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Einert M, Waheed A, Lauterbach S, Mellin M, Rohnke M, Wagner LQ, Gallenberger J, Tian C, Smarsly BM, Jaegermann W, Hess F, Schlaad H, Hofmann JP. Sol-Gel-Derived Ordered Mesoporous High Entropy Spinel Ferrites and Assessment of Their Photoelectrochemical and Electrocatalytic Water Splitting Performance. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2205412. [PMID: 36653934 DOI: 10.1002/smll.202205412] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 12/19/2022] [Indexed: 06/17/2023]
Abstract
The novel material class of high entropy oxides with their unique and unexpected physicochemical properties is a candidate for energy applications. Herein, it is reported for the first time about the physico- and (photo-) electrochemical properties of ordered mesoporous (CoNiCuZnMg)Fe2 O4 thin films synthesized by a soft-templating and dip-coating approach. The A-site high entropy ferrites (HEF) are composed of periodically ordered mesopores building a highly accessible inorganic nanoarchitecture with large specific surface areas. The mesoporous spinel HEF thin films are found to be phase-pure and crack-free on the meso- and macroscale. The formation of the spinel structure hosting six distinct cations is verified by X-ray-based characterization techniques. Photoelectron spectroscopy gives insight into the chemical state of the implemented transition metals supporting the structural characterization data. Applied as photoanode for photoelectrochemical water splitting, the HEFs are photostable over several hours but show only low photoconductivity owing to fast surface recombination, as evidenced by intensity-modulated photocurrent spectroscopy. When applied as oxygen evolution reaction electrocatalyst, the HEF thin films possess overpotentials of 420 mV at 10 mA cm-2 in 1 m KOH. The results imply that the increase of the compositional disorder enhances the electronic transport properties, which are beneficial for both energy applications.
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Affiliation(s)
- Marcus Einert
- Surface Science Laboratory, Department of Materials and Earth Sciences, Technical University of Darmstadt, Otto-Berndt-Strasse 3, 64287, Darmstadt, Germany
| | - Arslan Waheed
- Surface Science Laboratory, Department of Materials and Earth Sciences, Technical University of Darmstadt, Otto-Berndt-Strasse 3, 64287, Darmstadt, Germany
| | - Stefan Lauterbach
- Institute for Applied Geosciences, Geomaterial Science, Technical University of Darmstadt, Schnittspahnstrasse 9, 64287, Darmstadt, Germany
| | - Maximilian Mellin
- Surface Science Laboratory, Department of Materials and Earth Sciences, Technical University of Darmstadt, Otto-Berndt-Strasse 3, 64287, Darmstadt, Germany
| | - Marcus Rohnke
- Center for Materials Research, Justus Liebig University Giessen, Heinrich-Buff-Ring 17, 35392, Giessen, Germany
| | - Lysander Q Wagner
- Center for Materials Research, Justus Liebig University Giessen, Heinrich-Buff-Ring 17, 35392, Giessen, Germany
- Institute for Physical Chemistry, Justus-Liebig University, Heinrich-Buff-Ring 17, 35392, Giessen, Germany
| | - Julia Gallenberger
- Surface Science Laboratory, Department of Materials and Earth Sciences, Technical University of Darmstadt, Otto-Berndt-Strasse 3, 64287, Darmstadt, Germany
| | - Chuanmu Tian
- Surface Science Laboratory, Department of Materials and Earth Sciences, Technical University of Darmstadt, Otto-Berndt-Strasse 3, 64287, Darmstadt, Germany
| | - Bernd M Smarsly
- Center for Materials Research, Justus Liebig University Giessen, Heinrich-Buff-Ring 17, 35392, Giessen, Germany
- Institute for Physical Chemistry, Justus-Liebig University, Heinrich-Buff-Ring 17, 35392, Giessen, Germany
| | - Wolfram Jaegermann
- Surface Science Laboratory, Department of Materials and Earth Sciences, Technical University of Darmstadt, Otto-Berndt-Strasse 3, 64287, Darmstadt, Germany
| | - Franziska Hess
- Institute of Chemistry, Technical University Berlin, Strasse des 17. Juni 124, 10623, Berlin, Germany
| | - Helmut Schlaad
- University of Potsdam, Institute of Chemistry, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
| | - Jan P Hofmann
- Surface Science Laboratory, Department of Materials and Earth Sciences, Technical University of Darmstadt, Otto-Berndt-Strasse 3, 64287, Darmstadt, Germany
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Lee JC, Woo JH, Lee HJ, Lee M, Woo H, Baek S, Nam J, Sim JY, Park S. Microfluidic Screening-Assisted Machine Learning to Investigate Vertical Phase Separation of Small Molecule:Polymer Blend. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2107596. [PMID: 34865268 DOI: 10.1002/adma.202107596] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 11/24/2021] [Indexed: 06/13/2023]
Abstract
Solution-based thin-film processing is a widely utilized technique for the fabrication of various devices. In particular, the tunability of the ink composition and coating condition allows precise control of thin-film properties and device performance. Despite the advantage of having such tunability, the sheer number of possible combinations of experimental parameters render it infeasible to efficiently optimize device performance and analyze the correlation between experimental parameters and device performance. In this work, a microfluidic screening-embedded thin-film processing technique is developed, through which thin-films of varying ratios of small molecule semiconductor:polymer blend are simultaneously generated and screened in a time- and resource-efficient manner. Moreover, utilizing the thin-films of varying combinations of experimental parameters, machine learning models are trained to predict the transistor performance. Gaussian Process Regression (GPR) algorithms tuned by Bayesian optimization shows the best predictive accuracy amongst the trained models, which enables narrowing down of the combinations of experimental parameters and investigation of the degree of vertical phase separation under the predicted parameter space. The technique can serve as a guideline for elucidating the underlying complex parameter-property-performance correlations in solution-based thin-film processing, thereby accelerating the optimization of various thin-film devices in the future.
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Affiliation(s)
- Jeong-Chan Lee
- Organic and nano electronics laboratory, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Seoul, 34141, Republic of Korea
| | - Jun Hee Woo
- Organic and nano electronics laboratory, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Seoul, 34141, Republic of Korea
| | - Ho-Jun Lee
- Organic and nano electronics laboratory, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Seoul, 34141, Republic of Korea
| | - Minho Lee
- School of Chemical and Biological Engineering and Institute of Chemical Process, Seoul National University, Seoul, 08826, Republic of Korea
| | - Heejin Woo
- Organic and nano electronics laboratory, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Seoul, 34141, Republic of Korea
| | - Seunghyeok Baek
- Organic and nano electronics laboratory, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Seoul, 34141, Republic of Korea
| | - Jaewook Nam
- School of Chemical and Biological Engineering and Institute of Chemical Process, Seoul National University, Seoul, 08826, Republic of Korea
| | - Joo Yong Sim
- Department of Mechanical Systems Engineering, Sookmyung Women's University, Seoul, 04310, Republic of Korea
| | - Steve Park
- KI for Health Science and Technology, Saudi Aramco-KAIST CO2 Management Center, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Seoul, 34141, Republic of Korea
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Transport Properties of Film and Bulk Sr0.98Zr0.95Y0.05O3−δ Membranes. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10072229] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In electrode-supported solid oxide fuel cells (SOFCs) with a thin electrolyte, the electrolyte performance can be affected by its interaction with the electrode, therefore, it is particularly important to study the charge transport properties of thin electrode-supported electrolytes. The transport numbers of charged species in Ni-cermet supported Sr0.98Zr0.95Y0.05O3−δ (SZY) membranes were studied and compared to those of the bulk membrane. SZY films of 2.5 μm thickness were fabricated by the chemical solution deposition technique. It was shown that the surface layer of the films contained 1.5–2 at.% Ni due to Ni diffusion from the substrate. The Ni-cermet supported 2.5 μm-thick membrane operating in the fuel cell mode was found to possess the effective transport number of oxygen ions of 0.97 at 550 °C, close to that for the bulk SZY membrane (0.99). The high ionic transport numbers indicate that diffusional interaction between SZY films and Ni-cermet supporting electrodes does not entail electrolyte degradation. The relationship between SZY conductivity and oxygen partial pressure was derived from the data on effective conductivity and ionic transport numbers for the membrane operating under two different oxygen partial pressure gradients—in air/argon and air/hydrogen concentration cells.
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Bowman WJ, Darbal A, Crozier PA. Linking Macroscopic and Nanoscopic Ionic Conductivity: A Semiempirical Framework for Characterizing Grain Boundary Conductivity in Polycrystalline Ceramics. ACS APPLIED MATERIALS & INTERFACES 2020; 12:507-517. [PMID: 31800213 DOI: 10.1021/acsami.9b15933] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Understanding the chemical and charge transport properties of grain boundaries (GBs) with high point defect concentrations (beyond the dilute solution limit) in polycrystalline materials is critical for developing ion-conducting solids for electrochemical energy conversion and storage. Elucidation and optimization of GBs are hindered by large variations in atomic structure, composition, and chemistry within nanometers or Ångstroms of the GB interface, which limits a fundamental understanding of electrical transport across and along GBs. Here we employ a novel correlated approach that is generally applicable to polycrystalline materials whose properties are affected by GB composition or chemistry. We demonstrate the connection between the nanoscopic chemical and transport properties of individual boundaries and the macroscopic ionic conductivity in oxygen-conducting Pr0.04Gd0.11Ce0.85O2-δ. The key finding is that GBs with higher solute concentration have lower activation energy for cross-GB ion conduction through a polycrystalline conductor. The resultant semiempirical framework presented here provides a tool for understanding, designing and optimizing polycrystalline ionic conductors.
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Affiliation(s)
- William J Bowman
- School for Engineering of Matter, Transport and Energy , Arizona State University , 501 E. Tyler Mall , Tempe , Arizona 85287-6106 , United States
| | - Amith Darbal
- Nanomegas USA , 1095 W. Rio Salado Pkwy #110 , Tempe , Arizona 85281 , United States
| | - Peter A Crozier
- School for Engineering of Matter, Transport and Energy , Arizona State University , 501 E. Tyler Mall , Tempe , Arizona 85287-6106 , United States
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Jeong SJ, Kwak NW, Byeon P, Chung SY, Jung W. Conductive Nature of Grain Boundaries in Nanocrystalline Stabilized Bi 2O 3 Thin-Film Electrolyte. ACS APPLIED MATERIALS & INTERFACES 2018; 10:6269-6275. [PMID: 29369610 DOI: 10.1021/acsami.7b16875] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Stabilized Bi2O3 has gained a considerable amount of attention as a solid electrolyte material for low-temperature solid oxide fuel cells due to its superior oxygen-ion conductivity at the temperature of relevance (≤500 °C). Despite many research efforts to measure the transport properties of stabilized Bi2O3, the effects of grain boundaries on the electrical conductivity have rarely been reported and their results are even controversial. Here, we attempt quantitatively to assess the grain boundary contribution out of the total ionic conductivity at elevated temperatures (350-500 °C) by fabricating epitaxial and nano-polycrystalline thin films of yttrium-stabilized Bi2O3. Surprisingly, both epitaxial and polycrystalline films show nearly identical levels of ionic conductivity, as measured by alternating current impedance spectroscopy and this is the case despite the fact that the polyfilm possesses nanosized columnar grains and thus an extremely high density of the grain boundaries. The highly conductive nature of grain boundaries in stabilized Bi2O3 is discussed in terms of the clean and chemically uniform grain boundary without segregates, and the implications for device application are suggested.
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Affiliation(s)
- Seung Jin Jeong
- Department of Materials Science and Engineering and ‡Graduate School of EEWS, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Korea
| | - No Woo Kwak
- Department of Materials Science and Engineering and ‡Graduate School of EEWS, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Korea
| | - Pilgyu Byeon
- Department of Materials Science and Engineering and ‡Graduate School of EEWS, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Korea
| | - Sung-Yoon Chung
- Department of Materials Science and Engineering and ‡Graduate School of EEWS, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Korea
| | - WooChul Jung
- Department of Materials Science and Engineering and ‡Graduate School of EEWS, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, Korea
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Bowman WJ, Kelly MN, Rohrer GS, Hernandez CA, Crozier PA. Enhanced ionic conductivity in electroceramics by nanoscale enrichment of grain boundaries with high solute concentration. NANOSCALE 2017; 9:17293-17302. [PMID: 29090719 DOI: 10.1039/c7nr06941c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The enhancement of oxygen ionic conductivity by over two orders of magnitude in an electroceramic oxide is explicitly shown to result from nanoscale enrichment of a grain boundary layer or complexion with high solute concentration. A series of CaxCe1-xO2-δ polycrystalline oxides with fluorite structure and varying nominal Ca2+ solute concentration elucidates how local grain boundary composition, rather than structural grain boundary character, primarily regulates ionic conductivity. A correlation between high grain boundary solute concentration above ∼40 mol%, and four orders of magnitude increase in grain boundary conductivity is explicitly shown. A correlated experimental approach provides unique insights into fundamental grain boundary science, and highlights how novel aspects of nanoscale grain boundary design may be employed to control ion transport properties in electroceramics.
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Affiliation(s)
- William J Bowman
- School for Engineering of Matter, Transport and Energy, Arizona State University, 501 E. Tyler Mall, Tempe, Arizona 85287-6106, USA.
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Tunable transport property of oxygen ion in metal oxide thin film: Impact of electrolyte orientation on conductivity. Sci Rep 2017; 7:3450. [PMID: 28615724 PMCID: PMC5471214 DOI: 10.1038/s41598-017-03705-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 05/05/2017] [Indexed: 11/08/2022] Open
Abstract
Quest for efficient ion conducting electrolyte thin film operating at intermediate temperature (~600 °C) holds promise for the real-world utilization of solid oxide fuel cells. Here, we report the correlation between mixed as well as preferentially oriented samarium doped cerium oxide electrolyte films fabricated by varying the substrate temperatures (100, 300 and 500 °C) over anode/ quartz by electron beam physical vapor deposition. Pole figure analysis of films deposited at 300 °C demonstrated a preferential (111) orientation in out-off plane direction, while a mixed orientation was observed at 100 and 500 °C. As per extended structural zone model, the growth mechanism of film differs with surface mobility of adatom. Preferential orientation resulted in higher ionic conductivity than the films with mixed orientation, demonstrating the role of growth on electrochemical properties. The superior ionic conductivity upon preferential orientation arises from the effective reduction of anisotropic nature and grain boundary density in highly oriented thin films in out-of-plane direction, which facilitates the hopping of oxygen ion at a lower activation energy. This unique feature of growing an oriented electrolyte over the anode material opens a new approach to solving the grain boundary limitation and makes it as a promising solution for efficient power generation.
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