1
|
Bumberger AE, Nenning A, Fleig J. Transmission line revisited - the impedance of mixed ionic and electronic conductors. Phys Chem Chem Phys 2024; 26:15068-15089. [PMID: 38752774 DOI: 10.1039/d4cp00975d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2024]
Abstract
This contribution provides a comprehensive guide for evaluating the one-dimensional impedance response of dense mixed ionic and electronic conductors based on a physically derived transmission line model. While mass and charge transport through the bulk of a mixed conductor is always described by three fundamental parameters (chemical capacitance, ionic conductivity and electronic conductivity), it is the nature of the contact interfaces that largely determines the observed impedance response. Thus, to allow an intuitive adaptation of the transmission line model for any specific measurement situation, the physical meanings of terminal impedance elements at the ionic and electronic rail ends are explicitly discussed. By distinguishing between charge transfer terminals and electrochemical reaction terminals, the range of possible measurement configurations is categorized into symmetrical, SOFC-type and battery-type setups, all of which are explored on the basis of practical examples from the literature. Also, the transformation of an SOFC electrode into a battery electrode and the relevance of side reactions for the impedance of battery electrodes is discussed.
Collapse
Affiliation(s)
| | - Andreas Nenning
- Institute of Chemical Technologies and Analytics, TU Wien, Vienna, Austria.
| | - Juergen Fleig
- Institute of Chemical Technologies and Analytics, TU Wien, Vienna, Austria.
| |
Collapse
|
2
|
Schmid A, Baiutti F, Tarancon A, Fleig J. A High Temperature Harvestorer Based on a Photovoltaic Cell and an Oxygen Ion Battery. ACS APPLIED ENERGY MATERIALS 2024; 7:205-213. [PMID: 38213554 PMCID: PMC10777342 DOI: 10.1021/acsaem.3c02494] [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: 10/04/2023] [Revised: 11/30/2023] [Accepted: 11/30/2023] [Indexed: 01/13/2024]
Abstract
Hybrid devices for combined energy harvesting and storage, i.e., harvestorers, are attractive solutions for powering small autonomous devices (e.g., "smart appliances", Internet of things nodes), which are ever more prominent as the digitalization and technologization of our society progresses. A concept for a high temperature (HT) harvestorer is presented, and the operational characteristics of a prototype device are discussed. It is based on photovoltaic (PV) energy harvesting and HT electrochemical energy storage. The HT-PV cells employ SrTiO3/La0.9Sr0.1CrO3-δ heterojunctions for energy harvesting and produce photovoltages up to 1 V and photocurrents of several mA cm-2 upon UV illumination at 350 °C. Electrochemical energy storage is realized by oxygen ion battery (OIB), a device based on mixed ionic and electronic conducting oxide thin film electrodes and an yttria stabilized zirconia electrolyte. The OIB exhibits capacities of up to 11 mC cm-2 (3 μA h cm-2) at 0.6 V (350 °C). A prototype harvestorer device was fabricated by integrating an HT-PV and an OIB cell into one device. This harvestorer was operated over several cycles consisting of harvesting and storing energy under illumination, followed by retrieval of the stored energy without illumination. Up to 3.5 mJ cm-2 (1 μW h cm-2) was stored with energy efficiencies up to 67%. Approaches for further optimization are discussed.
Collapse
Affiliation(s)
- Alexander Schmid
- Institute
of Chemical Technologies and Analytics, TU Wien, Getreidemarkt 9, Vienna 1060, Austria
| | - Federico Baiutti
- Catalonia
Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, 2a pl, 08930 Sant Adrià del Besòs, Barcelona, Spain
| | - Albert Tarancon
- Catalonia
Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, 2a pl, 08930 Sant Adrià del Besòs, Barcelona, Spain
- Catalan
Institution for Research and Advanced Studies (ICREA), Passeig Lluís Companys 23, 08010 Barcelona, Spain
| | - Jürgen Fleig
- Institute
of Chemical Technologies and Analytics, TU Wien, Getreidemarkt 9, Vienna 1060, Austria
| |
Collapse
|
3
|
Yang K, Lu Y, Hu Y, Xu Z, Zheng J, Chen H, Wang J, Yu Y, Zhang H, Liu Z, Lu Q. Differentiating Oxygen Exchange Reaction Mechanisms across Phase Boundaries. J Am Chem Soc 2023; 145:25806-25814. [PMID: 37971728 DOI: 10.1021/jacs.3c09693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Abstract
Triggering phase transitions by controlling the anion stoichiometry is an effective method of tuning the electrocatalytic activity of the functional oxides. However, understanding the potential differences in the reaction mechanism(s) of different phases requires the accurate mapping of phase boundaries during the electrochemical reactions, which can be quite challenging. In this work, we have established a feasible electrochemical method based on the measurement of chemical capacitance to resolve the critical stoichiometry at phase boundaries under operando conditions. We select a simple binary oxide PrOx as a proof-of-principle model system, which shows excellent activity for high-temperature oxygen incorporation and evolution reactions (OIR/OER). We show that the phase transition can be sensitively probed by quantifying the chemical capacitance, which can be further used for differentiating the OIR/OER mechanisms across the phase boundary of PrOx. Therefore, our findings provide a new framework for exploring phase engineering as a tool for the design of electrocatalysts.
Collapse
Affiliation(s)
- Kaichuang Yang
- School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310058, China
- School of Engineering, Westlake University, Hangzhou, Zhejiang 310024, China
| | - Ying Lu
- School of Engineering, Westlake University, Hangzhou, Zhejiang 310024, China
| | - Yang Hu
- School of Engineering, Westlake University, Hangzhou, Zhejiang 310024, China
| | - Zihan Xu
- School of Engineering, Westlake University, Hangzhou, Zhejiang 310024, China
| | - Jieping Zheng
- School of Engineering, Westlake University, Hangzhou, Zhejiang 310024, China
| | - Haowen Chen
- School of Engineering, Westlake University, Hangzhou, Zhejiang 310024, China
| | - Jingle Wang
- School of Engineering, Westlake University, Hangzhou, Zhejiang 310024, China
| | - Yi Yu
- School of Physical Science and Technology and Center for Transformative Science, ShanghaiTech University, Shanghai 201210, China
| | - Hui Zhang
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
| | - Zhi Liu
- School of Physical Science and Technology and Center for Transformative Science, ShanghaiTech University, Shanghai 201210, China
| | - Qiyang Lu
- School of Engineering, Westlake University, Hangzhou, Zhejiang 310024, China
- Research Center for Industries of the Future, Westlake University, Hangzhou, Zhejiang 310030, China
| |
Collapse
|
4
|
Bumberger AE, Ražnjević S, Zhang Z, Friedbacher G, Fleig J. Chemical capacitance measurements reveal the impact of oxygen vacancies on the charge curve of LiNi 0.5Mn 1.5O 4-δ thin films. JOURNAL OF MATERIALS CHEMISTRY. A 2023; 11:24072-24088. [PMID: 38014361 PMCID: PMC10644792 DOI: 10.1039/d3ta05086f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 10/15/2023] [Indexed: 11/29/2023]
Abstract
The level of oxygen deficiency δ in high-voltage spinels of the composition LiNi0.5Mn1.5O4-δ (LNMO) significantly influences the thermodynamic and kinetic properties of the material, ultimately affecting the cell performance of the corresponding lithium-ion batteries. This study presents a comprehensive defect chemical analysis of LNMO thin films with oxygen vacancy concentrations of 2.4% and 0.53%, focusing particularly on the oxygen vacancy regime around 4 V versus Li+/Li. A set of electrochemical properties is extracted from impedance measurements as a function of state-of-charge for the full tetrahedral-site regime (3.8 to 4.9 V versus Li+/Li). A defect chemical model (Brouwer diagram) is derived from the data, providing a coherent explanation for all important trends of the electrochemical properties and charge curve. Highly resolved chemical capacitance measurements allow a refining of the defect model for the oxygen vacancy regime, showing that a high level of oxygen deficiency not only impacts the amount of redox active Mn3+/4+, but also promotes the trapping of electrons in proximity to an oxygen vacancy. The resulting stabilisation of Mn3+ thereby mitigates the voltage reduction in the oxygen vacancy regime. These findings offer valuable insights into the complex influence of oxygen deficiency on the performance of lithium-ion batteries based on LNMO.
Collapse
Affiliation(s)
| | | | - Zaoli Zhang
- Erich Schmid Institute for Materials Science Leoben Austria
| | - Gernot Friedbacher
- Institute of Chemical Technologies and Analytics, TU Wien Vienna Austria
| | - Juergen Fleig
- Institute of Chemical Technologies and Analytics, TU Wien Vienna Austria
| |
Collapse
|
5
|
Bumberger AE, Boehme C, Ring J, Raznjevic S, Zhang Z, Kubicek M, Fleig J. Defect Chemistry of Spinel Cathode Materials-A Case Study of Epitaxial LiMn 2O 4 Thin Films. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2023; 35:5135-5149. [PMID: 37456594 PMCID: PMC10339684 DOI: 10.1021/acs.chemmater.3c00814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 06/02/2023] [Indexed: 07/18/2023]
Abstract
Spinels of the general formula Li2-δM2O4 are an essential class of cathode materials for Li-ion batteries, and their optimization in terms of electrode potential, accessible capacity, and charge/discharge kinetics relies on an accurate understanding of the underlying solid-state mass and charge transport processes. In this work, we report a comprehensive impedance study of sputter-deposited epitaxial Li2-δMn2O4 thin films as a function of state-of-charge for almost the entire tetrahedral-site regime (1 ≤ δ ≤ 1.9) and provide a complete set of electrochemical properties, consisting of the charge-transfer resistance, ionic conductivity, volume-specific chemical capacitance, and chemical diffusivity. The obtained properties vary by up to three orders of magnitude and provide essential insights into the point defect concentration dependences of the overall electrode potential. We introduce a defect chemical model based on simple concentration dependences of the Li chemical potential, considering the tetrahedral and octahedral lattice site restrictions defined by the spinel crystal structure. The proposed model is in excellent qualitative and quantitative agreement with the experimental data, excluding the two-phase regime around 4.15 V. It can easily be adapted for other transition metal stoichiometries and doping states and is thus applicable to the defect chemical analysis of all spinel-type cathode materials.
Collapse
Affiliation(s)
| | - Christin Boehme
- Institute
of Chemical Technologies and Analytics, TU Wien, Vienna 1060, Austria
| | - Joseph Ring
- Institute
of Chemical Technologies and Analytics, TU Wien, Vienna 1060, Austria
| | - Sergej Raznjevic
- Erich
Schmid Institute of Materials Science, Leoben 8700, Austria
| | - Zaoli Zhang
- Erich
Schmid Institute of Materials Science, Leoben 8700, Austria
| | - Markus Kubicek
- Institute
of Chemical Technologies and Analytics, TU Wien, Vienna 1060, Austria
| | - Juergen Fleig
- Institute
of Chemical Technologies and Analytics, TU Wien, Vienna 1060, Austria
| |
Collapse
|
6
|
Summerer H, Nenning A, Rameshan C, Opitz AK. Exsolved catalyst particles as a plaything of atmosphere and electrochemistry. EES CATALYSIS 2023; 1:274-289. [PMID: 37213935 PMCID: PMC10193834 DOI: 10.1039/d2ey00036a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 03/20/2023] [Indexed: 05/23/2023]
Abstract
A new type of catalyst preparation yields its active sites not by infiltration but exsolution of reducible transition metals of its own host lattice. These exsolution catalysts offer a high dispersion of catalytically active particles, slow agglomeration, and the possibility of reactivation after poisoning due to redox cycling. The formation of exsolved particles by partial decomposition of the host lattice can be driven by applying a sufficiently reducing atmosphere, elevated temperatures but also by a cathodic bias voltage (provided the host perovskite is an electrode on an oxide ion conducting electrolyte). In addition, such an electrochemical polarisation can change the oxidation state and thus the catalytic activity of exsolved particles. In this work, we investigate the electrochemical switching between an active and an inactive state of iron particles exsolved from thin film mixed conducting model electrodes, namely La0.6Sr0.4FeO3-δ (LSF) and Nd0.6Ca0.4FeO3-δ (NCF), in humid hydrogen atmospheres. We show that the transition between two activity states exhibits a hysteresis-like behaviour in the electrochemical I-V characteristics. Ambient pressure XPS measurements proofed that this hysteresis is linked to the oxidation and reduction of iron particles. Furthermore, it is demonstrated that the surface kinetics of the host material itself has only a negligible impact on the particle exsolution, and that the main impact factors are the surrounding atmosphere as well as the applied electrochemical overpotential. In particular, we suggest a 'kinetic competition' between gas atmosphere and oxygen chemical potential in the mixed conducting electrode and discuss possible ways of how this process takes place.
Collapse
Affiliation(s)
- Harald Summerer
- TU Wien, Institute of Chemical Technologies and Analytics, Getreidemarkt 9/164-EC 1060 Vienna Austria
- TU Wien, Institute of Materials Chemistry, Getreidemarkt 9/165-PC 1060 Vienna Austria
| | - Andreas Nenning
- TU Wien, Institute of Chemical Technologies and Analytics, Getreidemarkt 9/164-EC 1060 Vienna Austria
| | - Christoph Rameshan
- TU Wien, Institute of Materials Chemistry, Getreidemarkt 9/165-PC 1060 Vienna Austria
| | - Alexander K Opitz
- TU Wien, Institute of Chemical Technologies and Analytics, Getreidemarkt 9/164-EC 1060 Vienna Austria
| |
Collapse
|
7
|
Krammer M, Schmid A, Nenning A, Bumberger AE, Siebenhofer M, Herzig C, Limbeck A, Rameshan C, Kubicek M, Fleig J. Closed-Pore Formation in Oxygen Electrodes for Solid Oxide Electrolysis Cells Investigated by Impedance Spectroscopy. ACS APPLIED MATERIALS & INTERFACES 2023; 15:8076-8092. [PMID: 36729502 PMCID: PMC9940111 DOI: 10.1021/acsami.2c20731] [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: 11/17/2022] [Accepted: 01/19/2023] [Indexed: 06/18/2023]
Abstract
Electrochemical impedance spectroscopy was used to investigate the chemical capacitance of La0.6Sr0.4CoO3-δ (LSC) thin-film electrodes under anodic polarization (i.e., in the electrolysis mode). For this purpose, electrodes with different microstructures were prepared via pulsed-laser deposition. Analysis of dense electrodes and electrodes with open porosity revealed decreasing chemical capacitances with increasing anodic overpotentials, as expected from defect chemical considerations. However, extremely high chemical capacitance peaks with values in the range of 104 F/cm3 at overpotentials of >140 mV were obtained after annealing for several hours in synthetic air and/or after applying high anodic bias voltages of >750 mV. From the results of several surface analysis techniques and transmission electron microscopy, it is concluded that closed pores develop upon both of these treatments: (i) During annealing, initially open pores get closed by SrSO4, which forms due to strontium segregation in measurement gases with minute traces of sulfur. (ii) The bias treatment causes mechanical failure and morphological changes including closed pores in the bulk of dense films. Under anodic polarization, high-pressure oxygen accumulates in those closed pores, and this causes the capacitance peak. Model calculations based on a real-gas equation allow us to properly predict the experimentally obtained capacitance increase. We demonstrate that analysis of the chemical capacitance of oxygen electrodes in solid oxide electrolysis cells can thus be used as a nondestructive observation tool to detect and quantify closed porosity with a lower detection limit between 10-4 and 10-3.
Collapse
Affiliation(s)
- Martin Krammer
- Institute
of Chemical Technologies and Analytics, Technische Universität (TU) Wien, Getreidemarkt 9/164-EC, 1060Vienna, Austria
| | - Alexander Schmid
- Institute
of Chemical Technologies and Analytics, Technische Universität (TU) Wien, Getreidemarkt 9/164-EC, 1060Vienna, Austria
| | - Andreas Nenning
- Institute
of Chemical Technologies and Analytics, Technische Universität (TU) Wien, Getreidemarkt 9/164-EC, 1060Vienna, Austria
| | - Andreas Ewald Bumberger
- Institute
of Chemical Technologies and Analytics, Technische Universität (TU) Wien, Getreidemarkt 9/164-EC, 1060Vienna, Austria
| | - Matthäus Siebenhofer
- Institute
of Chemical Technologies and Analytics, Technische Universität (TU) Wien, Getreidemarkt 9/164-EC, 1060Vienna, Austria
- Centre
for Electrochemical Surface Technology GmbH, Viktor-Kaplan-Straße 2, 2700Wiener Neustadt, Austria
| | - Christopher Herzig
- Institute
of Chemical Technologies and Analytics, Technische Universität (TU) Wien, Getreidemarkt 9/164-EC, 1060Vienna, Austria
| | - Andreas Limbeck
- Institute
of Chemical Technologies and Analytics, Technische Universität (TU) Wien, Getreidemarkt 9/164-EC, 1060Vienna, Austria
| | - Christoph Rameshan
- Institute
of Material Chemistry, Technische Universität
(TU) Wien, Getreidemarkt
9/165-PC, 1060Vienna, Austria
- Chair
of Physical Chemistry, Montanuniversität
Leoben, Franz-Josef-Straße
18, 8700Leoben, Austria
| | - Markus Kubicek
- Institute
of Chemical Technologies and Analytics, Technische Universität (TU) Wien, Getreidemarkt 9/164-EC, 1060Vienna, Austria
| | - Juergen Fleig
- Institute
of Chemical Technologies and Analytics, Technische Universität (TU) Wien, Getreidemarkt 9/164-EC, 1060Vienna, Austria
| |
Collapse
|
8
|
Riedl C, Siebenhofer M, Ražnjević S, Bumberger AE, Zhang Z, Limbeck A, Opitz AK, Kubicek M, Fleig J. In situ electrochemical observation of anisotropic lattice contraction of La 0.6Sr 0.4FeO 3-δ electrodes during pulsed laser deposition. Phys Chem Chem Phys 2022; 25:142-153. [PMID: 36476841 PMCID: PMC9768847 DOI: 10.1039/d2cp04977e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
La0.6Sr0.4FeO3-δ (LSF) electrodes were grown on different electrolyte substrates by pulsed laser deposition (PLD) and their oxygen exchange reaction (OER) resistance was tracked in real-time by in situ PLD impedance spectroscopy (i-PLD) inside the PLD chamber. This enables measurements on pristine surfaces free from any contaminations and the direct observation of thickness dependent properties. As substrates, yttria-stabilized zirconia single crystals (YSZ) were used for polycrystalline LSF growth and La0.95Sr0.05Ga0.95Mg0.05O3-δ (LSGM) single crystals or YSZ single crystals with a 5 nm buffer-layer of Gd0.2Ce0.8O2-δ for epitaxial LSF film growth. While polycrystalline LSF electrodes show a constant OER resistance in a broad thickness range, epitaxially grown LSF electrodes exhibit a continuous and strong increase of the OER resistance with film thickness until ≈60 nm. In addition, the activation energy of the OER resistance increases by 0.23 eV compared to polycrystalline LSF. High resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) measurements reveal an increasing contraction of the out-of-plane lattice parameter in the epitaxial LSF electrodes over electrode thickness. Defect thermodynamic simulations suggest that the decrease of the LSF unit cell volume is accompanied by a lowering of the oxygen vacancy concentration, explaining both the resistive increase and the increased activation energy.
Collapse
Affiliation(s)
- Christoph Riedl
- Institute of Chemical Technologies and Analytics, TU WienViennaAustria
| | - Matthäus Siebenhofer
- Institute of Chemical Technologies and Analytics, TU WienViennaAustria,Centre for Electrochemistry and Surface Technology, CEST, WrNeustadtAustria
| | | | | | - Zaoli Zhang
- Erich Schmid Institute for Materials ScienceLeobenAustria
| | - Andreas Limbeck
- Institute of Chemical Technologies and Analytics, TU WienViennaAustria
| | | | - Markus Kubicek
- Institute of Chemical Technologies and Analytics, TU WienViennaAustria
| | - Jürgen Fleig
- Institute of Chemical Technologies and Analytics, TU WienViennaAustria
| |
Collapse
|
9
|
Krammer M, Schmid A, Siebenhofer M, Bumberger AE, Herzig C, Limbeck A, Kubicek M, Fleig J. Formation and Detection of High-Pressure Oxygen in Closed Pores of La 0.6Sr 0.4CoO 3-δ Solid Oxide Electrolysis Anodes. ACS APPLIED ENERGY MATERIALS 2022; 5:8324-8335. [PMID: 35909806 PMCID: PMC9326814 DOI: 10.1021/acsaem.2c00888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The chemical capacitance of La0.6Sr0.4CoO3-δ (LSC) thin film microelectrodes with different microstructures was investigated upon varying anodic DC voltages. Dense and porous electrodes (open porosity) were prepared by using different parameters during pulsed laser deposition (PLD). Furthermore, electrodes with closed porosity were fabricated by depositing a dense capping layer on a porous film. Electrochemical impedance spectroscopy (EIS) was performed in synthetic air at 460 and 608 °C with anodic DC voltages up to 440 mV. Chemical capacitance values of the electrodes were derived from the obtained spectra. While the chemical capacitance of dense and porous electrodes decreased as expected with increasing anodic overpotential, electrodes with closed pores exhibited very unusual peaks with extremely high values of >8000 F/cm3 at overpotentials of >100 mV. We demonstrate that this huge capacitance increase agrees very well with calculated chemical capacitances deduced from a real gas equation. Hence, we conclude that the formation of highly pressurized oxygen (up to gas pressures of ∼104 bar) in closed pores is responsible for this strong capacitive effect at anodic overpotentials. Such measurements can thus detect and quantify the buildup of high internal gas pressures in closed pores at the anode side of solid oxide electrolysis cells.
Collapse
Affiliation(s)
- Martin Krammer
- TU
Wien, Institute of Chemical
Technologies and Analytics, Getreidemarkt 9/164-EC, 1060 Vienna, Austria
| | - Alexander Schmid
- TU
Wien, Institute of Chemical
Technologies and Analytics, Getreidemarkt 9/164-EC, 1060 Vienna, Austria
| | - Matthäus Siebenhofer
- TU
Wien, Institute of Chemical
Technologies and Analytics, Getreidemarkt 9/164-EC, 1060 Vienna, Austria
- Centre
for Electrochemical Surface Technology GmbH, Viktor-Kaplan-Straßze 2, 2700 Wiener Neustadt, Austria
| | - Andreas Ewald Bumberger
- TU
Wien, Institute of Chemical
Technologies and Analytics, Getreidemarkt 9/164-EC, 1060 Vienna, Austria
| | - Christopher Herzig
- TU
Wien, Institute of Chemical
Technologies and Analytics, Getreidemarkt 9/164-EC, 1060 Vienna, Austria
| | - Andreas Limbeck
- TU
Wien, Institute of Chemical
Technologies and Analytics, Getreidemarkt 9/164-EC, 1060 Vienna, Austria
| | - Markus Kubicek
- TU
Wien, Institute of Chemical
Technologies and Analytics, Getreidemarkt 9/164-EC, 1060 Vienna, Austria
| | - Juergen Fleig
- TU
Wien, Institute of Chemical
Technologies and Analytics, Getreidemarkt 9/164-EC, 1060 Vienna, Austria
| |
Collapse
|
10
|
Riedl C, Siebenhofer M, Nenning A, Schmid A, Weiss M, Rameshan C, Limbeck A, Kubicek M, Opitz AK, Fleig J. In situ techniques reveal the true capabilities of SOFC cathode materials and their sudden degradation due to omnipresent sulfur trace impurities. JOURNAL OF MATERIALS CHEMISTRY. A 2022; 10:14838-14848. [PMID: 35923869 PMCID: PMC9295724 DOI: 10.1039/d2ta03335f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 06/22/2022] [Indexed: 06/15/2023]
Abstract
In this study, five different mixed conducting cathode materials were grown as dense thin films by pulsed laser deposition (PLD) and characterized via in situ impedance spectroscopy directly after growth inside the PLD chamber (i-PLD). This technique enables quantification of the oxygen reduction kinetics on pristine and contaminant-free mixed conducting surfaces. The measurements reveal excellent catalytic performance of all pristine materials with polarization resistances being up to two orders of magnitude lower than those previously reported in the literature. For instance, on dense La0.6Sr0.4CoO3-δ thin films, an area specific surface resistance of ∼0.2 Ω cm2 at 600 °C in synthetic air was found, while values usually >1 Ω cm2 are measured in conventional ex situ measurement setups. While surfaces after i-PLD measurements were very clean, ambient pressure X-ray photoelectron spectroscopy (AP-XPS) measurements found that all samples measured in other setups were contaminated with sulfate adsorbates. In situ impedance spectroscopy during AP-XPS revealed that already trace amounts of sulfur present in high purity gases accumulate quickly on pristine surfaces and lead to strongly increased surface polarization resistances, even before the formation of a SrSO4 secondary phase. Accordingly, the inherent excellent catalytic properties of this important class of materials were often inaccessible so far. As a proof of concept, the fast kinetics observed on sulfate-free surfaces were also realized in ex situ measurements with a gas purification setup and further reduces the sulfur concentration in the high purity gas.
Collapse
Affiliation(s)
- Christoph Riedl
- Institute of Chemical Technologies and Analytics, TU Wien Getreidemarkt 9-E164 1060 Vienna Austria
| | - Matthäus Siebenhofer
- Institute of Chemical Technologies and Analytics, TU Wien Getreidemarkt 9-E164 1060 Vienna Austria
- CEST Kompetenzzentrum für Elektrochemische Oberflächentechnologie GmbH, TFZ - Wiener Neustadt Viktor-Kaplan-Strasse 2 2700 Wiener Neustadt Austria
| | - Andreas Nenning
- Institute of Chemical Technologies and Analytics, TU Wien Getreidemarkt 9-E164 1060 Vienna Austria
| | - Alexander Schmid
- Institute of Chemical Technologies and Analytics, TU Wien Getreidemarkt 9-E164 1060 Vienna Austria
| | - Maximilian Weiss
- Institute of Chemical Technologies and Analytics, TU Wien Getreidemarkt 9-E164 1060 Vienna Austria
| | - Christoph Rameshan
- Institute of Materials Chemistry, TU Wien Getreidemarkt 9-E165-PC 1060 Vienna Austria
| | - Andreas Limbeck
- Institute of Chemical Technologies and Analytics, TU Wien Getreidemarkt 9-E164 1060 Vienna Austria
| | - Markus Kubicek
- Institute of Chemical Technologies and Analytics, TU Wien Getreidemarkt 9-E164 1060 Vienna Austria
| | - Alexander Karl Opitz
- Institute of Chemical Technologies and Analytics, TU Wien Getreidemarkt 9-E164 1060 Vienna Austria
| | - Juergen Fleig
- Institute of Chemical Technologies and Analytics, TU Wien Getreidemarkt 9-E164 1060 Vienna Austria
| |
Collapse
|
11
|
Huang R, Carr CG, Gopal CB, Haile SM. Broad Applicability of Electrochemical Impedance Spectroscopy to the Measurement of Oxygen Nonstoichiometry in Mixed Ion and Electron Conductors. ACS APPLIED MATERIALS & INTERFACES 2022; 14:19629-19643. [PMID: 35467847 DOI: 10.1021/acsami.2c05417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Oxygen nonstoichiometry is a fundamental feature of mixed ion and electron conductors (MIECs). In this work, a general electrochemical method for determining nonstoichiometry in thin film MIECs, via measurement of the chemical capacitance, is demonstrated using ceria and ceria-zirconia (Ce0.8Zr0.2O2-δ) as representative materials. A.C. impedance data are collected from both materials at high temperature (750-900 °C) under reducing conditions with oxygen partial pressure (pO2) in the range 10-13 to 10-20 atm. Additional measurements of ceria-zirconia films are made under relatively oxidizing conditions with pO2 in the range 0.2 to 10-4 atm and temperatures of 800-900 °C. Under reducing conditions, the impedance spectra are described by a simple circuit in which a resistor is in series with a resistor and capacitor in parallel, and thickness-dependent measurements are used to resolve the capacitance into interfacial and chemical terms. Under more oxidizing conditions, the impedance spectra (of Ce0.8Zr0.2O2-δ) reveal an additional diffusional feature, which enables determination of the ionic resistance of the film in addition to the capacitance, and hence the transport properties. A generalized mathematical formalism is presented for recovering the nonstoichiometry from the chemical capacitance, without recourse to defect chemical models. The ceria nonstoichiometry values are in good agreement with literature values determined by thermogravimetric measurements but display considerably less scatter and are collected on considerably shorter time scales. The thermodynamic analysis of Ce0.8Zr0.2O2-δ corroborates earlier findings that introduction of Zr into ceria enhances its reducibility.
Collapse
Affiliation(s)
- Ruiyun Huang
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Connor G Carr
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Chirranjeevi Balaji Gopal
- Department of Materials Science, California Institute of Technology, Pasadena, California 91125, United States
| | - Sossina M Haile
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Department of Applied Physics, Northwestern University, Evanston, Illinois 60208, United States
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| |
Collapse
|
12
|
Tang Y, Chiabrera F, Morata A, Cavallaro A, Liedke MO, Avireddy H, Maller M, Butterling M, Wagner A, Stchakovsky M, Baiutti F, Aguadero A, Tarancón A. Ion Intercalation in Lanthanum Strontium Ferrite for Aqueous Electrochemical Energy Storage Devices. ACS APPLIED MATERIALS & INTERFACES 2022; 14:18486-18497. [PMID: 35412787 DOI: 10.1021/acsami.2c01379] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Ion intercalation of perovskite oxides in liquid electrolytes is a very promising method for controlling their functional properties while storing charge, which opens up its potential application in different energy and information technologies. Although the role of defect chemistry in oxygen intercalation in a gaseous environment is well established, the mechanism of ion intercalation in liquid electrolytes at room temperature is poorly understood. In this study, the defect chemistry during ion intercalation of La0.5Sr0.5FeO3-δ thin films in alkaline electrolytes is studied. Oxygen and proton intercalation into the La1-xSrxFeO3-δ perovskite structure is observed at moderate electrochemical potentials (0.5 to -0.4 V), giving rise to a change in the oxidation state of Fe (as a charge compensation mechanism). The variation of the concentration of holes as a function of the intercalation potential is characterized by in situ ellipsometry, and the concentration of electron holes is indirectly quantified for different electrochemical potentials. Finally, a dilute defect chemistry model that describes the variation of defect species during ionic intercalation is developed.
Collapse
Affiliation(s)
- Yunqing Tang
- Department of Advanced Materials for Energy Applications, Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, 08930 Sant Adrià del Besòs, Barcelona, Spain
| | - Francesco Chiabrera
- Department of Advanced Materials for Energy Applications, Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, 08930 Sant Adrià del Besòs, Barcelona, Spain
- Department of Energy Conversion and Storage, Functional Oxides Group, Technical University of Denmark, Fysikvej 310, 233, 2800 Kongens Lyngby, Denmark
| | - Alex Morata
- Department of Advanced Materials for Energy Applications, Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, 08930 Sant Adrià del Besòs, Barcelona, Spain
| | - Andrea Cavallaro
- Department of Materials, Imperial College London, London SW7 2AZ, U.K
| | - Maciej O Liedke
- Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
| | - Hemesh Avireddy
- Department of Advanced Materials for Energy Applications, Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, 08930 Sant Adrià del Besòs, Barcelona, Spain
| | - Mar Maller
- Department of Advanced Materials for Energy Applications, Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, 08930 Sant Adrià del Besòs, Barcelona, Spain
| | - Maik Butterling
- Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
| | - Andreas Wagner
- Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
| | - Michel Stchakovsky
- HORIBA Scientific, 14 Boulevard Thomas Gobert, Passage Jobin Yvon, CS 45002-91120 Palaiseau, France
| | - Federico Baiutti
- Department of Advanced Materials for Energy Applications, Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, 08930 Sant Adrià del Besòs, Barcelona, Spain
- Department of Materials Chemistry, National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia
| | - Ainara Aguadero
- Department of Materials, Imperial College London, London SW7 2AZ, U.K
- Instituto de Ciencia de Materiales de Madrid, ICMM-CSIC, Sor Juana Ines de la Cruz 3, 28049 Madrid, Spain
| | - Albert Tarancón
- Department of Advanced Materials for Energy Applications, Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, 08930 Sant Adrià del Besòs, Barcelona, Spain
- ICREA, Passeig Lluís Companys 23, 08010 Barcelona, Spain
| |
Collapse
|
13
|
|
14
|
Riedl C, Siebenhofer M, Nenning A, Friedbacher G, Weiss M, Rameshan C, Bernardi J, Limbeck A, Kubicek M, Opitz AK, Fleig J. Performance modulation through selective, homogenous surface doping of lanthanum strontium ferrite electrodes revealed by in situ PLD impedance measurements. JOURNAL OF MATERIALS CHEMISTRY. A 2022; 10:2973-2986. [PMID: 35223041 PMCID: PMC8823903 DOI: 10.1039/d1ta08634k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 12/03/2021] [Indexed: 06/14/2023]
Abstract
Accelerating the oxygen reduction kinetics of solid oxide fuel cell (SOFC) cathodes is crucial to improve their efficiency and thus to provide the basis for an economically feasible application of intermediate temperature SOFCs. In this work, minor amounts of Pt were doped into lanthanum strontium ferrite (LSF) thin film electrodes to modulate the material's oxygen exchange performance. Surprisingly, Pt was found to be incorporated on the B-site of the perovskite electrode as non metallic Pt4+. The polarization resistance of LSF thin film electrodes with and without additional Pt surface doping was compared directly after film growth employing in situ electrochemical impedance spectroscopy inside a PLD chamber (i-PLD). This technique enables observation of the polarization resistance of pristine electrodes unaltered by degradation or any external contamination of the electrode surface. Moreover, growth of multi-layers of materials with different compositions on the very same single crystalline electrolyte substrate combined with in situ impedance measurements allow excellent comparability of different materials. Even a 5 nm layer of Pt doped LSF (1.5 at% Pt), i.e. a Pt loading of 80 ng cm-2, improved the polarization resistance by a factor of about 2.5. In addition, p(O2) and temperature dependent impedance measurements on both pure and Pt doped LSF were performed in situ and obtained similar activation energies and p(O2) dependence of the polarization resistance, which allow us to make far reaching mechanistic conclusions indicating that Pt4+ introduces additional active sites.
Collapse
Affiliation(s)
- Christoph Riedl
- Institute of Chemical Technologies and Analytics, TU Wien Getreidemarkt 9-E164 1060 Vienna Austria
| | - Matthäus Siebenhofer
- Institute of Chemical Technologies and Analytics, TU Wien Getreidemarkt 9-E164 1060 Vienna Austria
- CEST Kompetenzzentrum für elektrochemische Oberflächentechnologie GmbH TFZ - Wiener Neustadt Viktor-Kaplan-Strasse 2 2700 Wiener Neustadt Austria
| | - Andreas Nenning
- Institute of Chemical Technologies and Analytics, TU Wien Getreidemarkt 9-E164 1060 Vienna Austria
| | - Gernot Friedbacher
- Institute of Chemical Technologies and Analytics, TU Wien Getreidemarkt 9-E164 1060 Vienna Austria
| | - Maximilian Weiss
- Institute of Chemical Technologies and Analytics, TU Wien Getreidemarkt 9-E164 1060 Vienna Austria
| | - Christoph Rameshan
- Institute of Materials Chemistry, TU Wien Getreidemarkt 9-E165-PC 1060 Vienna Austria
| | - Johannes Bernardi
- USTEM Universitäre Service-Einrichtung für Transmissions-Elektronenmikroskopie, TU Wien Wiedner Hauptstrasse. 8-10 1040 Wien Austria
| | - Andreas Limbeck
- Institute of Chemical Technologies and Analytics, TU Wien Getreidemarkt 9-E164 1060 Vienna Austria
| | - Markus Kubicek
- Institute of Chemical Technologies and Analytics, TU Wien Getreidemarkt 9-E164 1060 Vienna Austria
| | - Alexander Karl Opitz
- Institute of Chemical Technologies and Analytics, TU Wien Getreidemarkt 9-E164 1060 Vienna Austria
| | - Juergen Fleig
- Institute of Chemical Technologies and Analytics, TU Wien Getreidemarkt 9-E164 1060 Vienna Austria
| |
Collapse
|
15
|
Siebenhofer M, Riedl C, Schmid A, Limbeck A, Opitz AK, Fleig J, Kubicek M. Investigating oxygen reduction pathways on pristine SOFC cathode surfaces by in situ PLD impedance spectroscopy. JOURNAL OF MATERIALS CHEMISTRY. A 2022; 10:2305-2319. [PMID: 35223039 PMCID: PMC8805794 DOI: 10.1039/d1ta07128a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 11/04/2021] [Indexed: 06/14/2023]
Abstract
The oxygen exchange reaction mechanism on truly pristine surfaces of SOFC cathode materials (La0.6Sr0.4CoO3-δ = LSC, La0.6Sr0.4FeO3-δ = LSF, (La0.6Sr0.4)0.98Pt0.02FeO3-δ = Pt:LSF, SrTi0.3Fe0.7O3-δ = STF, Pr0.1Ce0.9O2-δ = PCO and La0.6Sr0.4MnO3-δ = LSM) was investigated employing in situ impedance spectroscopy during pulsed laser deposition (i-PLD) over a wide temperature and p(O2) range. Besides demonstrating the often astonishing catalytic capabilities of the materials, it is possible to discuss the oxygen exchange reaction mechanism based on experiments on clean surfaces unaltered by external degradation processes. All investigated materials with at least moderate ionic conductivity (i.e. all except LSM) exhibit polarization resistances with very similar p(O2)- and T-dependences, mostly differing only in absolute value. In combination with non-equilibrium measurements under polarization and defect chemical model calculations, these results elucidate several aspects of the oxygen exchange reaction mechanism and refine the understanding of the role oxygen vacancies and electronic charge carriers play in the oxygen exchange reaction. It was found that a major part of the effective activation energy of the surface exchange reaction, which is observed during equilibrium measurements, originates from thermally activated charge carrier concentrations. Electrode polarization was therefore used to control defect concentrations and to extract concentration amended activation energies, which prove to be drastically different for oxygen incorporation and evolution (0.26 vs. 2.05 eV for LSF).
Collapse
Affiliation(s)
- Matthäus Siebenhofer
- Institute of Chemical Technologies and Analytics, TU Wien Vienna Austria
- CEST Centre of Electrochemistry and Surface Technology Wr. Neustadt Austria
| | - Christoph Riedl
- Institute of Chemical Technologies and Analytics, TU Wien Vienna Austria
| | - Alexander Schmid
- Institute of Chemical Technologies and Analytics, TU Wien Vienna Austria
| | - Andreas Limbeck
- 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
| |
Collapse
|
16
|
Weiss M, Riedl C, Frank J, Fleig J, Limbeck A. Quantitative analysis of the platinum surface decoration on lanthanum strontium iron oxide thin films via online-LASIL-ICP-MS. Microchem J 2021. [DOI: 10.1016/j.microc.2021.106236] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
17
|
Progress in Material Development for Low-Temperature Solid Oxide Fuel Cells: A Review. ENERGIES 2021. [DOI: 10.3390/en14051280] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Solid oxide fuel cells (SOFCs) have been considered as promising candidates to tackle the need for sustainable and efficient energy conversion devices. However, the current operating temperature of SOFCs poses critical challenges relating to the costs of fabrication and materials selection. To overcome these issues, many attempts have been made by the SOFC research and manufacturing communities for lowering the operating temperature to intermediate ranges (600–800 °C) and even lower temperatures (below 600 °C). Despite the interesting success and technical advantages obtained with the low-temperature SOFC, on the other hand, the cell operation at low temperature could noticeably increase the electrolyte ohmic loss and the polarization losses of the electrode that cause a decrease in the overall cell performance and energy conversion efficiency. In addition, the electrolyte ionic conductivity exponentially decreases with a decrease in operating temperature based on the Arrhenius conduction equation for semiconductors. To address these challenges, a variety of materials and fabrication methods have been developed in the past few years which are the subject of this critical review. Therefore, this paper focuses on the recent advances in the development of new low-temperature SOFCs materials, especially low-temperature electrolytes and electrodes with improved electrochemical properties, as well as summarizing the matching current collectors and sealants for the low-temperature region. Different strategies for improving the cell efficiency, the impact of operating variables on the performance of SOFCs, and the available choice of stack designs, as well as the costing factors, operational limits, and performance prospects, have been briefly summarized in this work.
Collapse
|
18
|
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.
Collapse
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
| |
Collapse
|
19
|
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.
Collapse
|
20
|
Hauser D, Nenning A, Opitz AK, Klötzer B, Penner S. Spectro-electrochemical setup for in situ and operando mechanistic studies on metal oxide electrode surfaces. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:084104. [PMID: 32872960 DOI: 10.1063/5.0007435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 07/26/2020] [Indexed: 06/11/2023]
Abstract
This work shows a combined setup of Diffuse Reflectance FT-IR Spectroscopy (DRIFTS) and electrochemical characterization by AC and DC methods for in situ and operando investigations of surface species during CO2 electrolysis on metal oxide electrodes and their correlation with electrochemical activity. A high-temperature reaction chamber enables conducting DRIFTS and electrochemical experiments simultaneously at temperatures up to 1000 °C in both reductive and oxidative reaction atmospheres and under anodic and cathodic polarization conditions. A dedicated gas- and electrical feedthrough solution is presented, which is the key element required for recording electrochemical AC and DC characteristics using an electrochemical cell, which is simultaneously studied by DRIFTS experiments under realistic operation conditions. Selected results, obtained on a gadolinium doped ceria model solid oxide electrolysis cell upon different polarization states, demonstrate the basic functionality and capabilities of the setup and show how the simultaneous DRIFT-spectroscopic and electrochemical investigation of the surface and bulk chemistry on electrode materials leads to increased insight in the population of potential intermediates during CO2 electrolysis. With infrared spectroscopy and impedance spectroscopy as common and complementary spectroscopic methods in material science, the setup is considered to exhibit a huge potential in a wide field of fundamental and applied mechanistic research.
Collapse
Affiliation(s)
- Daniel Hauser
- Institute of Physical Chemistry, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Andreas Nenning
- Institute of Chemical Technologies and Analytics, TU Wien, A-1040 Vienna, Austria
| | - Alexander K Opitz
- Institute of Chemical Technologies and Analytics, TU Wien, A-1040 Vienna, Austria
| | - Bernhard Klötzer
- Institute of Physical Chemistry, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Simon Penner
- Institute of Physical Chemistry, University of Innsbruck, A-6020 Innsbruck, Austria
| |
Collapse
|
21
|
The Relation of Microstructure, Materials Properties and Impedance of SOFC Electrodes: A Case Study of Ni/GDC Anodes. ENERGIES 2020. [DOI: 10.3390/en13040987] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Detailed insight into electrochemical reaction mechanisms and rate limiting steps is crucial for targeted optimization of solid oxide fuel cell (SOFC) electrodes, especially for new materials and processing techniques, such as Ni/Gd-doped ceria (GDC) cermet anodes in metal-supported cells. Here, we present a comprehensive model that describes the impedance of porous cermet electrodes according to a transmission line circuit. We exemplify the validity of the model on electrolyte-supported symmetrical model cells with two equal Ni/Ce0.9Gd0.1O1.95-δ anodes. These anodes exhibit a remarkably low polarization resistance of less than 0.1 Ωcm2 at 750 °C and OCV, and metal-supported cells with equally prepared anodes achieve excellent power density of >2 W/cm2 at 700 °C. With the transmission line impedance model, it is possible to separate and quantify the individual contributions to the polarization resistance, such as oxygen ion transport across the YSZ-GDC interface, ionic conductivity within the porous anode, oxygen exchange at the GDC surface and gas phase diffusion. Furthermore, we show that the fitted parameters consistently scale with variation of electrode geometry, temperature and atmosphere. Since the fitted parameters are representative for materials properties, we can also relate our results to model studies on the ion conductivity, oxygen stoichiometry and surface catalytic properties of Gd-doped ceria and obtain very good quantitative agreement. With this detailed insight into reaction mechanisms, we can explain the excellent performance of the anode as a combination of materials properties of GDC and the unusual microstructure that is a consequence of the reductive sintering procedure, which is required for anodes in metal-supported cells.
Collapse
|
22
|
Pathway for electrochemical O2 incorporation. Nat Catal 2020. [DOI: 10.1038/s41929-020-0426-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
23
|
Chen D, Guan Z, Zhang D, Trotochaud L, Crumlin E, Nemsak S, Bluhm H, Tuller HL, Chueh WC. Constructing a pathway for mixed ion and electron transfer reactions for O2 incorporation in Pr0.1Ce0.9O2−x. Nat Catal 2020. [DOI: 10.1038/s41929-019-0401-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
24
|
Zablotsky D, Rusevich LL, Zvejnieks G, Kuzovkov V, Kotomin E. Manifestation of dipole-induced disorder in self-assembly of ferroelectric and ferromagnetic nanocubes. NANOSCALE 2019; 11:7293-7303. [PMID: 30938394 DOI: 10.1039/c9nr00708c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The colloidal processing of nearly monodisperse and highly crystalline single-domain ferroelectric or ferromagnetic nanocubes is a promising route to produce superlattice structures for integration into next-generation devices, whereas controlling the local behaviour of nanocrystals is imperative for fabricating highly-ordered assemblies. The current picture of nanoscale polarization in individual nanocrystals suggests a potential presence of a significant dipolar interaction, but its role in the condensation of nanocubes is unknown. We simulate the self-assembly of colloidal dipolar nanocubes under osmotic compression and perform the microstructural characterization of their densified ensembles. Our results indicate that the long-range positional and orientational correlations of perovskite nanocubes are highly sensitive to the presence of dipoles.
Collapse
Affiliation(s)
- Dmitry Zablotsky
- Institute of Solid State Physics, Kengaraga str. 8, LV-1063 Riga, Latvia
| | | | | | | | | |
Collapse
|
25
|
Heifets E, Kotomin EA, Bagaturyants AA, Maier J. Thermodynamic stability of non-stoichiometric SrFeO 3-δ: a hybrid DFT study. Phys Chem Chem Phys 2019; 21:3918-3931. [PMID: 30702110 DOI: 10.1039/c8cp07117a] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
SrFeO3-δ is a mixed ionic-electronic conductor with a complex magnetic structure that reveals a colossal magnetoresistance effect. This material and its solid solutions are attractive for various spintronic, catalytic and electrochemical applications, including cathodes for solid oxide fuel cells and permeation membranes. Its properties strongly depend on oxygen non-stoichiometry. Ab initio hybrid functional approach was applied herein to study the thermodynamic stability of a series of SrFeO3-δ compositions with several non-stoichiometries δ, ranging from 0 to 0.5 (SrFeO3-SrFeO2.875-SrFeO2.75-SrFeO2.5) as a function of temperature and oxygen pressure. The results obtained by two approaches, in which either (i) all electrons at Fe atoms explicitly described or (ii) inner core electrons at Fe atoms are replaced by effective core potential, are compared. Based on our calculations, phase diagrams were constructed, allowing the determination of environmental conditions for the existence of stable phases. It is shown that (within an employed model) only the SrFeO2.5 phase appears to be stable. The stability region for this phase was re-drawn on the contour map of oxygen chemical potential, presented as a function of temperature and oxygen partial pressure. A similar analysis was also performed using experimental Gibbs energies of perovskite formation from the elements. The present modelling strongly suggest a significant attraction between neutral oxygen vacancies. These vacancies are created during a series of the abovementioned SrFeO3-δ mutual transformations accompanied by oxygen release.
Collapse
Affiliation(s)
- Eugene Heifets
- Photochemistry Center, Federal Research Center "Crystallography and Photonics", Russian Academy of Sciences, Novatorov 7a, Moscow, 119421, Russia.
| | | | | | | |
Collapse
|
26
|
Schmid A, Rupp GM, Fleig J. How To Get Mechanistic Information from Partial Pressure-Dependent Current-Voltage Measurements of Oxygen Exchange on Mixed Conducting Electrodes. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2018; 30:4242-4252. [PMID: 30100672 PMCID: PMC6083415 DOI: 10.1021/acs.chemmater.8b00597] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 06/04/2018] [Indexed: 06/08/2023]
Abstract
The oxygen incorporation and evolution reaction on mixed conducting electrodes of solid oxide fuel or electrolysis cells involves gas molecules as well as ionic and electronic point defects in the electrode. The defect concentrations depend on the gas phase and can be modified by the overpotential. These interrelationships make a mechanistic analysis of partial pressure-dependent current-voltage experiments challenging. In this contribution it is described how to exploit this complex situation to unravel the kinetic roles of surface adsorbates and electrode point defects. Essential is a counterbalancing of oxygen partial pressure and dc electrode polarization such that the point defect concentrations in the electrode remain constant despite varying the oxygen partial pressure. It is exemplarily shown for La0.6Sr0.4FeO3-δ (LSF) thin film electrodes on yttria-stabilized zirconia how mechanistically relevant reaction orders can be obtained from current-voltage curves, measured in a three-electrode setup. This analysis strongly suggests electron holes as the limiting defect species for the oxygen evolution on LSF and reveals the dependence of the oxygen incorporation rate on the oxygen vacancy concentration. A virtual independence of the reaction rate from the oxygen partial pressure was empirically found for moderate oxygen pressures. This effect, however, arises from a counterbalancing of defect and adsorbate concentration changes.
Collapse
|