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Jo SE, Jeon S, Kim HJ, Yang BC, Ju K, Gür TM, Jung W, An J. Simultaneous Performance and Stability Enhancement in Intermediate Temperature Solid Oxide Fuel Cells by Powder-Atomic Layer Deposited LSCF@ZrO 2 Cathodes. SMALL METHODS 2023:e2300790. [PMID: 37749956 DOI: 10.1002/smtd.202300790] [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] [Revised: 08/26/2023] [Indexed: 09/27/2023]
Abstract
Employing porous structures is essential in high-performance electrochemical energy devices. However, obtaining uniform functional coatings on high-tortuosity structures can be challenging, even with specialized processes such as atomic layer deposition (ALD). Herein, a novel method for achieving a porous composite electrode for solid oxide fuel cells by coating La0.6 Sr0.4 Co0.2 Fe0.8 O3 -δ (LSCF) powders with ZrO2 using a powder ALD process is presented. Unlike conventional ALD, powder ALD can be used to fabricate extremely uniform coatings on porous electrodes with a thickness of tens of micrometers. The powder ALD ZrO2 coating is found to effectively suppress chemical degradation of the LSCF electrodes. The cell with the powder ALD coated cathode shows a 2.2 times higher maximum power density and 60% lower thermal degradation in activation resistance than the bare LSCF cathode cell at 700-750 °C. The result demonstrated in this study is expected to have significant implications for high-performance and durable electrodes in energy conversion/storage devices.
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Affiliation(s)
- Sung Eun Jo
- Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-ro, Pohang, 37673, South Korea
| | - SungHyun Jeon
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, South Korea
| | - Hyong June Kim
- Department of Nano-Bio Engineering, Research Institute of Energy and Environment, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul, 01811, South Korea
| | - Byung Chan Yang
- Energy Materials Research Center Clean Energy Research Division, Korea Institute of Science and Technology (KIST), 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul, 02792, Republic of Korea
| | - Kyoungjae Ju
- Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-ro, Pohang, 37673, South Korea
| | - Turgut M Gür
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - WooChul Jung
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, South Korea
| | - Jihwan An
- Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-ro, Pohang, 37673, South Korea
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2
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Li H, Kim HJ, Garcia T, Park G, Ding Y, Liu M, An J, Lee MH. Ultralow Loading of Ru as a Bifunctional Catalyst for the Oxygen Electrode of Solid Oxide Cells. ACS Catal 2023; 13:11172-11181. [PMID: 37614520 PMCID: PMC10442917 DOI: 10.1021/acscatal.3c02544] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Revised: 07/28/2023] [Indexed: 08/25/2023]
Abstract
The oxygen evolution reaction (OER) is a significant contributor to the cell overpotential in solid oxide electrolyzer cells (SOECs). Although noble metals such as Ru and Ir have been utilized as OER catalysts, their widespread application in SOECs is hindered by their high cost and limited availability. In this study, we present a highly effective approach to enhance air electrode performance and durability by depositing an ultrathin layer of metallic Ru, as thin as ∼7.5 Å, onto (La0.6Sr0.4)0.95Co0.2Fe0.8O3-δ (LSCF) using plasma-enhanced atomic layer deposition (PEALD). Our study suggests that the emergence of a perovskite, SrRuO3, resulting from the reaction between PEALD-based Ru and surface-segregated Sr species, plays a crucial role in suppressing Sr segregation and maintaining favorable oxygen desorption kinetics, which ultimately improves the OER durability. Further, the PEALD Ru coating on LSCF also reduces the resistance to the oxygen reduction reaction (ORR), highlighting the bifunctional electrocatalytic activities for reversible fuel cells. When the LSCF electrode of a test cell is decorated with ∼7.5 Å of the Ru overcoat, a current density of 656 mA cm-2 at 1.3 V in electrolysis mode and a peak power density of 803 mW cm-2 in fuel cell mode are demonstrated at 700 °C, corresponding to an enhancement of 49.1 and 31.9%, respectively, compared to the pristine cell.
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Affiliation(s)
- Haoyu Li
- Department
of Mechanical Engineering, University of
California, Merced, California 95343, United States
| | - Hyong June Kim
- Department
of Manufacturing System and Design Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea
| | - ThomasJae Garcia
- Department
of Mechanical Engineering, University of
California, Merced, California 95343, United States
| | - Geonwoo Park
- Department
of Manufacturing System and Design Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea
| | - Yong Ding
- School
of Materials Science and Engineering, Georgia
Institute of Technology, Atlanta, Georgia 30332-0245, United States
| | - Meilin Liu
- School
of Materials Science and Engineering, Georgia
Institute of Technology, Atlanta, Georgia 30332-0245, United States
| | - Jihwan An
- Department
of Mechanical Engineering, Pohang University
of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
| | - Min Hwan Lee
- Department
of Mechanical Engineering, University of
California, Merced, California 95343, United States
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3
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Morales M, Laguna-Bercero MÁ, Jiménez-Piqué E. Hydrogen-Rich Gas Production by Steam Reforming and Oxidative Steam Reforming of Methanol over La 0.6Sr 0.4CoO 3-δ: Effects of Preparation, Operation Conditions, and Redox Cycles. ACS APPLIED ENERGY MATERIALS 2023; 6:7887-7898. [PMID: 37592929 PMCID: PMC10431340 DOI: 10.1021/acsaem.3c00778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 07/10/2023] [Indexed: 08/19/2023]
Abstract
La0.6Sr0.4CoO3-δ (LSC) perovskite, as a potential catalyst precursor for hydrogen (H2)-rich production by steam reforming of methanol (SRM) and oxidative steam reforming of methanol (OSRM), was investigated. For this purpose, LSC was synthesized by the citrate sol-gel method and characterized by complementary analytical techniques. The catalytic activity was studied for the as-prepared and prereduced LSC and compared with the undoped LaCoO3-δ (LCO) at several feed gas compositions. Furthermore, the degradation and regeneration of LSC under repeated redox cycles were studied. The results evidenced that the increase in the water/methanol ratio under SRM, and the O2 addition under OSRM, increased the CO2 formation and decreased both the H2 selectivity and catalyst deactivation caused by carbon deposition. Methanol conversion of the prereduced LSC was significantly enhanced at a lower temperature than that of as-prepared LSC and undoped LCO. This was attributed to the performance of metallic cobalt nanoparticles highly dispersed under reducing atmospheres. The reoxidation program in repetitive redox cycles played a crucial role in the regeneration of catalysts, which could be regenerated to the initial perovskite structure under a specific thermal treatment, minimizing the degradation of the catalytic activity and surface.
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Affiliation(s)
- Miguel Morales
- CIEFMA—Department
of Materials Science and Engineering, EEBE—Campus Diagonal
Besòs, Universitat Politècnica
de Catalunya—BarcelonaTech, C/Eduard Maristany 16, 08019 Barcelona, Spain
- Barcelona
Research Center in Multiscale Science and Engineering, Universitat Politècnica de Catalunya—BarcelonaTech, C/Eduard Maristany 16, 08019 Barcelona, Spain
| | - Miguel Ángel Laguna-Bercero
- Instituto
de Nanociencia y Materiales de Aragón, INMA, CSIC, Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain
| | - Emilio Jiménez-Piqué
- CIEFMA—Department
of Materials Science and Engineering, EEBE—Campus Diagonal
Besòs, Universitat Politècnica
de Catalunya—BarcelonaTech, C/Eduard Maristany 16, 08019 Barcelona, Spain
- Barcelona
Research Center in Multiscale Science and Engineering, Universitat Politècnica de Catalunya—BarcelonaTech, C/Eduard Maristany 16, 08019 Barcelona, Spain
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4
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Siebenhofer M, Riedl C, Nenning A, Artner W, Rameshan C, Opitz AK, Fleig J, Kubicek M. Improving and degrading the oxygen exchange kinetics of La 0.6Sr 0.4CoO 3-δ by Sr decoration. JOURNAL OF MATERIALS CHEMISTRY. A 2023; 11:12827-12836. [PMID: 37346740 PMCID: PMC10281333 DOI: 10.1039/d2ta09362f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 02/11/2023] [Indexed: 06/23/2023]
Abstract
Minimizing the overpotential at the air electrode of solid oxide fuel cells (SOFC) is one of the key challenges regarding a broad applicability of this technology. Next to novel materials and geometry optimization, surface modification is a promising and flexible method to alter the oxygen exchange kinetics at SOFC cathode surfaces. Despite extensive research, the mechanism behind the effect of surface decorations is still under debate. Moreover, for Sr decoration, previous studies yielded conflicting results, reporting either a beneficial or a detrimental impact on the oxygen exchange kinetics. In this contribution, in situ impedance spectroscopy during pulsed laser deposition was used to investigate the effect of Sr containing decorations under different deposition conditions. Depending on deposition temperature and interactions with the gas phase, opposing effects of Sr decoration were found. In combination with near-ambient pressure X-ray photoelectron spectroscopy and non-ambient X-ray diffractometry, it was possible to trace this phenomenon back to different chemical environments of the surface Sr. At high temperatures, Sr is deposited as SrO, which can have a beneficial effect on the oxygen exchange kinetics. At low temperatures, SrCO3 adsorbates are formed from trace amounts of CO2 in the measurement atmosphere, causing a decrease of the oxygen exchange rate. These results are in excellent agreement with the concept of surface acidity as a descriptor for the effect of surface decorations, providing further insight into the oxygen exchange kinetics on SOFC cathode surfaces and its degradation. In addition, this study shows that Sr segregation itself initially does not lead to performance degradation but that segregated SrO readily reacts with acidic compounds, reducing the catalytic capability of mixed conducting oxides.
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Affiliation(s)
- Matthäus Siebenhofer
- Institute of Chemical Technologies and Analytics, TU Wien Vienna Austria
- Centre for Electrochemistry and Surface Technology, CEST Wr. Neustadt Austria
| | - Christoph Riedl
- Institute of Chemical Technologies and Analytics, TU Wien Vienna Austria
| | - Andreas Nenning
- Institute of Chemical Technologies and Analytics, TU Wien Vienna Austria
| | | | | | | | - Jürgen Fleig
- Institute of Chemical Technologies and Analytics, TU Wien Vienna Austria
| | - Markus Kubicek
- Institute of Chemical Technologies and Analytics, TU Wien Vienna Austria
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5
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Haug L, Griesser C, Thurner CW, Winkler D, Moser T, Thaler M, Bartl P, Rainer M, Portenkirchner E, Schumacher D, Dierschke K, Köpfle N, Penner S, Beyer MK, Loerting T, Kunze-Liebhäuser J, Klötzer B. A laboratory-based multifunctional near ambient pressure X-ray photoelectron spectroscopy system for electrochemical, catalytic, and cryogenic studies. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:065104. [PMID: 37862508 DOI: 10.1063/5.0151755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 05/27/2023] [Indexed: 10/22/2023]
Abstract
A versatile multifunctional laboratory-based near ambient pressure x-ray photoelectron spectroscopy (XPS) instrument is presented. The entire device is highly customized regarding geometry, exchangeable manipulators and sample stages for liquid- and solid-state electrochemistry, cryochemistry, and heterogeneous catalysis. It therefore delivers novel and unique access to a variety of experimental approaches toward a broad choice of functional materials and their specific surface processes. The high-temperature (electro)catalysis manipulator is designed for probing solid state/gas phase interactions for heterogeneous catalysts including solid electrolyzer/fuel cell electrocatalysts at pressures up to 15 mbar and temperatures from room temperature to 1000 °C. The liquid electrochemistry manipulator is specifically designed for in situ spectroscopic investigations of polarized solid/liquid interfaces using aqueous electrolytes and the third one for experiments for ice and ice-like materials at cryogenic temperatures to approximately -190 °C. The flexible and modular combination of these setups provides the opportunity to address a broad spectrum of in situ and operando XPS experiments on a laboratory-based system, circumventing the limited accessibility of experiments at synchrotron facilities.
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Affiliation(s)
- Leander Haug
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria
| | - Christoph Griesser
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria
| | - Christoph W Thurner
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria
| | - Daniel Winkler
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria
| | - Toni Moser
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria
| | - Marco Thaler
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria
| | - Pit Bartl
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria
| | - Manuel Rainer
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | | | - David Schumacher
- SPECS Surface Nano Analysis GmbH, Voltastraße 5, 13355 Berlin, Germany
| | - Karsten Dierschke
- SPECS Surface Nano Analysis GmbH, Voltastraße 5, 13355 Berlin, Germany
| | - Norbert Köpfle
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria
| | - Simon Penner
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria
| | - Martin K Beyer
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Thomas Loerting
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria
| | - Julia Kunze-Liebhäuser
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria
| | - Bernhard Klötzer
- Institute of Physical Chemistry, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria
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6
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Al-Shahumi TM, Al-Omari IA, Al-Harthi SH, Myint MTZ. Synthesis, structure, morphology, magnetism, and magnetocaloric-effect studies of (La1−xPrx)0.7Sr0.3MnO3 nanocrystalline perovskites. SN APPLIED SCIENCES 2023. [DOI: 10.1007/s42452-023-05328-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/31/2023] Open
Abstract
AbstractSingle-Phase (La1–xPrx)0.7Sr0.3MnO3 (x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0) perovskites were synthesized by the sol–gel method followed by sintering at 700 °C for 5 h. Samples with x = 0.0–0.4 are found to crystallize into rhombohedral structure (R-3c space group) while the ones with x = 0.6–1.0 crystallize into orthorhombic structure (Pbnm space group). The average particle size of the samples was in the range of 21–44 nm. All samples exhibit a ferromagnetic to paramagnetic second-order magnetic phase transition at Curie temperature, which is found to decrease linearly with increasing the Pr concentration. The magnetic coercivity was found to be small (~ 10 Oe) for all the samples, at T < TC. The experimental effective paramagnetic moment (µeff) is found to increase with increasing x from 3.99 µB (x = 0.0) to 5.05 µB (x = 1.0). The magnitude of the maximum magnetic entropy change (−ΔSM)max. and the relative cooling power (RCP) for the samples having orthorhombic structure increases as x increases reaching a maximum value of 4.67 J/kg.K and 574 J/kg at ΔµoH = 9 T for x = 1.0. While the ones with the rhombohedral structure have the maximum values of (−ΔSM)max. and RCP of 4.63 J/kg.K and 472 J/kg at ΔµoH = 9 T are for x = 0.2. The large values of (−ΔSM)max. and RCP (at room temperature (RT)) and the wider temperature range of −ΔSM for the sample with x = 0.6 suggests that this compound may be considered as magnetic refrigerant material at RT, and the other compounds can be candidates in the vicinity of RT.
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7
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Siebenhofer M, Nenning A, Wilson GE, Kilner JA, Rameshan C, Kubicek M, Fleig J, Blaha P. Electronic and ionic effects of sulphur and other acidic adsorbates on the surface of an SOFC cathode material. JOURNAL OF MATERIALS CHEMISTRY. A 2023; 11:7213-7226. [PMID: 37007913 PMCID: PMC10044886 DOI: 10.1039/d3ta00978e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 03/03/2023] [Indexed: 06/19/2023]
Abstract
The effects of sulphur adsorbates and other typical solid oxide fuel cell (SOFC) poisons on the electronic and ionic properties of an SrO-terminated (La,Sr)CoO3 (LSC) surface and on its oxygen exchange kinetics have been investigated experimentally with near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS), low energy ion scattering (LEIS) and impedance spectroscopy as well as computationally with density functional theory (DFT). The experiment shows that trace amounts of sulphur in measurement atmospheres form SO2- 4 adsorbates and strongly deactivate a pristine LSC surface. They induce a work function increase, indicating a changing surface potential and a surface dipole. DFT calculations reveal that the main participants in these charge transfer processes are not sub-surface transition metals, but surface oxygen atoms. The study further shows that sulphate adsorbates strongly affect oxygen vacancy formation energies in the LSC (sub-)surface, thus affecting defect concentrations and oxygen transport properties. To generalize these results, the investigation was extended to other acidic oxides which are technologically relevant as SOFC cathode poisons, such as CO2 and CrO3. The results unveil a clear correlation of work function changes and redistributed charge with the Smith acidity of the adsorbed oxide and clarify fundamental mechanistic details of atomic surface modifications. The impact of acidic adsorbates on various aspects of the oxygen exchange reaction rate is discussed in detail.
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Affiliation(s)
- Matthäus Siebenhofer
- Centre for Electrochemistry and Surface Technology, CEST Wr. Neustadt Austria
- Institute of Chemical Technologies and Analytics, TU Wien Vienna Austria
| | - Andreas Nenning
- Institute of Chemical Technologies and Analytics, TU Wien Vienna Austria
| | | | | | | | - Markus Kubicek
- Institute of Chemical Technologies and Analytics, TU Wien Vienna Austria
| | - Jürgen Fleig
- Institute of Chemical Technologies and Analytics, TU Wien Vienna Austria
| | - Peter Blaha
- Institute of Materials Chemistry, TU Wien Vienna Austria
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8
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Punga L, Abbassi A, Toma M, Alupului T, Doroftei C, Dobromir M, Timpu D, Doroftei F, Hrostea L, Rusu GG, Razouk A, Iacomi F. Studies of the Structure and Optical Properties of BaSrMgWO 6 Thin Films Deposited by a Spin-Coating Method. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:2756. [PMID: 36014622 PMCID: PMC9414463 DOI: 10.3390/nano12162756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Revised: 08/08/2022] [Accepted: 08/09/2022] [Indexed: 06/15/2023]
Abstract
Highly transparent thin films with the chemical formula BaSrMgWO6 were deposited by spin coating using a solution of nitrates of Ba, Sr, and Mg and ammonium paratungstate in dimethylformamide with a Ba:Sr:Mg:W ratio = 1:1:1:1. XRD, SEM, EDX, and XPS investigations evidenced that annealing at 800 °C for 1 h results in an amorphous structure having a precipitate on its surface, and that supplementary annealing at 850 °C for 45 min forms a nanocrystalline structure and dissolves a portion of the precipitates. A textured double perovskite cubic structure (61.9%) was found, decorated with tetragonal and cubic impurity phases (12.7%), such as BaO2, SrO2, and MgO, and an under-stoichiometric phase (24.4%) with the chemical formula Ba2-(x+y) SrxMgyWO5. From transmittance measurements, the values of the optical band gap were estimated for the amorphous (Egdir = 5.21 eV, Egind = 3.85 eV) and nanocrystalline (Egdir = 4.69 eV, Egind = 3.77 eV) phases. The presence of a lattice disorder was indicated by the high Urbach energy values and weak absorption tail energies. A decrease in their values was observed and attributed to the crystallization process, lattice strain diminution, and cation redistribution.
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Affiliation(s)
- Luciana Punga
- Faculty of Physics, Alexandru Ioan Cuza University of Iasi, 11 Carol I Blvd., 700506 Iasi, Romania
| | - Abderrahman Abbassi
- LRPSI, Polydisciplinary Faculty of Beni-Mellal, Sultan Moulay Slimane University, Mghila BP 592, Beni-Mellal 23000, Morocco
| | - Mihaela Toma
- Faculty of Physics, Alexandru Ioan Cuza University of Iasi, 11 Carol I Blvd., 700506 Iasi, Romania
| | - Teodor Alupului
- Faculty of Physics, Alexandru Ioan Cuza University of Iasi, 11 Carol I Blvd., 700506 Iasi, Romania
| | - Corneliu Doroftei
- CERNESIM-ICI, Alexandru Ioan Cuza University of Iasi, 11 Carol I Blvd., 700506 Iasi, Romania
| | - Marius Dobromir
- Department of Exact and Natural Sciences, Institute of Interdisciplinary Research, Alexandru Ioan Cuza University of Iasi, 11 Carol I Blvd., 700506 Iasi, Romania
| | - Daniel Timpu
- Petru Poni Institute of Macromolecular Chemistry, 1A Grigore Ghica Voda Alley, 700487 Iasi, Romania
| | - Florica Doroftei
- Petru Poni Institute of Macromolecular Chemistry, 1A Grigore Ghica Voda Alley, 700487 Iasi, Romania
| | - Laura Hrostea
- RAMTECH, Institute of Interdisciplinary Research, Alexandru Ioan Cuza University of Iasi, 11 Carol I Blvd., 700506 Iasi, Romania
| | - George G. Rusu
- Faculty of Physics, Alexandru Ioan Cuza University of Iasi, 11 Carol I Blvd., 700506 Iasi, Romania
| | - Abdelati Razouk
- LGEM, FST, Sultan Moulay Slimane University, BP 523, Beni-Mellal 23000, Morocco
| | - Felicia Iacomi
- Faculty of Physics, Alexandru Ioan Cuza University of Iasi, 11 Carol I Blvd., 700506 Iasi, Romania
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9
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Roy KS, Hettler S, Arenal R, Panchakarla LS. Strontium-deficient Sr xCoO 2-CoO 2 nanotubes as a high ampacity and high conductivity material. MATERIALS HORIZONS 2022; 9:2115-2127. [PMID: 35766405 DOI: 10.1039/d1mh01987b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Continuous miniaturization of electronics demands the development of interconnectors with high ampacity and high conductivity, which conventional conductors such as copper and gold cannot offer. Here we report the synthesis of Sr-deficient misfit SrxCoO2-CoO2 nanotubes by a novel crystal conversion method and investigate their electrical properties. Bulk Sr6Co5O15 having a quasi-one-dimensional CoO6 polyhedral structure (face-sharing octahedron and trigonal prismatic CoO6 arranged in one-dimension) is converted to SrxCoO2-CoO2 nanotubes where CoO2 adopts a two-dimensional edge-sharing CoO2 layered structure in a basic hydrothermal process. Electrical properties measured on individual nanotubes demonstrate that these nanotubes are semiconducting with a conductivity of 1.28 × 104 S cm-1 and an ampacity of 109 A cm-2, which is the highest reported ampacity value to date of any inorganic oxide-based material. The nanotubes also show a breakdown power per unit channel length (P/L) of ∼38.3 W cm-1, the highest among the regularly used interconnect materials. The above results demonstrate that SrxCoO2-CoO2 nanotubes are potential building blocks for high-power electronic applications.
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Affiliation(s)
- Kankona Singha Roy
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Simon Hettler
- Instituto de Nanociencia y Materiales de Aragon (INMA), CSIC-Universidad de Zaragoza, Calle Pedro Cerbuna 12, 50009 Zaragoza, Spain.
- Laboratorio de Microscopias Avanzadas (LMA), Universidad de Zaragoza, Calle Mariano Esquillor, 50018 Zaragoza, Spain
| | - Raul Arenal
- Instituto de Nanociencia y Materiales de Aragon (INMA), CSIC-Universidad de Zaragoza, Calle Pedro Cerbuna 12, 50009 Zaragoza, Spain.
- Laboratorio de Microscopias Avanzadas (LMA), Universidad de Zaragoza, Calle Mariano Esquillor, 50018 Zaragoza, Spain
- ARAID Foundation, 50018 Zaragoza, Spain
| | - Leela S Panchakarla
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
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10
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Reversely trapping atoms from a perovskite surface for high-performance and durable fuel cell cathodes. Nat Catal 2022. [DOI: 10.1038/s41929-022-00764-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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11
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Highly Efficient Adsorption of Sr 2+ and Co 2+ Ions by Ambient Prepared Alkali Activated Metakaolin. Polymers (Basel) 2022; 14:polym14050992. [PMID: 35267815 PMCID: PMC8912444 DOI: 10.3390/polym14050992] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 02/26/2022] [Accepted: 02/26/2022] [Indexed: 02/05/2023] Open
Abstract
This study aimed to explore a low cost and sustainable adsorbent to remove Sr2+ and Co2+ ions, which are major radioactive ions in nuclear wastewater. The material properties of the alkali-activated metakaoline as a function of soaking time at ambient temperature from 1 day to 7 days were examined by XRD, XRF, SEM, and solid-state NMR. Adsorption isotherms were used to evaluate the appropriate soaking time for the optimal sorption performance for both Sr2+ and Co2+ ions. The alkali-activated metakaolin soaked for 3 days (BK3) presented the maximum adsorption capacities of 3.81 meq/g (167.5 mg/g) and 4.02 meq/g (118.5 mg/g) for Sr2+ and Co2+, respectively. The sorption mechanisms for Sr2+ and Co2+ in the BK3 sample were investigated, and the experimental results indicated that adsorption for Sr2+ was achieved via ion exchange. By contrast, surface complexation in combination with ion exchange contributed to the sorption mechanisms for the removal of Co2+. Competitive adsorption experiments revealed that the alkali-activated metakaolin favored the adsorption for divalent ions (i.e., Sr2+ and Co2+), and it was less effective for Cs+. Finally, the used adsorbent could be directly mineralized and vitrified by heat treatment to immobilize the Sr2+ and Co2+ ions.
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12
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Chemical Degradation of the La0.6Sr0.4Co0.2Fe0.8O3−δ/Ce0.8Sm0.2O2−δ Interface during Sintering and Cell Operation. ENERGIES 2021. [DOI: 10.3390/en14123674] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
A complete cell consisting of NiO-Ce0.8Sm0.2O3−δ//Ce0.8Sm0.2O3−δ//(La0.6Sr0.4)0.95Co0.2Fe0.8O3−δ elaborated by a co-tape casting and co-sintering process and tested in operating fuel cell conditions exhibited a strong degradation in performance over time. Study of the cathode–electrolyte interface after cell testing showed, on one hand, the diffusion of lanthanum from (La0.6Sr0.4)0.95Co0.2Fe0.8O3−δ into Sm-doped ceria leading to a La- and Sm-doped ceria phase. On the other hand, Ce and Sm diffused into the perovskite phase of the cathode. The grain boundaries appear to be the preferred pathways of the cation diffusion. Furthermore, a strontium enrichment was clearly observed both in the (La0.6Sr0.4)0.95Co0.2Fe0.8O3−δ layer and at the interface with electrolyte. X-ray photoelectron spectroscopy (XPS) indicates that this Sr-rich phase corresponded to SrCO3. These different phenomena led to a chemical degradation of materials and interfaces, explaining the decrease in electrochemical performance.
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Porotnikova N, Farlenkov A, Naumov S, Vlasov M, Khodimchuk A, Fetisov A, Ananyev M. Effect of grain boundaries in La 0.84Sr 0.16CoO 3-δ on oxygen diffusivity and surface exchange kinetics. Phys Chem Chem Phys 2021; 23:11272-11286. [PMID: 33972961 DOI: 10.1039/d1cp01099a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The single crystal and polycrystalline specimens of La0.84Sr0.16CoO3-δ oxide were synthesized and characterized by X-ray powder diffraction analysis, energy dispersive X-ray microanalysis, the electron backscatter diffraction technique, and X-ray photoelectron spectroscopy. A thin slab was prepared from the grown single crystal with its surface corresponding to the (110) plane. The kinetics of the oxygen exchange between the gas phase and a single crystal and a polycrystalline specimen was studied by means of 16O/18O oxygen isotope exchange at T = 750-850 °C and PO2 = 5.3 × 10-3-2.2 × 10-2 atm. Temperature dependencies of the oxygen heterogeneous exchange rate, the oxygen dissociative adsorption and incorporation rates, and oxygen diffusion coefficients were obtained. The relationship between the crystallographic orientation of oxides and the kinetic parameters of oxides has been established. Correlations between the surface state and the rates of individual stages of oxygen exchange as well as oxygen diffusion pathways in the single crystal compared with those in the polycrystalline specimen are considered.
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Affiliation(s)
- Natalia Porotnikova
- Institute of High Temperature Electrochemistry, UB RAS, Ekaterinburg, Russia.
| | - Andrei Farlenkov
- Ural Federal University named after the First President of Russia B.N. Yeltsin, Ekaterinburg, Russia
| | - Sergey Naumov
- Institute of Metal Physics, UB RAS, Ekaterinburg, Russia
| | - Maxim Vlasov
- Institute of High Temperature Electrochemistry, UB RAS, Ekaterinburg, Russia.
| | - Anna Khodimchuk
- Institute of High Temperature Electrochemistry, UB RAS, Ekaterinburg, Russia.
| | | | - Maxim Ananyev
- Ural Federal University named after the First President of Russia B.N. Yeltsin, Ekaterinburg, Russia
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Zaidi S, Asikin-Mijan N, Hussain A, Mastuli MS, Alharthi FA, Alghamdi AA, Taufiq-Yap Y. Facile synthesis of nanosized La/ZrO2 catalysts for ketonization of free fatty acid and biomass feedstocks. J Taiwan Inst Chem Eng 2021. [DOI: 10.1016/j.jtice.2021.04.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Kelley KP, Sharma V, Zhang W, Baddorf AP, Nascimento VB, Vasudevan RK. Exotic Long-Range Surface Reconstruction on La 0.7Sr 0.3MnO 3 Thin Films. ACS APPLIED MATERIALS & INTERFACES 2021; 13:9166-9173. [PMID: 33566561 DOI: 10.1021/acsami.0c20166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Due to an extremely diverse phase space, La1-xSrxMnO3, as with other manganites, offers a wide range of tunability and applications including colossal magnetoresistance and use as spin-polarized electrodes. Here, we study an unprecedented, exotic surface reconstruction (6 × 6) in La1-xSrxMnO3 (x = 0.3) observed via low-energy electron diffraction (LEED). Scanning tunneling microscopy (STM) shows the surface is relatively flat, with unit-cell step heights, and X-ray photoelectron spectroscopy (XPS) reveals a strong degree of Sr segregation at the surface. By combining electron diffraction and first-principles computations, we propose that the long-range surface reconstruction consists of a Sr-segregated surface with La (6 × 6) ordering. This study expands our understanding of manganite systems and underscores their ability to form interesting surface reconstructions, driven largely by cation segregation that can potentially be controlled for tuning surface ordering.
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Affiliation(s)
- Kyle P Kelley
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Vinit Sharma
- National Institute for Computational Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
- Joint Institute for Computational Sciences, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Wenrui Zhang
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Arthur P Baddorf
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Von B Nascimento
- Departamento de Física, Universidade Federal de Minas Gerais, Avenida Antônio Carlos, 6627, Belo Horizonte 31270-901, MG, Brazil
| | - Rama K Vasudevan
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
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Lindenthal L, Ruh T, Rameshan R, Summerer H, Nenning A, Herzig C, Löffler S, Limbeck A, Opitz AK, Blaha P, Rameshan C. Ca-doped rare earth perovskite materials for tailored exsolution of metal nanoparticles. ACTA CRYSTALLOGRAPHICA SECTION B, STRUCTURAL SCIENCE, CRYSTAL ENGINEERING AND MATERIALS 2020; 76:1055-1070. [PMID: 33289717 DOI: 10.1107/s2052520620013475] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 10/07/2020] [Indexed: 06/12/2023]
Abstract
Perovskite-type oxide materials (nominal composition ABO3) are a very versatile class of materials, and their properties are tuneable by varying and doping A- and B-site cations. When the B-site contains easily reducible cations (e.g. Fe, Co or Ni), these can exsolve under reducing conditions and form metallic nanoparticles on the surface. This process is very interesting as a novel route for the preparation of catalysts, since oxide surfaces decorated with finely dispersed catalytically active (often metallic) nanoparticles are a key requirement for excellent catalyst performance. Five doped perovskites, namely, La0.9Ca0.1FeO3-δ, La0.6Ca0.4FeO3-δ, Nd0.9Ca0.1FeO3-δ, Nd0.6Ca0.4FeO3-δ and Nd0.6Ca0.4Fe0.9Co0.1O3-δ, have been synthesized and characterized by experimental and theoretical methods with respect to their crystal structures, electronic properties, morphology and exsolution behaviour. All are capable of exsolving Fe and/or Co. Special emphasis has been placed on the influence of the A-site elemental composition on structure and exsolution capability. Using Nd instead of La increased structural distortions and, at the same time, hindered exsolution. Increasing the amount of Ca doping also increased distortions and additionally changed the Fe oxidation states, resulting in exsolution being shifted to higher temperatures as well. Using the easily reducible element Co as the B-site dopant significantly facilitated the exsolution process and led to much smaller and homogeneously distributed exsolved particles. Therefore, the Co-doped perovskite is a promising material for applications in catalysis, even more so as Co is catalytically a highly active element. The results show that fine-tuning of the perovskite composition will allow tailored exsolution of nanoparticles, which can be used for highly sophisticated catalyst design.
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Affiliation(s)
- Lorenz Lindenthal
- Institute of Materials Chemistry, TU Wien, Getreidmarkt 9/165, Vienna 1060, Austria
| | - Thomas Ruh
- Institute of Materials Chemistry, TU Wien, Getreidmarkt 9/165, Vienna 1060, Austria
| | - Raffael Rameshan
- Institute of Materials Chemistry, TU Wien, Getreidmarkt 9/165, Vienna 1060, Austria
| | - Harald Summerer
- Institute of Materials Chemistry, TU Wien, Getreidmarkt 9/165, Vienna 1060, Austria
| | - Andreas Nenning
- Institute of Chemical Technologies and Analytics, TU Wien, Getreidmarkt 9/164, Vienna 1060, Austria
| | - Christopher Herzig
- Institute of Chemical Technologies and Analytics, TU Wien, Getreidmarkt 9/164, Vienna 1060, Austria
| | - Stefan Löffler
- USTEM, TU Wien, Wiedner Hauptstraße 8-10/E057-02, Vienna 1060, Austria
| | - Andreas Limbeck
- Institute of Chemical Technologies and Analytics, TU Wien, Getreidmarkt 9/164, Vienna 1060, Austria
| | - Alexander Karl Opitz
- Institute of Chemical Technologies and Analytics, TU Wien, Getreidmarkt 9/164, Vienna 1060, Austria
| | - Peter Blaha
- Institute of Materials Chemistry, TU Wien, Getreidmarkt 9/165, Vienna 1060, Austria
| | - Christoph Rameshan
- Institute of Materials Chemistry, TU Wien, Getreidmarkt 9/165, Vienna 1060, Austria
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Novel Sample-Stage for Combined Near Ambient Pressure X-ray Photoelectron Spectroscopy, Catalytic Characterization and Electrochemical Impedance Spectroscopy. CRYSTALS 2020. [DOI: 10.3390/cryst10100947] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
For an in-depth characterization of catalytic materials and their properties, spectroscopic in-situ (operando) investigations are indispensable. With the rapid development of advanced commercial spectroscopic equipment, it is possible to combine complementary methods in a single system. This allows for simultaneously gaining insights into surface and bulk properties of functional oxides, such as defect chemistry, catalytic characteristics, electronic structure, etc., enabling a direct correlation of structure and reactivity of catalyst materials, thus facilitating effective catalyst development. Here, we present a novel sample-stage, which was specifically developed to pave the way to a lab–based combination of near ambient pressure X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy with simultaneous catalytic operando measurements. This setup is designed to probe different (model) systems under conditions close to real heterogeneous catalysis, with a focus on solid oxide electrochemical cells. In a proof of concept experiment using an electrochemical model cell with the doped perovskite Nd0.6Ca0.4Fe0.9Co0.1O3-δ as working electrode, the precise control of the surface chemistry that is possible with this setup is demonstrated. The exsolution behavior of the material was studied, showing that at a lower temperature (500 °C) with lower reducing potential of the gas phase, only cobalt was exsolved, forming metallic particles on the surface of the perovskite-type oxide. Only when the temperature was increased to 600 °C and a cathodic potential was applied (−250 mV) Fe also started to be released from the perovskite lattice.
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Acidity of surface-infiltrated binary oxides as a sensitive descriptor of oxygen exchange kinetics in mixed conducting oxides. Nat Catal 2020. [DOI: 10.1038/s41929-020-00520-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Celikbilek O, Cavallaro A, Kerherve G, Fearn S, Chaix-Pluchery O, Aguadero A, Kilner JA, Skinner SJ. Surface Restructuring of Thin-Film Electrodes Based on Thermal History and Its Significance for the Catalytic Activity and Stability at the Gas/Solid and Solid/Solid Interfaces. ACS APPLIED MATERIALS & INTERFACES 2020; 12:34388-34401. [PMID: 32627535 PMCID: PMC7467561 DOI: 10.1021/acsami.0c08308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 07/06/2020] [Indexed: 06/11/2023]
Abstract
Electrodes in solid-state energy devices are subjected to a variety of thermal treatments, from film processing to device operation at high temperatures. All these treatments influence the chemical activity and stability of the films, as the thermally induced chemical restructuring shapes the microstructure and the morphology. Here, we investigate the correlation between the oxygen reduction reaction (ORR) activity and thermal history in complex transition metal oxides, in particular, La0.6Sr0.4CoO3-δ (LSC64) thin films deposited by pulsed laser deposition. To this end, three ∼200 nm thick LSC64 films with different processing and thermal histories were studied. A variety of surface-sensitive elemental characterization techniques (i.e., low-energy ion scattering, X-ray photoelectron spectroscopy, and secondary ion mass spectrometry) were employed to thoroughly investigate the cationic distribution from the outermost surface to the film/substrate interface. Moreover, electrochemical impedance spectroscopy was used to study the activity and the stability of the films. Our investigations revealed that, despite the initial comparable ORR activity at 600 °C, the degradation rates of the films differed by twofold in the long-term stability tests at 500 °C. Here, we emphasize the importance of processing and thermal history in the elemental surface distribution, especially for the stability of LSC64 electrodes and propose that they should be considered as among the main pillars in the design of active surfaces.
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Affiliation(s)
- Ozden Celikbilek
- Department
of Materials, Imperial College London, Prince Consort Road, London SW7 2BP, United Kingdom
| | - Andrea Cavallaro
- Department
of Materials, Imperial College London, Prince Consort Road, London SW7 2BP, United Kingdom
| | - Gwilherm Kerherve
- Department
of Materials, Imperial College London, Prince Consort Road, London SW7 2BP, United Kingdom
| | - Sarah Fearn
- Department
of Materials, Imperial College London, Prince Consort Road, London SW7 2BP, United Kingdom
| | | | - Ainara Aguadero
- Department
of Materials, Imperial College London, Prince Consort Road, London SW7 2BP, United Kingdom
| | - John A. Kilner
- Department
of Materials, Imperial College London, Prince Consort Road, London SW7 2BP, United Kingdom
- International
Institute for Carbon-Neutral Energy Research (I2CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Stephen J. Skinner
- Department
of Materials, Imperial College London, Prince Consort Road, London SW7 2BP, United Kingdom
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Sambalova O, Billeter E, Mann J, Miyayama T, Burnat D, Heel A, Bleiner D, Borgschulte A. Hard and soft X‐ray photoelectron spectroscopy for selective probing of surface and bulk chemical compositions in a perovskite‐type Ni catalyst. SURF INTERFACE ANAL 2020. [DOI: 10.1002/sia.6843] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Olga Sambalova
- Laboratory of Advanced Analytical Technologies Empa Materials Science and Technology Dübendorf Switzerland
- Department of Chemistry University of Zürich Zürich Switzerland
| | - Emanuel Billeter
- Laboratory of Advanced Analytical Technologies Empa Materials Science and Technology Dübendorf Switzerland
- Department of Chemistry University of Zürich Zürich Switzerland
| | - Jennifer Mann
- Analytical Laboratory Physical Electronics Chanhassen Minnesota USA
| | | | - Dariusz Burnat
- Institute of Materials and Process Engineering (IMPE) Zurich University of Applied Sciences (ZHAW) Winterthur Switzerland
| | - Andre Heel
- Institute of Materials and Process Engineering (IMPE) Zurich University of Applied Sciences (ZHAW) Winterthur Switzerland
| | - Davide Bleiner
- Laboratory of Advanced Analytical Technologies Empa Materials Science and Technology Dübendorf Switzerland
- Department of Chemistry University of Zürich Zürich Switzerland
| | - Andreas Borgschulte
- Laboratory of Advanced Analytical Technologies Empa Materials Science and Technology Dübendorf Switzerland
- Department of Chemistry University of Zürich Zürich Switzerland
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