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Wang, Luyang; Sun, Xinwei; Jiang, Bo & Norby, Truls
(2024).
Minority bulk and surface proton conduction in ceramic positrodes for proton ceramic electrochemical cells.
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Sun, Xinwei & Norby, Truls
(2024).
Charge and mass transfer polarisation of BGLC37 positrodes for proton ceramic electrochemical cells.
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Norby, Truls
(2024).
Mechanisms and polarisation of electrodes for proton ceramic electrochemical cells (PCECs).
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Roen, Stine; Norby, Truls; Strandbakke, Ragnar & Polfus, Jonathan M.
(2023).
Electrochemical characterization of Ba0.95La0.05(Fe0.7Ni0.2Zn0.1)O3-δ for proton ceramic electrochemical cells.
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Tirados, Irene Yuse; Kjølseth, Christian & Norby, Truls
(2023).
Understanding the Impedance Puzzle: Analyzing Behavior under Bias of Ni-BZCY Cells for Proton Ceramic Electrochemical Reactor Stacks
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Ewerhardt, Patrick; Wu, Mengxin; Norby, Truls; Bjørheim, Tor Svendsen & Polfus, Jonathan M.
(2023).
Finite element modelling of kinetic processes in proton ceramic electrochemical cells.
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Wang, Luyang; Sun, Xinwei & Norby, Truls
(2023).
Minority Bulk and Surface Proton Conduction in Positrodes for Proton Ceramic Electrochemical Cells.
Vis sammendrag
The positrode is a critical component for proton ceramic steam electrolyzers and fuel cells for hydrogen and ammonia. It constitutes a major contribution to the over-potentials and hence losses in the whole cell, resulting from its limited solubility and diffusivity of protons, which is challenging to characterise and improve.
We are introducing a PhD project that aims to establish theoretical frameworks and experimental methodology for measuring protonic conductivities in the bulk and on surfaces of positrode materials. The approaches to reach the goal comprise the use of defect chemistry and transport theory for protons conduction, with the implementation of physiochemical experiments to distinguish signals of protons among other defects and charge carriers and paths on those predominantly electronic conductors. The results will be used as input to other project participants who perform computer simulations and, on that basis, seek strategies for optimization and effects on electrodes in scaled-up cells.
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Norby, Truls
(2023).
Proton Conducting Ceramics - Science and Applications
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Norby, Truls
(2023).
Protons in Solids From Young Discovery to Clean Hydrogen Technology
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Norby, Truls
(2023).
Transport in electrolytes and electrodes of proton ceramic electrochemical cells (PCECs)
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Norby, Truls
(2023).
Mechanisms and parameterization of electrodes for proton ceramic electrochemical cells.
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Norby, Truls
(2023).
Thermodynamics and polarisation of electrodes for proton ceramic electrochemical cells.
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Norby, Truls
(2023).
Solar hydrogen from adsorbed water vapour in all-solid photoelectrochemical cells.
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Norby, Truls
(2023).
Nomenclature and transport of defects in surface protonics.
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Strandbakke, Ragnar; Singh, Kalpana & Norby, Truls
(2022).
Effect of partial conductivities on the polarisation resistance of positrodes for proton ceramic fuel cells and electrolysers.
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Singh, Kalpana; Norby, Truls & Strandbakke, Ragnar
(2022).
Effect of partial conductivities on the polarisation resistance of positrodes for proton ceramic fuel cells and electrolysers.
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Chatzitakis, Athanasios; Zhu, Junjie; Gudmundsdottir, Jonina Björg; Strandbakke, Ragnar; Both, Kevin Gregor & Aarholt, Thomas
[Vis alle 12 forfattere av denne artikkelen]
(2022).
A monolithic and noble metal-free photoelectrochemical device of minimal engineering for efficient, unassisted water splitting.
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Kang, Xiaolan; Reinertsen, Vilde Mari; Both, Kevin Gregor; Galeckas, Augustinas; Aarholt, Thomas & Prytz, Øystein
[Vis alle 9 forfattere av denne artikkelen]
(2022).
Exsolved nanoparticles, galvanically restructured for tunable photo-electrocatalytic energy conversion.
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Kang, Xiaolan; Chaperman, Larissa; Galeckas, Augustinas; Ammar-Merah, Souad; Mammeri, Fayna & Norby, Truls
[Vis alle 7 forfattere av denne artikkelen]
(2022).
Water Vapor Photoelectrolysis in an All Solid-State Photoelectrochemical Cell
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Both, Kevin Gregor; Reinertsen, Vilde Mari; Kang, Xiaolan; Neagu, Dragos; Prytz, Øystein & Norby, Truls
[Vis alle 7 forfattere av denne artikkelen]
(2022).
Thin Film Exsolution of Metal Nanoparticles and Their Galvanic Restructuring for Plasmonically Enhanced Photocatalytic Activity.
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Both, Kevin Gregor; Reinertsen, Vilde Mari; Kang, Xiaolan; Aarholt, Thomas; Neagu, Dragos & Prytz, Øystein
[Vis alle 8 forfattere av denne artikkelen]
(2022).
Improved Photoelectrochemical Performance of SrTiO3 by Plasmonically Active Au Nanoparticles.
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Clark, Daniel Ryan; Malerød-Fjeld, Harald; Budd, Michael; Yuste Tirados, Irene; Beeaff, Dustin R. & Aamodt, Simen
[Vis alle 17 forfattere av denne artikkelen]
(2022).
Proton ceramic electrochemical reactors for sustainable hydrogen production.
Vis sammendrag
Electrochemical gas separation emerges as an attractive technology as the cost of electricity declines. Proton ceramic electrochemical reactors (PCERs) extract hydrogen from reaction mixtures and can offer a compact and efficient approach to hydrogen production [1]. Because of the solid-state and gas-impermeable nature of the membrane, the hydrogen produced can in principle be entirely free of impurities, as unreacted molecules cannot get to the other side of the membrane. Through a one-step process, balancing the energy from the endothermic reactions with the separation and compression of hydrogen allows for much higher efficiencies compared with other hydrogen production technologies. In the case of CH4 reforming, the possibility of extracting H2 at conditions suitable for the reforming reaction enables the overcome of the thermodynamic limitations in terms of CH4 conversion. Furthermore, the electrochemical H2 compression allows to go beyond the driving force limitation of traditional membrane reactors (based for example on Pd membranes). PCERs offer attractive performance including mechanical stability and chemical robustness over a wide range of temperatures (300–800 °C) and pressure conditions (> 50 bar).
In our recent work [2], we demonstrate the upscaling of an efficient 36 cell x 15 cm2 reactor with coupled heat, reaction and current distribution. Hydrogen extraction > 99 % shows complete conversion of CH4 for conditions relevant both for natural gas and biogas, and a hydrogen purity up to 99.995 %. The by-product leaving the reactor is a concentrated CO2 stream, which can facilitate the implementation of efficient carbon capture. The results suggests that proton ceramic electrochemical reactors can offer the lowest CO2 intensity for on-site hydrogen production. Furthrmore, to expand on the wide applicability and flexibility of the proposed technology, cell performance for ammonia decomposition will be presented, showing similar conversion with both anhydrous and aqueous NH3.
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Balaguer, Maria; Wachowski, Sebastian Lech; Szpunar, Iga; Mielewczyk-Gryn, Aleksandra; Sørby, Magnus Helgerud & Carvalho, Patricia A.
[Vis alle 10 forfattere av denne artikkelen]
(2022).
Double perovskite mixed conductors – Hydration, red-ox, structure and stability.
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Clark, Daniel Ryan; Malerød-Fjeld, Harald; Budd, Michael; Yuste Tirados, Irene; Beeaff, Dustin R. & Aamodt, Simen
[Vis alle 17 forfattere av denne artikkelen]
(2022).
Proton ceramic electrochemical reactors for sustainable hydrogen production.
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Stange, Marit Synnøve Sæverud; Denonville, Christelle; Stefan, Elena; Dayaghi, Amir Masoud; Larring, Yngve & Rørvik, Per Martin
[Vis alle 9 forfattere av denne artikkelen]
(2022).
Fabrication and testing of thin-film based metal-supported proton ceramic electrochemical cells.
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Dayaghi, Amir Masoud; Polfus, Jonathan; Strandbakke, Ragnar; Vøllestad, Einar; Haugsrud, Reidar & Norby, Truls
(2022).
Effects of NiO, ZnO and CuO sintering additives on the hydration of BaZr0.4Ce0.4(Y,Yb)0.2O3-δ proton conducting electrolytes.
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Kang, Xiaolan; Reinertsen, Vilde Mari; Both, Kevin Gregor; Galeckas, Augustinas; Aarholt, Thomas & Prytz, Øystein
[Vis alle 9 forfattere av denne artikkelen]
(2022).
Galvanic Restructuring of Exsolved Nanoparticles for Plasmonic and Electrocatalytic Energy Conversion (Small 29/2022 Inside back cover feature).
Small.
ISSN 1613-6810.
18(29).
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Norby, Truls; Karsthof, Robert Michael; Saeed, Sarmad Waheed; Kuznetsov, Andrej & Vines, Lasse
(2022).
The p-n junction has nothing to do with ionics. Does it?
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Sun, Xinwei; Vøllestad, Einar & Norby, Truls
(2022).
Surface protonic conductivity in chemisorbed and physisorbed water layers in porous nanoscopic CeO2
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Kang, Xiaolan; Reinertsen, Vilde Mari; Both, Kevin Gregor; Galeckas, Augustinas; Aarholt, Thomas & Prytz, Øystein
[Vis alle 9 forfattere av denne artikkelen]
(2022).
Galvanic restructuring of exsolved nanoparticles for plasmonic and electrocatalytic energy conversion
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Pedersen, Madeeha Khalid & Norby, Truls
(2022).
Defect Models for Li-Ion Transport in Al- and Nb-Doped LLZO.
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Norby, Truls
(2022).
Defects and transport in inherently disordered oxide structures
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Sun, Xinwei; Vøllestad, Einar & Norby, Truls
(2022).
Surface protonics - a tutorial.
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Norby, Truls
(2022).
Defects and transport in proton conducting ceramics for energy applications.
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Norby, Truls; Ma, Quanbao; Qureishy, Thomas & Uggerud, Einar
(2022).
Plasma-enhanced ammonia synthesis over nanoscopic Ru/CeO2.
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Norby, Truls
(2022).
Geometrical aspects of surface protonics.
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Norby, Truls
(2022).
Chemistry of high-temperature thermoelectric oxides and TEGs
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Norby, Truls
(2022).
Proton ceramics for energy applications.
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Xing, Wen; Peters, Thijs; Fontaine, Marie-Laure; Norby, Truls & Bredesen, Rune
(2021).
Inorganic membranes for gas separation: opportunities and challenges.
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Stange, Marit Synnøve Sæverud; Stefan, Elena; Dayaghi, Amir Masoud; Denonville, Christelle; Larring, Yngve & Rørvik, Per Martin
[Vis alle 8 forfattere av denne artikkelen]
(2021).
Pulsed Laser Deposition of Electrolytes for Metal-Supported Proton-Conducting Electrolysis Cells.
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Norby, Truls
(2021).
New ways for protons and electrons in functional materials .
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Norby, Truls
(2021).
Surface protonics and its roles in synthesis and use of ammonia.
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Norby, Truls
(2021).
Proton ceramics - a tutorial.
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Norby, Truls; Dayaghi, Amir Masoud; Storhaug, Sjur; Chen, Henry; Haugsrud, Reidar & Stange, Marit Synnøve Sæverud
[Vis alle 9 forfattere av denne artikkelen]
(2021).
BSZCY151020: A proton ceramic electrolyte with increased TEC for planar applications
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Øygarden, Vegar; Mahmood, Asif; Vøllestad, Einar; Denonville, Christelle; Norby, Truls & Rørvik, Per Martin
(2021).
Development of electrochemical cells based on surface protonics.
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Øygarden, Vegar; Mahmood, Asif; Vøllestad, Einar; Denonville, Christelle; Norby, Truls & Rørvik, Per Martin
(2021).
Development of electrodes and complete electrochemical cells based on surface protonics.
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Sun, Xinwei & Norby, Truls
(2021).
Surface protonic conductivity in chemisorbed and physisorbed water layers in porous nanoscopic CeO2.
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Stange, Marit Synnøve Sæverud; Stefan, Elena; Denonville, Christelle; Dayaghi, Amir Masoud; Larring, Yngve & Rørvik, Per Martin
[Vis alle 11 forfattere av denne artikkelen]
(2021).
Processing route for Metal Supported Proton Conducting Ceramic Cells.
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Norby, Truls; Kang, Xiaolan; Sun, Xinwei; Vøllestad, Einar; Gu, Jie & Han, Donglin
(2021).
Surface Protonics of Porous Oxide Ceramics.
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Øygarden, Vegar; Vøllestad, Einar; Denonville, Christelle; Vistad, Ørnulv Bjørnsson; Mahmood, Asif & Norby, Truls
[Vis alle 7 forfattere av denne artikkelen]
(2021).
Development of electrodes and complete electrochemical cells based on surface protonics.
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Strandbakke, Ragnar; Balaguer, María; Carrillo, Alfonso; Wachowski, Sebastian Lech; Mielewczyk-Gryń, Aleksandra & Szpunar, Iga
[Vis alle 13 forfattere av denne artikkelen]
(2021).
Hydration and electrochemistry of mixed conducting cobaltites.
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Strandbakke, Ragnar; Balaguer, María; Carrillo, Alfonso; Wachowski, Sebastian Lech; Mielewczyk-Gryń, Aleksandra & Szpunar, Iga
[Vis alle 14 forfattere av denne artikkelen]
(2021).
Hydration and electrochemistry of mixed conducting cobaltites.
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Norby, Truls; Sun, Xinwei; Kang, Xiaolan; Vøllestad, Einar; Gu, Jie & Han, Donglin
(2021).
Surface Protonics of Porous Oxide Ceramics .
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Norby, Truls
(2021).
Electrode kinetics in fuel cells and electrolyzers.
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Norby, Truls Eivind
(2021).
Electrode kinetics in fuel cells and electrolysers.
Vis sammendrag
Fuel cells constitute the technology of choice to convert hydrogen to electricity, while electrolyzers will be a major technology for producing that hydrogen from electricity from renewable sources, notably indirect (hydroelectric, wind, wave) and direct (photovoltaic) solar energy. They are hence not directly the topic of a workshop on solar fuels, but photoelectrochemical (PEC) electrode kinetics is such a complex matter that it is useful to have electrode kinetics of fuel cells and electrolyzers as kind of reference.
Both PEC and fuel cells and electrolyzers have in common that established state-of-the-art versions have aqueous liquid electrolytes, while solid-state electrolytes are of increasing interest. We will cover both, and dwell on various intermediate cases. While various charge carrying ions are in use in different ranges of temperature (O2-, CO32-, H+, OH-, H3O+), protonic electrolytes are most central to PEC and we will focus on them, with examples from proton ceramics, proton exchange membranes (PEMs), hydroxide ion conducting polymers, and surface protonic conduction.
The electrode reaction comprises faradaic charge transfer over the electrolyte-electrode interface. This can be an electron transfer (redox) or – in the case of mixed ion electron conducting electrodes – ion transfer, in which case the electron transfer must take place somewhere else, e.g. on the electrode surface. The charge transfer – which is our means of driving the reaction with a voltage or recording a current in a chemically driven fuel cell – may be hindered by the supply of reactants, making adsorption and dissociation appear in the polarization resistance. In addition, diffusion in gas phase, over surfaces, and in the bulk of the electrode or electrolyte slows the reaction further and may eventually limit the current.
While charge transfer takes place over the double layer capacitance of the electrolyte-electrode interface, the other processes may store reactants and products as much higher chemical capacitance, whereby the different processes have different time constants and may be separated in impedance spectroscopy.
The talk will go through materials, processes, and methods, look to general principles that can be applied across systems and technologies, where possible also photoelectrochemical cells for solar hydrogen and artificial photosynthesis.
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Norby, Truls Eivind
(2021).
Fra forsker til grunder: Hvilken hjelp skulle jeg ønsket meg.
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Both, Kevin Gregor; Chatzitakis, Athanasios; Bergum, Kristin; Hansen, Per-Anders Stensby; Prytz, Øystein & Norby, Truls
(2023).
Plasmonically Enhanced Photocatalysis: Synthesis, Physical Properties, and Applications.
University of Oslo Livrary.
ISSN 1501-7710.
Fulltekst i vitenarkiv
Vis sammendrag
In this work, plasmonic metal nanoparticles (MNPs) are utilized to improve the photoelectrochemical (PEC) response of strontium titanate (STO). These MNPs were introduced by either direct exsolution, i.e., nickel (Ni), copper (Cu), iron (Fe), ruthenium (Ru), and silver (Ag), or by galvanically replacing exsolved less noble MNPs, i.e., Ni by Gold (Au), or Cu for Ag. Au, Ag, and Cu were the materials chosen with significant plasmonic activity; Fe, Ru, Pt, and Ni were used to make MNPs with minimal plasmonic response.
Two different stoichiometries of STO were synthesized. One, La-doped A-site deficient STO (La0.6Sr0.2Ti0.9Ni0.1O3–x), was exclusively doped with Ni and utilized as powder samples. The other stoichiometry was A-site excess STO (Sr1.07Ti0.93M0.07O3±δ, where M is the dopant) was doped with various metals. These excess perovskites were studied in thin film and powder forms.
A-site excess STO thin films were deposited by pulsed laser deposition on silicon substrates. The as-deposited thin films appeared nanocrystalline or amorphous until the exsolution process was engaged. The exsolution step was studied explicitly for these A-site excess STO thin films where the formation of MNPs occurred not only at or near the thin film surface but also on grain interfaces and in bulk. Moreover, the dopant diffused significantly during the process.
While the size of the template particles depended on the exsolution conditions, the galvanic replacement reaction determined the shapes and sizes of the newly formed MNPs. The replacement time and the form (thin film/powder) of STO influenced the results, both completely replaced particles and partially replaced particles with complex structures were obtained. Additionally, more prolonged galvanic replacement reactions lead to larger particles. In turn, the specific shape of the plasmonic MNPs determined the localized surface plasmon resonance band shape and peak position.
Overall, exsolution leads to well-socketed MNPs, a property seemingly inherited by the MNPs created by galvanic replacement. Well-socketed MNPs are extremely difficult to obtain by any other technique and have a favorable localized surface plasmon resonance peak shift. The PEC response revealed that reducing STO first decreases the material’s response. Reducing it further, however, increases the PEC response significantly. Au MNPs increase the PEC performance until the MNPs reach a specific size and subsequently decrease the PEC performance when growing more prominent. This work highlights the ease by which well-socketed plasmonic MNPs can be created, some impossible to synthesize by another technique, and how different reaction conditions can change the shape and size of the MNPs, ultimately tuning the localized surface plasmon resonance band shape and peak position. The method of exsolution and galvanic replacement reaction was generalized by utilizing different elements, implying that the tuning of catalytic activity depends on the choice of elements and reaction conditions.
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Storhaug, Sjur; Haugsrud, Reidar & Norby, Truls
(2022).
Sintering and electrical properties of proton conducting BSZCY151020.
Universitetet i Oslo.
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Svee, Tord; Norby, Truls; Haugsrud, Reidar; Strandbakke, Ragnar; Thoreton, Vincent & Clar, Daniel
(2021).
Surface kinetics of BaGd1-xLaxCo2O6-𝛿 for use as an anode material in proton ceramic electrolyser cells.
Universitetet i Oslo.
Vis sammendrag
The main topic of this thesis is the surface kinetics of BaGdxLa1-xCo2O6-δ (BGLC), a mixed ionic electronic conducting double perovskite, with operation temperatures between 400-700 °C that shows potential for use as an anode in Proton Conducting Ceramic Electrolysers (PCEC). While showing promise the material is still limited by its surface reactions, notably adsorption and dissociation. To test the variation in surface kinetics with the ratio of lanthanides on the A’-site, five compositions with differing lanthanide content was synthesised with a sol-gel synthesis path: BGLC19 (BaGd0.1La0.9Co2O6-δ), BGLC37 (BaGd0.3La0.7Co2O6-δ), BGLC55 (BaGd0.5La0.5Co2O6-δ), BGLC73 (BaGd0.7La0.3Co2O6-δ) and BGLC91 (BaGd0.9La0.1Co2O6-δ). Acceptable phase purity was determined through X-ray diffractometry (XRD), the batches sieved into four different grain size ranges, with diameters of 63-45 μm being used for all later experiments. Scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) analysis were applied to examine the morphology and determine the specific surface area of the samples. Pulse isotope exchange (PIE) and gas phase analysis (GPA) were used to examine the surface kinetics of the samples. The PIE data also allows us to extract the adsorption and incorporation energy of gas species from the total activation energy. Comparative measurements in 21% oxygen at 400 °C for BGLC19 with GPA and PIE resulted in surface exchange coefficients for oxygen of 6.8×10-5 mol m-2 s -1 (PIE) and 1.3×10-5 mol m-2 s -1 (GPA), with the difference being attributed to exchange rates in GPA being limited by gas diffusion in the chamber. An experiment was also performed with PIE on BGLC19 in 21% and 2% oxygen, resulting in surface exchange coefficients of 6.8×10-5 mol m-2 s -1 (21%) and 1.2×10-4 mol m-2 s -1 (2%) at 400 °C. The total activation energy E0 for oxygen exchange was lower in 2% oxygen (0.84 eV in 2% vs 1.1 eV in 21%), but with a slightly higher adsorption energy Eads (0.79 eV in 2% vs 0.62 eV in 21%). Measurements were also performed with PIE in 2% oxygen across compositions, with BGLC55 showing the lowest incorporation energy Einc for oxygen at 0.82 eV but with the highest E0 (0.91 eV) and Eads (0.92 eV) of the set. BGLC73 displayed the lowest values for total activation and adsorption energies at 0.62 eV (E0) and 0.69 eV (Eads). The highest surface exchange rates for oxygen were measured for BGLC19, BGLC73 and BGLC91 at over 1×10-4 mol m-2 s -1 , while the values for BGLC37 and BGLC55 were around 6×10-4 mol m-2 s -1 . 3 PIE experiments involving the exchange of water vapour were also performed on BGLC37 and BGLC91, with BGLC73 exchanging the most water up to 450 °C. With unclear data and very little to no D2O measured by the mass spectrometer, these experiments remain inconclusive.
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Alsgaard, Erik Erlend Pham; Norby, Truls; Haugsrud, Reidar & Bjørheim, Tor Svendsen
(2021).
Protonic Transport Properties of Perovskite Heterostructures.
Universitetet i Oslo.
Vis sammendrag
Proton ceramic fuel cells based on an yttrium-doped barium zirconate electrolyte might pose as a viable option for future hydrogen applications. High resistances in the electrolyte however hampers the performance of the material. Therefore, a novel heterostructure engineering strategy is applied in order to investigate alternative solutions to reducing the resistances. This thesis aims to deepen our understanding of how heterostructures and their interfaces might affect the electrolyte resistances. The goal of the following approach is to circumvent proton trapping at acceptor dopant sites. A job-sharing model has been investigated where one phase “supplies” the protons while the other phase conducts them. The proton donor phase is acceptor doped and more acidic than the other phase, resulting in a net transfer of protons over to the conductive phase. The latter phase, free of trap sites and enriched in charge carriers, is then hypothesized to exhibit a conductivity increase. Modern computational methods allow for compositions to be investigated theoretically without having to perform tedious experiments. While experiments measure the actual effects of the system of interest, the results might be ambiguous as they often are a combination of several contributions. Theoretical computations on the other hand might give insight into trends, often on the atomistic scale, else impossible to separate from other effects experimentally. Combining the two methods, in depth knowledge and understanding of the system is acquirable. The model system, an alternating multi layered BaZr1-xYxO3/SrTi1-xScxO3 film was fabricated by pulsed laser deposition onto a (100) MgO substrate. The thin (60 nm) films were by X-ray diffraction confirmed to be grown epitaxially, made possible by a good lattice match between the substrate and the films. Impedance spectroscopy measurements of the BaZrO3/SrTi0.9Sc0.1O3 film showed a conductivity of 0.27 mS/cm, comparable to the conductivity of the reference BaZr0.9Y0.1O3 film (0.28 mS/cm). The activation energy of the heterostructure was measured to 0.45 eV, lower than for the reference BaZrO3 and BaZr0.9Y0.1O3 films and in the range of the proton migration activation energy. The SrTi0.9Sc0.1O3 had a larger activation energy of 0.64 eV, expected for oxide ion conduction mechanism. VII When going to dry from humid atmosphere for the BaZr1-xYxO3 containing films was a decrease in conductivity of 55 % to 65 %, attributed to a decrease in charge carrier (proton) concentrations which was further confirmed by a hydrogen isotope exchange. A slope of 0.143 was observed in the Arrhenius plot of the SrTi0.9Sc0.1O3 film, indicating that ionic defects dominate concentration-wise whilst minority holes contribute significantly to the conductivity in the measured pO2 range. First principles calculations of a BaZr0.984Y0.016O3H0.016 4 by 4 supercell showed the energy difference a at set of Y-H + distances. The trapping energy of the protons was calculated as a function of in-plane strain and was found to increase with more negative (compressive) strain. Additionally, strain in general decreases the long-range mobility of protons in the yttrium dopants because of an energy barrier, larger than or equal to the trapping energy. Removing -0.5 % of strain was found to result in an activation energy decrease, increasing the conductivity by a factor of two. The calculated trapping energy change for different levels of strain agree well with experimental activation energies from literature [1]. Comparisons of measurements between reference films and the BaZrO3/SrTi0.9Sc0.1O3 heterostructure supports the job-sharing model. By assuming that the space charge region of the BaZrO3 and SrTi0.9Sc0.1O3 does not affect the conductivity of the latter, a conductivity increase of a factor of 14 was calculated for the BaZrO3 layer of the heterostructure compared to the reference BaZrO3 film.
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Kang, Xiaolan; Norby, Truls & Chatzitakis, Athanasios
(2021).
Novel nanostructured materials for energy applications.
Universitetet i Oslo, Det matematisk-naturvitenskapelige fakultet.
ISSN 1501-7710.
2021(2465).
Vis sammendrag
Nanomaterials and nanotechnology have been flourishing greatly over the last decades and their applications are spreading almost over all the branches of science and technology. In this work, we zoomed into the synthesis and characterization of nanostructured materials. The central focus was to manipulate the compositions, morphology and structures of nanomaterials by combining various strategies like defect engineering and exsolution. Several interesting features and properties of nanostructured materials were investigated and highlighted, including the optical, plasmonic, electronic and surface properties. This process deepened our fundamental understanding of surface protonic conduction of nanocrystalline oxides and increased our control over nanostructuring of materials in order to achieve targeted functionalities. The as-prepared nanomaterials have been applied in energy- and environment-related applications, showing improved and controllable efficiency in pollutants degradation and water (vapor) splitting in photocatalytic, (photo) electrocatalytic, as well as in a solid-state photoelectrocatalytic systems.
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Kalland, Liv-Elisif Queseth; Norby, Truls Eivind; Mohn, Chris Erik & Haugsrud, Reidar
(2021).
Ab-initio modelling and experimental study of order-disorder, hydration, and ionic conductivity of fluorite-related oxides.
Matematisk Naturvitenskapelig fakultet, Universitetet i Oslo.
ISSN 1501-7710.
2021(2348).
Vis sammendrag
Hydrogen will play a key role in a zero-emission society, and proton (H+) conducting oxides have gained interest as solid-state electrolytes for next-generation electrochemical devices for fuel cells and electrolyzers. Understanding the effect of structure on materials functional properties is important for enhancing the performance of such electrolytes. Oxides with fluorite related crystal structures are interesting for their high oxide ion and proton (H+) conductivities, and in this work the relationship between the atomic structure and the materials properties such as ionic conductivity and hydration properties have been studied for three different oxides. They are oxygen deficient with respect to the fluorite structure and the vacant oxide ion sites can thus be ordered or disordered. Through a combination of different experimental and computational methods the nature and degree of ordering and the atomic structure have been determined, and correlated to the properties of the cations present, such as size and electronegativity. The work further focuses on whether ordering the oxide ion vacancies affects the hydration and consequently the proton conductivity. The results have led us to propose a new model for hydration of heavily doped yet disordered fluorite oxides.
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Schuler, Raphael; Fjellvåg, Helmer & Norby, Truls Eivind
(2021).
Oxide thermoelectrics - materials, junctions and modules.
Matematisk Naturvitenskapelig fakultet, Universitetet i Oslo.
ISSN 1501-7710.
2021(2364).
Vis sammendrag
Thermoelectric materials are able to directly convert heat into electricity, which makes them predestined candidates for the recuperation of waste heat and contributing to a more efficient energy economy. They hold enormous potential for energy generation, since all thermodynamic processes lose a major portion of their energy in the form of waste heat.
However, conventional thermoelectric materials are often toxic, scarce and/or expensive, and show limited high temperature stability, which currently limits their relevance for large-scale applications. Recently, oxide thermoelectric materials, composed of abundant elements have attracted increased interest, as they offer a cheaper, environmental-friendly, and high-temperature stable alternative. They are usually discovered and researched individually, and only later combined to a p-n pair in a module, which often leads to complications, like thermal mismatch or reactions.
In this work the approach was taken to design a compatible pair of new thermoelectric oxides that preclude complications in advance. This novel approach is demonstrated on a model pair of iron tungstates, which show promising thermoelectric properties and an exceptional band alignment, which could prove to be key properties for future thermoelectrics.