Governing Principles in Hydration of Mixed Conducting Oxides (completed)

• Mielewczyk-Gryń, Aleksandra; Yang, Shuhao; Balaguer, Maria; Strandbakke, Ragnar; Sørby, Magnus Helgerud & Szpunar, Iga [Show all 11 contributors for this article] (2023). Energetics of formation and stability in high pressure steam of barium lanthanide cobaltite double perovskites. Dalton Transactions. ISSN 1477-9226. 52(17), p. 5771–5779. doi: 10.1039/d2dt03989c.
• Strandbakke, Ragnar; Wragg, David Stephen; Sørby, Magnus Helgerud; Guzik, Matylda; Gunnæs, Anette Eleonora & Szpunar, Iga [Show all 12 contributors for this article] (2022). Structural properties of mixed conductor Ba1−xGd1−yLax+yCo2O6−δ. Dalton Transactions. ISSN 1477-9226. 51(48), p. 18667–18677. doi: 10.1039/d2dt02277j. Full text in Research Archive Show summary

  Ba1−xGd1−yLax+yCo2O6−δ (BGLC) compositions with large compositional ranges of Ba, Gd, and La have been characterised with respect to phase compositions, structure, and thermal and chemical expansion. The results show a system with large compositional flexibility, enabling tuning of functional properties and thermal and chemical expansion. We show anisotropic chemical expansion and detailed refinements of emerging phases as La is substituted for Ba and Gd. The dominating phase is the double perovskite structure Pmmm, which is A-site ordered along the c-axes and with O vacancy ordering along the b-axis in the Ln-layer. Phases emerging when substituting La for Ba are orthorhombic Ba-deficient Pbnm and cubic LaCoO3-based R[3 with combining macron]c. When La is almost completely substituted for Gd, the material can be stabilised in Pmmm, or cubic Pm[3 with combining macron]m, depending on thermal and atmospheric history. We list thermal expansion coefficients for x = 0–0.3, y = 0.2.

• Wachowski, Sebastian Lech; Szpunar, Iga; Sørby, Magnus Helgerud; Mielewczyk-Gryń, Aleksandra; Balaguer, Maria & Ghica, Corneliu [Show all 12 contributors for this article] (2020). Structure and water uptake in BaLnCo2O6−δ (Ln = La, Pr, Nd, Sm, Gd, Tb and Dy). Acta Materialia. ISSN 1359-6454. 199, p. 297–310. doi: 10.1016/j.actamat.2020.08.018. Full text in Research Archive
• Szpunar, Iga; Strandbakke, Ragnar; Sørby, Magnus Helgerud; Wachowski, Sebastian Lech; Balaguer, Maria & Tarach, Mateusz [Show all 12 contributors for this article] (2020). High-temperature structural and electrical properties of BaLnCo2O6 positrodes. Materials. ISSN 1996-1944. 13(18), p. 1–18. doi: 10.3390/ma13184044. Full text in Research Archive
• Bjørheim, Tor Svendsen; Hoedl, Maximilian; Merkle, Rotraut; Kotomin, Eugene & Maier, Joachim (2020). Proton, Hydroxide Ion, and Oxide Ion Affinities of Closed-Shell Oxides: Importance for the Hydration Reaction and Correlation to Electronic Structure. Journal of Physical Chemistry C. ISSN 1932-7447. 124(2), p. 1277–1284. doi: 10.1021/acs.jpcc.9b07570.
• Andersen, Håkon; Xu, Kaiqi; Malyshkin, Dmitry; Strandbakke, Ragnar & Chatzitakis, Athanasios Eleftherios (2020). A highly efficient electrocatalyst based on double perovskite cobaltites with immense intrinsic catalytic activity for water oxidation. Chemical Communications. ISSN 1359-7345. 56(7), p. 1030–1033. doi: 10.1039/c9cc08765f.
• Szpunar, Iga; Wachowski, Sebastian; Miruszewski, Tadeusz; Dzierzgowski, Kacper; Górnicka, Karolina & Klimczuk, Tomasz [Show all 12 contributors for this article] (2019). Electric and magnetic properties of Lanthanum Barium Cobaltite. Journal of The American Ceramic Society. ISSN 0002-7820. 103(3), p. 1809–1818. doi: 10.1111/jace.16865. Full text in Research Archive
• Sun, Xinwei; Xu, Kaiqi; Fleischer, Christian; Liu, Xin; Grandcolas, Mathieu & Strandbakke, Ragnar [Show all 9 contributors for this article] (2018). Earth-abundant electrocatalysts in proton exchange membrane electrolyzers. Catalysts. ISSN 2073-4344. 8:657(12), p. 1–41. doi: 10.3390/catal8120657. Full text in Research Archive Show summary

  In order to adopt water electrolyzers as a main hydrogen production system, it is critical to develop inexpensive and earth-abundant catalysts. Currently, both half-reactions in water splitting depend heavily on noble metal catalysts. This review discusses the proton exchange membrane (PEM) water electrolysis (WE) and the progress in replacing the noble-metal catalysts with earth-abundant ones. The efforts within this field for the discovery of efficient and stable earth-abundant catalysts (EACs) have increased exponentially the last few years. The development of EACs for the oxygen evolution reaction (OER) in acidic media is particularly important, as the only stable and efficient catalysts until now are noble-metal oxides, such as IrOx and RuOx. On the hydrogen evolution reaction (HER) side, there is significant progress on EACs under acidic conditions, but there are very few reports of these EACs employed in full PEM WE cells. These two main issues are reviewed, and we conclude with prospects for innovation in EACs for the OER in acidic environments, as well as with a critical assessment of the few full PEM WE cells assembled with EACs.

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• Norby, Truls Eivind (2021). Electrode kinetics in fuel cells and electrolysers. Show summary

  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.

• Strandbakke, Ragnar; Bjørheim, Tor Svendsen; Sørby, Magnus Helgerud; Szpunar, Iga; Wachowski, Sebastian Lech & Mielewczyk-Gryń, Aleksandra [Show all 10 contributors for this article] (2020). Governing principles of hydration in mixed conducting oxides.
• Strandbakke, Ragnar; Bjørheim, Tor Svendsen; Sørby, Magnus Helgerud; Wachowski, Sebastian Lech; Mielewczyk-Gryn, Aleksandra & Balaguer, Maria [Show all 9 contributors for this article] (2019). Hydration and hydrogenation of mixed conducting BaGd1‑xLaxCo2O6‑δ (BGLC).
• Strandbakke, Ragnar; Balaguer, Maria; Wachowski, Sebastian Lech; Mielewczyk-Gryn, Aleksandra; Almeida Carvalho, Patricia & Sørby, Magnus Helgerud [Show all 7 contributors for this article] (2019). Protonics, stability and electrochemistry of Ba1‑xGd1-yLax+yCo2O6-δ (BGLC).
• Strandbakke, Ragnar; Bjørheim, Tor Svendsen; Vøllestad, Einar; Mielewczyk-Gryn, Aleksandra; Wachowski, Sebastian Lech & Lewandowska, Iga [Show all 9 contributors for this article] (2019). Defect chemistry of mixed conducting double perovskites .
• Vøllestad, Einar; Sørby, Magnus Helgerud & Norby, Truls Eivind (2019). Defect chemistry of mixed conducting double perovskites .
• Strandbakke, Ragnar; Vøllestad, Einar; Sørby, Magnus Helgerud & Norby, Truls Eivind (2019). Defect chemistry of mixed conducting double perovskites .
• Strandbakke, Ragnar; Bjørheim, Tor Svendsen; Sørby, Magnus Helgerud; Szpunar, Iga; Wachowski, Sebastian Lech & Mielewczyk-Gryn, Aleksandra [Show all 9 contributors for this article] (2019). Protons in mixed conducting Ba1‑xGd1‑yLax+yCo2O6‑δ (BGLC).
• Norby, Truls Eivind (2019). Water and protonic conduction on surfaces of nanomaterials - role in catalytic processes. Show summary

  Water vapour chemisorbs on surfaces as protons and hydroxide ions at elevated temperatures and physisorbs as molecular water at lower temperatures in ice-like thin and liquid-like thick layers, respectively. Also hydrogen adsorbs and dissociates. All adsorbates give rise to surface protonic conduction of different mechanisms and magnitude depending on temperature and acidity of the surface. The surface protonic conduction may be used in electrolytes for electrochemical cells, but in this talk focus is more on its effect in some catalytic processes in finely porous nanomaterials.

• Bjørheim, Tor Svendsen; Maier, Joachim; Merkle, Rotraut; Kotomin, Eugene & Hoedl, Maximillian (2019). Defect thermodynamics and lattice site basicity of proton and mixed conducting oxides, .
• Norby, Truls Eivind (2018). The chemistries of proton ceramic electrochemical cells.
• Bjørheim, Tor Svendsen; Hoedl, Maximillian; Kotomin, Eugene; Merkle, Rotraut & Maier, Joachim (2018). Hydration thermodynamics and lattice site basicity of proton conducting and mixed conducting oxides .
• Strandbakke, Ragnar; Gunnæs, Anette Eleonora; Carvalho, Patricia A.; Mielewczyk-Gryn, Aleksandra; Wachowski, Sebastian & Balaguer, Maria [Show all 8 contributors for this article] (2018). Coupled hydration, cation reorganization and red-ox in MIEC perovskites .
• Wachowski, Sebastian; Levandowska, Iga; Sørby, Magnus Helgerud; Balaguer, Maria; Bjørheim, Tor Svendsen & Gazda, Maria [Show all 10 contributors for this article] (2018). Governing Principles in Hydration of Mixed Conducting Oxides: Structure and Hydration of BaLnCo2O6-d.
• Balaguer, Maria; Tarach, Mateusz; Strandbakke, Ragnar; Bjørheim, Tor Svendsen; Mielewczyk-Gryn, Aleksandra & Wachowski, Sebastian [Show all 11 contributors for this article] (2018). Hydration Stability of Mixed Conducting Layered Oxides .
• Strandbakke, Ragnar; Bjørheim, Tor Svendsen; Mielewczyk-Gryn, Aleksandra; Wachowski, Sebastian; Lewandowska, Iga & Balaguer, Maria [Show all 10 contributors for this article] (2018). Governing Principles in Hydration of Mixed Conducting Oxides.
• Norby, Truls Eivind (2018). Electrodics for proton ceramic electrochemical cells (PCECs).
• Strandbakke, Ragnar; Vøllestad, Einar; Norby, Truls Eivind; Sartori, Sabrina; Guzik, Matylda Natalia & Lang, Julien (2017). Hydration and structural properties of mixed conductor Ba1‑xGd0.8La0.2+xCo2O6-δ (BGLC).

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