results are discussed in comparison with previous findings for Cu/ZnO and Au/ZnO catalysts.
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Affiliation(s)
- Ali M Abdel-Mageed
- Institute of Surface Chemistry and Catalysis, Ulm University, 89069, Ulm, Germany.,Department of Chemistry, Faculty of Science, Cairo University, Giza, 12613, Egypt
| | - Alexander Klyushin
- Fritz-Haber-Institute, Dept. Inorganic Chemistry, Faradayweg 4-6, 14195, Berlin, Germany.,Max Planck Institute for Chemical Energy Conversion, Heterogeneous Reactions, Stiftstrasse 34-36, 45470, Mülheim, Germany.,Helmholtz-Zentrum Berlin für Materialien und Energie, BESSY II, Albert-Einstein-Strasse 15, 12489, Berlin, Germany
| | - Azita Rezvani
- Institute of Surface Chemistry and Catalysis, Ulm University, 89069, Ulm, Germany
| | - Axel Knop-Gericke
- Fritz-Haber-Institute, Dept. Inorganic Chemistry, Faradayweg 4-6, 14195, Berlin, Germany.,Max Planck Institute for Chemical Energy Conversion, Heterogeneous Reactions, Stiftstrasse 34-36, 45470, Mülheim, Germany
| | - Robert Schlögl
- Fritz-Haber-Institute, Dept. Inorganic Chemistry, Faradayweg 4-6, 14195, Berlin, Germany.,Max Planck Institute for Chemical Energy Conversion, Heterogeneous Reactions, Stiftstrasse 34-36, 45470, Mülheim, Germany
| | - R Jürgen Behm
- Institute of Surface Chemistry and Catalysis, Ulm University, 89069, Ulm, Germany
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Straumal BB, Protasova SG, Mazilkin AA, Goering E, Schütz G, Straumal PB, Baretzky B. Ferromagnetic behaviour of ZnO: the role of grain boundaries. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2016; 7:1936-1947. [PMID: 28144542 PMCID: PMC5238656 DOI: 10.3762/bjnano.7.185] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 11/09/2016] [Indexed: 05/26/2023]
Abstract
The possibility to attain ferromagnetic properties in transparent semiconductor oxides such as ZnO is very promising for future spintronic applications. We demonstrate in this review that ferromagnetism is not an intrinsic property of the ZnO crystalline lattice but is that of ZnO/ZnO grain boundaries. If a ZnO polycrystal contains enough grain boundaries, it can transform into the ferromagnetic state even without doping with "magnetic atoms" such as Mn, Co, Fe or Ni. However, such doping facilitates the appearance of ferromagnetism in ZnO. It increases the saturation magnetisation and decreases the critical amount of grain boundaries needed for FM. A drastic increase of the total solubility of dopants in ZnO with decreasing grain size has been also observed. It is explained by the multilayer grain boundary segregation.
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Affiliation(s)
- Boris Borisovich Straumal
- Karlsruher Institut für Technologie, Institut für Nanotechnologie, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
- Institute of Solid State Physics, Russian Academy of Sciences, Ac. Ossipyan str. 2, 142432 Chernogolovka, Russia
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstrasse 3, 70569 Stuttgart, Germany
- National University for Research and Technology “MISiS”, Leninsky prospect 4, 119991 Moscow, Russia
| | - Svetlana G Protasova
- Institute of Solid State Physics, Russian Academy of Sciences, Ac. Ossipyan str. 2, 142432 Chernogolovka, Russia
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstrasse 3, 70569 Stuttgart, Germany
| | - Andrei A Mazilkin
- Karlsruher Institut für Technologie, Institut für Nanotechnologie, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
- Institute of Solid State Physics, Russian Academy of Sciences, Ac. Ossipyan str. 2, 142432 Chernogolovka, Russia
| | - Eberhard Goering
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstrasse 3, 70569 Stuttgart, Germany
| | - Gisela Schütz
- Max-Planck-Institut für Intelligente Systeme, Heisenbergstrasse 3, 70569 Stuttgart, Germany
| | - Petr B Straumal
- National University for Research and Technology “MISiS”, Leninsky prospect 4, 119991 Moscow, Russia
- Institute of Metallurgy and Materials Science, Russian Academy of Sciences, Leninsky prospect 49, 117991 Moscow, Russia
| | - Brigitte Baretzky
- Karlsruher Institut für Technologie, Institut für Nanotechnologie, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
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Kapilashrami M, Xu J, Rao KV, Belova L, Carlegrim E, Fahlman M. Experimental evidence for ferromagnetism at room temperature in MgO thin films. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:345004. [PMID: 21403248 DOI: 10.1088/0953-8984/22/34/345004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Ferromagnetic ordering at room temperature (RTFM) in MgO thin films deposited by RF magnetron sputtering under various atmospheric conditions and temperatures is reported. A saturation magnetization (M(S)) value as high as 1.58 emu g(-1) is (0.046 μB/unit cell) observed for a 170 nm film deposited at RT under an oxygen pressure of 1.3 × 10(-4) mbar. In contrast, films deposited at elevated temperature (under an identical oxygen pressure), or at higher oxygen pressures, as well as under a nitrogen atmosphere at RT show significantly suppressed magnetization. The ferromagnetic order in the MgO matrix is believed to be defect induced.
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Affiliation(s)
- Mukes Kapilashrami
- Department of Materials Science, Royal Institute of Technology, Stockholm, Sweden.
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Zhou KJ, Tezuka Y, Cui MQ, Zhao J, Liu XC, Chen ZZ, Wu ZY. The mechanism of Al donor defects in (Zn, Co)O:Al: a view from resonant x-ray spectroscopies. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:495502. [PMID: 21836198 DOI: 10.1088/0953-8984/21/49/495502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We studied the effect of Al doping in Zn(0.94)Co(0.05)Al(0.01)O nano-powders from the electronic structure point of view by applying x-ray absorption spectroscopy and resonant inelastic x-ray scattering at the oxygen K- and Co L-edges. The intensity of the pre-edge structure of the O-K XAS spectra is enhanced following the introduction of the Al defect. Multiple scattering calculations demonstrate it can be accounted for by the gain of the hybridization strength between O 2p and Al 3p (and/or Co 3d) states. The consensus on the hybridization strength is reached by combining Co-L XAS and RIXS investigations and multiplet calculations. It reveals different spatial substitutions of Al doping can alter the number of shared oxygen atoms between the Co and Al tetrahedrons. These shared ligands are responsible for the Al 3p and Co 3d state hybridization strength as well as the ferromagnetism of the ground state. The magnetic difference is better understood to be governed by various shared oxygen atoms rather than the distance between the Al defect and Co impurities.
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Affiliation(s)
- K J Zhou
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Beijing 100049, People's Republic of China
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Bondino F, Garg KB, Magnano E, Carleschi E, Heinonen M, Singhal RK, Gaur SK, Parmigiani F. Electronic structure of Mn-doped ZnO by x-ray emission and absorption spectroscopy. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2008; 20:275205. [PMID: 21694367 DOI: 10.1088/0953-8984/20/27/275205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We report an investigation of Mn-doped ZnO pellets with diluted Mn concentration by soft-x-ray emission and absorption spectroscopy. We have compared the electronic structure of two samples with different Mn concentration and different magnetic properties at room temperature: ferromagnetism in one case (Zn(0.98)Mn(0.02)O) and no magnetic order in the other (Zn(0.96)Mn(0.04)O). The results show that most of the Mn ions of the ferromagnetic sample are in the divalent state. For the nonmagnetic sample, a larger contribution of higher oxidation Mn states is present, which can be correlated to the suppressed ferromagnetism. The presence of oxygen atoms bonded to Mn ions and hybridized Mn 3d-O 2p states has been detected in both compounds. The partial density of states in the valence band has been measured with x-ray emission spectroscopy and the Mn 3d states have been found inside the bandgap of ZnO.
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Affiliation(s)
- F Bondino
- Laboratorio Nazionale TASC INFM-CNR, Basovizza-Trieste, Italy
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