Truls Norby

• Desissa, Temesgen D.; Haugsrud, Reidar; Wiik, Kjell & Norby, Truls Eivind (2018). Inter-diffusion across a direct p-n heterojunction of Li-doped NiO and Al-doped ZnO. Solid State Ionics.  ISSN 0167-2738.  320, s 215- 220 . doi: https://doi.org/10.1016/j.ssi.2018.03.011 Vis sammendrag

  We herein report inter-diffusion across the interface between p-type Ni0.98Li0.02O and n-type Zn0.98Al0.02O for various applications including p-n-heterojunction diodes and oxide thermoelectrics. Diffusion couples were made of polished surfaces of ceramic samples pre-sintered at 1250 and 1350 °C for Ni0.98Li0.02O and Zn0.98Al0.02O, respectively. The inter-diffusion couples were annealed at 900–1200 °C for 160 h in ambient air. Electron Probe Micro Analysis (EPMA) was used to acquire diffusion profiles, followed by fitting to Fick's second law and Whipple–Le Claire's models for bulk and grain-boundary diffusion calculation, respectively. Zn2+ diffused into Ni0.98Li0.02O mainly by bulk diffusion with an activation energy of 250 ± 10 kJ/mol, whereas Ni2+ diffused into Zn0.98Al0.02O by both bulk and enhanced grain boundary diffusion with activation energies of 320 ± 120 kJ/mol and 245 ± 50 kJ/mol, respectively. The amount of Al3+ diffused from the Al-doped ZnO into the NiO phase was too small for a corresponding diffusion coefficient to be calculated. Li-ion distribution and diffusivity were not determined due to lack of analyzer sensitivity for Li. The bulk and effective diffusivities of Zn2+ and Ni2+ into NiO and ZnO enable prediction of inter-diffusion lengths as a function of time and temperature, allowing estimates of device performance, stability, and lifetimes at different operation temperatures.

• Desissa, Temesgen D.; Kanas, Nikola; Singh, Sathya Prakash; Wiik, Kjell; Einarsrud, Mari-Ann & Norby, Truls Eivind (2018). Chemical tracer diffusion of Sr and Co in polycrystalline Ca-deficient CaMnO3-δ with CaMn2O4 precipitates. Physical Chemistry, Chemical Physics - PCCP.  ISSN 1463-9076. . doi: 10.1039/C7CP07471A Vis sammendrag

  Diffusivity on the A- and B-site of polycrystalline perovskite CaMnO3-δ with Ca deficiency and spinel CaMn2O4 (marokite) as a secondary phase was studied using chemical tracers and secondary ion mass spectrometry (SIMS) complemented by electron probe microanalysis (EPMA). Thin films containing Sr and Co chemical tracers were deposited on the polished surface of the polycrystalline composite sample followed by annealing at 800 – 1200 °C for 96 h. Diffusion profiles for each tracer were determined with SIMS, followed by calculation of diffusion coefficients by fitting to appropriate models. The Sr tracer showed mainly lattice diffusion, with an activation energy of 210±30 kJ/mol, whereas the Co tracer showed a combination of lattice and enhanced grain-boundary diffusion, with activation energies of 270±30 kJ/mol and 380±40 kJ/mol, respectively. The diffusivities may be used to predict interdiffusion and lifetime of junctions between n-type CaMnO3-δ or CaMnO3-δ/CaMn2O4 composites and metallization interlayers or p-type leg materials in oxide thermoelectrics. In particular, the relatively high effective diffusivity of Co in polycrystalline CaMnO3 δ may play a role in the reported fast formation of the secondary phase (Ca3Co2-yMnyO6) between p-type Ca3Co3.92O9+δ and n-type CaMnO3-δ in a direct p-n thermoelectric junction.

• Kanas, Nikola; Singh, Sathya Prakash; Rotan, Magnus; saleemi, Mohsin; Bittner, Michael; Feldhoff, Armin; Norby, Truls Eivind; Wiik, Kjell; Grande, Tor & Einarsrud, Mari-Ann (2018). Influence of processing on stability, microstructure and thermoelectric properties of Ca3Co4-xO9+δ. Journal of the European Ceramic Society.  ISSN 0955-2219.  38, s 1592- 1599 . doi: 10.1016/j.jeurceramsoc.2017.11.011 Vis sammendrag

  Due to high figure of merit, Ca3Co4-xO9+δ (CCO) has potential as p-type material for high-temperature thermoelectrics. Here, the influence of processing including solid state sintering, spark plasma sintering and post-calcination on stability, microstructure and thermoelectric properties is reported. By a new post-calcination approach, single-phase materials were obtained from precursors to final dense ceramics in one step. The highest zT of 0.11 was recorded at 800 °C for CCO with 98 and 72 % relative densities. In situ high-temperature X-ray diffraction in air and oxygen revealed a higher stability of CCO in oxygen ( ̴ 970 °C) than in air ( ̴ 930 °C), with formation of Ca3Co2O6 which also showed high stability in oxygen, even at 1125 °C. Since achievement of phase pure high density CCO by post-calcination method in air is challenging, the phase stability of CCO in oxygen is important for understanding and further improvement of the method.

• Cerretti, G; Schrade, Matthias; Song, Xin; Balke, B; Lu, H; Weidner, T; Lieberwirth, I; Panthofer, M; Norby, Truls Eivind & Tremel, Wolfgang (2017). Thermal stability and enhanced thermoelectric properties of the tetragonal tungsten bronzes Nb8-xW9+xO47 (0 < x < 5). Journal of Materials Chemistry A.  ISSN 2050-7488.  5(20), s 9768- 9774 . doi: 10.1039/c7ta01121k
• Chatzitakis, Athanasios Eleftherios; Grandcolas, Mathieu; Xu, Kaiqi; Mei, Sen; Yang, Juan; Jensen, Ingvild Julie Thue; Simon, Christian & Norby, Truls Eivind (2017). Assessing the photoelectrochemical properties of C, N, F codoped TiO2 nanotubes of different lengths. Catalysis Today.  ISSN 0920-5861.  287, s 161- 168 . doi: 10.1016/j.cattod.2016.11.040 Vis sammendrag

  The aim of this work has been the photoelectrochemical (PEC) study of nanostructured photoanodes based on TiO2. Highly ordered and well adhered TiO2 nanotubes (TNTs) of different lengths (∼2–20 μm) were prepared in a two-step process in ethylene glycol solutions containing fluorides, and detailed XPS analysis showed that they have become co-doped with C, N and F. PEC measurements revealed that increasing surface area is not followed by increase in the photoconversion efficiency, but rather that an optimal balance between electroactive surface area (ESA) and charge carrier concentration exists. TNTs of around 10 μm show the optimum incident photon-to-current efficiency (IPCE) of ∼33% and an overall photoconversion efficiency of ∼6.3% under UV illumination of 4 mW cm−2 light intensity. Finally, Mott-Schottky analysis revealed significant frequency dispersion of the estimated space charge layer capacitance, which renders the accurate estimation of the flatband position and charge carrier concentration unreliable. On the other hand, more realistic charge carrier concentrations can be obtained by normalizing the capacitance per ESA.

• Elstad, Aleksander A; Nguyen, Kevin; Sartori, Sabrina & Norby, Truls Eivind (2017). On the Conductivity of KBaPO4 and Its Decomposition in Steam and Water. Journal of the Electrochemical Society.  ISSN 0013-4651.  164(7), s F885- F888 . doi: 10.1149/2.0141709jes
• Kraia, Tzouliana; Wachowski, Sebastian Lech; Vøllestad, Einar; Strandbakke, Ragnar; Konsolakis, M.; Norby, Truls Eivind & Marnellos, G.E. (2017). Electrochemical performance of Co3O4/CeO2 electrodes in H2S/H2O atmospheres in a proton-conducting ceramic symmetrical cell with BaZr0.7Ce0.2Y0.1O3 solid electrolyte. Solid State Ionics.  ISSN 0167-2738.  306, s 31- 37 . doi: 10.1016/j.ssi.2017.04.010
• Malerød-Fjeld, Harald; Clark, Daniel Ryan; Yuste-Tirados, Irene; Zanón, Raquel; Catalán-Martinez, David; Beeaff, Dustin; Morejudo, Selene Hernandez; Vestre, Per K.; Norby, Truls Eivind; Haugsrud, Reidar; Serra, José M. & Kjølseth, Christian (2017). Thermo-electrochemical production of compressed hydrogen from methane with near-zero energy loss. Nature Energy.  ISSN 2058-7546.  2(12), s 923- 931 . doi: 10.1038/s41560-017-0029-4
• Robinson, Shay Alexander; Kjølseth, Christian & Norby, Truls Eivind (2017). Comparison of Cu and Pt point-contact electrodes on proton conducting BaZr0.7Ce0.2Y0.1O3−δ. Solid State Ionics.  ISSN 0167-2738.  306, s 38- 47 . doi: 10.1016/j.ssi.2017.02.014
• Stefan, Elena; Stange, Marit Synnøve Sæverud; Denonville, Christelle; Larring, Yngve; Hildenbrand, Nicolas; Norby, Truls Eivind & Haugsrud, Reidar (2017). Layered microstructures based on BaZr0.85Y0.15O3−δ by pulsed laser deposition for metal-supported proton ceramic electrolyser cells. Journal of Materials Science.  ISSN 0022-2461.  52(11), s 6486- 6497 . doi: 10.1007/s10853-017-0884-1
• Strandbakke, Ragnar; Vøllestad, Einar; Robinson, Shay Alexander; Fontaine, Marie-Laure & Norby, Truls Eivind (2017). Ba0.5Gd0.8La0.7Co2O6-δ infiltrated in porous BaZr0.7Ce0.2Y0.1O3 backbones as electrode material for proton ceramic electrolytes. Journal of the Electrochemical Society.  ISSN 0013-4651.  164(4), s F196- F202 . doi: 10.1149/2.0141704jes
• Stub, Sindre Østby; Vøllestad, Einar & Norby, Truls Eivind (2017). Mechanisms of Protonic Surface Transport in Porous Oxides: Example of YSZ. Journal of Physical Chemistry C.  ISSN 1932-7447.  121(23), s 12817- 12825 . doi: 10.1021/acs.jpcc.7b03005
• Vøllestad, Einar; Schrade, Matthias; Segalini, Julie; Strandbakke, Ragnar & Norby, Truls Eivind (2017). Relating defect chemistry and electronic transport in the double perovskite Ba1-xGd0.8La0.2+xCo2O6-d (BGLC). Journal of Materials Chemistry A.  ISSN 2050-7488.  5(30), s 15743- 15751 . doi: 10.1039/c7ta02659e
• Xu, Kaiqi; Chatzitakis, Athanasios Eleftherios & Norby, Truls (2017). Solid-state photoelectrochemical cell with TiO2 nanotubes for water splitting. Photochemical and Photobiological Sciences.  ISSN 1474-905X.  16(1), s 10- 16 . doi: 10.1039/c6pp00217j
• Hu, Yang; Ruud, Amund; Miikkulainen, Ville; Norby, Truls; Nilsen, Ola & Fjellvåg, Helmer (2016). Electrical characterization of amorphous LiAlO2 thin films deposited by atomic layer deposition. RSC Advances.  ISSN 2046-2069.  6(65), s 60479- 60486 . doi: 10.1039/c6ra03137d
• Kalland, Liv-Elisif Queseth; Norberg, Stefan T.; Kyrklund, Jakob; Hull, Stephen; Eriksson, Sten G.; Norby, Truls; Mohn, Chris Erik & Knee, Christopher S (2016). C-type related order in the defective fluorites La2Ce2O7 and Nd2Ce2O7 studied by neutron scattering and ab initio MD simulations. Physical Chemistry, Chemical Physics - PCCP.  ISSN 1463-9076.  18(34), s 24070- 24080 . doi: 10.1039/c6cp04708d
• Morejudo, Selene Hernandez; Zanon, R.; Escolastico, S; Yuste-Tirados, I.; Malerød-Fjeld, Harald; Vestre, P. K.; Coors, W. G.; Martinez, A.; Norby, Truls; Serra, J. M. & Kjølseth, Christian (2016). Direct conversion of methane to aromatics in a catalytic co-ionic membrane reactor. Science.  ISSN 0036-8075.  353(6299), s 563- 566 . doi: 10.1126/science.aag0274
• Polfus, Jonathan M.; Bjørheim, Tor Svendsen; Norby, Truls & Bredesen, Rune (2016). Surface defect chemistry of Y-substituted and hydrated BaZrO3 with subsurface space-charge regions. Journal of Materials Chemistry A.  ISSN 2050-7488.  4(19), s 7437- 7444 . doi: 10.1039/c6ta02067d Vis sammendrag

  First-principles calculations were utilized to elucidate the complete defect equilibria of surfaces of proton conducting BaZrO3, encompassing charged species adsorbed to the surface, defects in the surface layer as well as in the subsurface space-charge region and bulk. Defect calculations were performed for the BaZrO3 (0 0 1) surface with focus on protons, oxygen vacancies and Y-acceptor dopants as well as adsorbed hydroxide and oxide adions. Protons were found to exhibit a particularly strong tendency to segregate to the surface with a segregation energy of −1.3 eV. While the concentration of negatively charged Y-acceptors and hydroxide species on the outer surface can be quite high, they do not fully charge compensate the protons, yielding a net positive charge of the surface. The resulting surface potential can exceed 1 V, resulting in significant depletion of charge carriers in the subsurface space-charge region. Moreover, the results are discussed in relation to surface adsorption of water, and computational approaches for treating charged point defects in periodic slab cells are evaluated with respect to symmetry and charge compensation.

• Polfus, Jonathan M.; Fontaine, Marie-Laure; Thøgersen, Annett; Riktor, Marit Dalseth; Norby, Truls & Bredesen, Rune (2016). Solubility of transition metal interstitials in proton conducting BaZrO3 and similar perovskite oxides. Journal of Materials Chemistry A.  ISSN 2050-7488.  4(21), s 8105- 8112 . doi: 10.1039/c6ta02377k Vis sammendrag

  The defect chemistry of foreign transition metals in perovskite oxides was investigated by first-principles calculations with focus on Ni and Zn in Y-doped BaZrO3. Additional transition metals (Cu, Fe, Pd, Pt, and Ag) and perovskites (SrZrO3 and SrTiO3) were considered for comparison. The octahedral interstice coordinated with square-planar oxygen could accommodate smaller cations and Ni2+ was found to be the most stable, particularly in the presence of barium vacancies. Significant solubility of Ni was substantiated only for nominally A-site deficient materials under oxidizing conditions. The computational results were corroborated by experimental studies on BaZr0.85Y0.15O3−δ with 4 mol% NiO or ZnO sintering additives. While synchrotron radiation X-ray powder diffraction of the Ni containing sample showed the presence of a BaY2NiO5 secondary phase, it could not account for the nominal amount of Ni in the sample. STEM and EDS analyses of both the Zn and Ni containing samples showed that Zn accumulated in the grain boundaries while Ni was evenly distributed within the grains and grain boundaries indicating that Ni was dissolved in the BaZrO3 structure. Furthermore, metallic Ni particles appeared on the sample surface after treatment under reducing conditions in accordance with computational predictions. The influence of interstitially dissolved Ni on proton conductivity was evaluated based on trapping of protons. Barium vacancies were found to be strong proton traps, with a binding energy of −0.80 eV, while the binding energy of protons associated with adjacent Ni interstitials was reduced to −0.20 eV.

• Polfus, Jonathan M.; Norby, Truls Eivind & Bredesen, Rune (2016). Proton segregation and space-charge at the BaZrO3 (0 0 1)/MgO (0 0 1) heterointerface. Solid State Ionics.  ISSN 0167-2738.  297, s 77- 81 . doi: 10.1016/j.ssi.2016.10.010 Vis sammendrag

  Y-doped BaZrO3 (BZY) can be deposited epitaxially on MgO (0 0 1) and the considered interface serves as a model system for studying heterointerface properties of protonic conductors. In this study, the defect chemistry of the interface between ZrO2-terminated BaZrO3 (0 0 1) and MgO (0 0 1) was investigated by first-principles calculations and space-charge theory. Segregation energies from the BZY bulk to the interface ZrO2 and MgO layers were calculated for effectively charged protons, oxygen vacancies, Y-acceptors as well as cation vacancies. Protons were found to exhibit a strong tendency for segregating to the interface, particularly to an oxide ion in the MgO layer, rendering a net positive charge of the interface. According to the applied thermodynamic space-charge models, the interface potential could reach more than 1 V under the Mott-Schottky approximation, with depletion regions extending up to 2 nm into BZY. With fully equilibrated Y-segregation profiles, the interface potential was significantly diminished to about 0.2 V at 573 K and 0.025 bar H2O. While the interface was found to be close to saturated by protons under most condition, it was concluded that proton conduction along the interface could not contribute significantly to the in-plane conductivity of BZY films deposited on MgO substrate.

• Schrade, Matthias; Magraso, Anna; Galeckas, Augustinas; Finstad, Terje & Norby, Truls (2016). The Band Gap of BaPrO3 Studied by Optical and Electrical Methods. Journal of The American Ceramic Society.  ISSN 0002-7820.  99(2), s 492- 498 . doi: 10.1111/jace.13961
• Stefan, Elena & Norby, Truls (2016). Highlights from Faraday Discussion 182: Solid Oxide Electrolysis: Fuels and Feedstocks from Water and Air, York, UK, July 2015. Chemical Communications.  ISSN 1359-7345.  52(9), s 1759- 1767 . doi: 10.1039/c6cc90030e
• Strandbakke, Ragnar; Dyrlie, Oddvar; Hage, Fredrik Sydow & Norby, Truls (2016). Reaction kinetics of protons and oxide ions in LSM/lanthanum tungstate cathodes with Pt nanoparticle activation. Journal of the Electrochemical Society.  ISSN 0013-4651.  163(6), s F507- F515 . doi: 10.1149/2.0881606jes
• Ashok, Anuradha Machina; Haugsrud, Reidar; Norby, Truls & Olsen, Arne (2015). Structural study of the complex perovskite Ba4(Ba2Nb2)O11. Materials Characterization.  ISSN 1044-5803.  102, s 71- 78 . doi: 10.1016/j.matchar.2015.02.014
• Bjørheim, Tor Svendsen; Shanmugappirabu, Vijay; Haugsrud, Reidar & Norby, Truls (2015). Protons in piezoelectric langatate; La3Ga5.5Ta0.5O14. Solid State Ionics.  ISSN 0167-2738.  278(1), s 275- 280 . doi: 10.1016/j.ssi.2015.06.024

Se alle arbeider i Cristin

• Desissa, Temesgen D. & Norby, Truls Eivind (2018). Stability and properties of materials and interfaces for oxide thermoelectrics.
• Chatzitakis, Athanasios Eleftherios; Xu, Kaiqi & Norby, Truls Eivind (2017). TiO2 nanotubes as photoanode electrodes in solid-state photoelectrochemical cells.
• Chen, Min; Lozano, Helena Téllez; Druce, John; Matsumoto, Hiroshige; Sazinas, Rokas; Polfus, Jonathan M. & Norby, Truls Eivind (2017). Surface chemistry of BaZr0.9Y0.1O3-δ and its effect on the electrochemical properties of a Ni/BaZr0.9Y0.1O3-δ interface for proton ceramic electrochemical cells.
• Desissa, Temesgen D. & Norby, Truls Eivind (2017). Electrical properties and diffusion coefficient analysis of NiO:Li/ZnO:Al p-n heterojunction for oxide based thermoelectric generators.
• Fleischer, Christian; Chatzitakis, Athanasios Eleftherios; Grandcolas, Mathieu; Mei, Sen & Norby, Truls Eivind (2017). Solid-state photoelectrochemical water splitting: Application and properties of TiO2 nanotubes..
• Hancke, Ragnhild; Norby, Truls Eivind; Fontaine, Marie-Laure; Mtabazi, Sahini & Xing, Wen (2017). Self-healing ceramic membranes with increased lifetime for CO2 capture in industrial processes and power production.
• Jeu Chiem, Kevin; Prytz, Øystein & Norby, Truls Eivind (2017). Nanoscale measurements of oxidation states in the CaMnO3/LaMnO3 system using Electron Energy Loss Spectroscopy..
• Kanas, Nikola; Bittner, Michael; Singh, Sathya Prakash; Desissa, Temesgen D.; Feldhoff, Armin; Norby, Truls Eivind; Grande, Tor; Wiik, Kjell & Einarsrud, Mari-Ann (2017). Development of all-oxide thermoelectric device.
• Løken, Andreas; Haugsrud, Reidar; Norby, Truls Eivind & Bjørheim, Tor Svendsen (2017). Hydration thermodynamics of oxides.
• Norby, Truls Eivind (2017). Advances in Proton Ceramic Fuel Cells, Steam Electrolyzers, and Dehydrogenation Reactors Based on Materials and Process Optimizations.
• Norby, Truls Eivind (2017). Grønn Gjødselproduksjon i 2050. Noe nytt under solen?.
• Norby, Truls Eivind (2017). High temperature electrolysis using proton conducting ceramic electrolytes.
• Norby, Truls Eivind (2017). Hydrogen.
• Norby, Truls Eivind (2017). Novel approaches for conversion of H2O, CO2, and N2 with renewables.
• Norby, Truls Eivind (2017). Principles and applications of coexistent p-n junctions.
• Norby, Truls Eivind (2017). Teknologi kan redusere klimagassutslipp i landbruket.
• Norby, Truls Eivind; Hancke, Ragnhild; Fontaine, Marie-Laure & Grande, Tor (2017). Self-Healing and Self-Assembling Ceramic Electrolytes and Membranes.
• Robinson, Shay Alexander; Norby, Truls Eivind; Kjølseth, Christian & Coors, W. Grover (2017). Development of Cu-Based Electrodes for Proton-Conducting Membrane Reactors. Series of dissertations submitted to the Faculty of Mathematics and Natural Sciences, University of Oslo.. 1906.
• Singh, Sathya Prakash; Kanas, Nikola; Norby, Truls Eivind; Johnsson, Mats; Einarsrud, Mari-Ann & Wiik, Kjell (2017). Thermoelectric properties of (La0.12Sr0.88)0.95TiO3 between 100 and 900 oC at reducing conditions.
• Strandbakke, Ragnar; Vøllestad, Einar & Norby, Truls Eivind (2017). Development of oxygen-side electrodes for proton conducting fuel cells and electrolysers.
• 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).
• 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).
• Stub, Sindre Østby; Haugsrud, Reidar & Norby, Truls Eivind (2017). Protonic Conduction in Porous Oxides.
• Stub, Sindre Østby; Vøllestad, Einar; Rørvik, Per Martin & Norby, Truls Eivind (2017). On the role of grain boundaries in surface protonics.
• Stub, Sindre Østby; Vøllestad, Einar; Rørvik, Per Martin & Norby, Truls Eivind (2017). Protonic conduction in porous oxides.
• Xu, Kaiqi; Chatzitakis, Athanasios Eleftherios; Bjørheim, Tor Svendsen & Norby, Truls Eivind (2017). Fuels from the sun, sea and air-by solid-state photoelectrochemical cell.
• Xu, Kaiqi; Chatzitakis, Athanasios Eleftherios; Bjørheim, Tor Svendsen & Norby, Truls Eivind (2017). Tantalum oxynitride for photoelectrochemical water splitting.
• Xu, Kaiqi; Chatzitakis, Athanasios Eleftherios; Norby, Truls Eivind; Mei, Sen; Juan, Yang; Grandcolas, Mathieu & Simen, Christian (2017). Solid-state photoelectrochemical Cell with Tantalum Nitride Nanotubes as Photoanode.
• Yang, Juan; Mei, Sen; Grandcolas, Mathieu; Simon, Christian; Xu, Kaiqi; Chatzitakis, Athanasios Eleftherios; Norby, Truls Eivind; Yang, Mingyi; Backe, Paul Hoff & Bjørås, Magnar (2017). Synthesis of Nanosized Cobalt Oxides and Application in a Bio-hybrid Photoelectrochemical Cell for CO2 Utilization. Vis sammendrag

  CO2 capture and utilization (CCU) can alleviate the disastrous effects of greenhouse gas (GHG) emissions form the use of fossil fuels. The use of CO2 emission as feedstock for direct conversion into valuable chemicals has attracted increasing research interest worldwide. A number of approaches, such as chemical, electrochemical, photochemical and biological routes have used CO2 as a sustainable carbon resource for the production of chemicals. In the present CO2BioPEC project, a novel hybrid photoelectrochemical concept, based on solar energy and formate dehydrogenase biocatalyst is applied, as illustrated in Figure 1 (left). This multidisciplinary project aims at demonstrating a bio-hybrid photoelectrochemical cell, in which solar energy is efficiently captured and utilized to convert CO2 into energy-rich compounds, using formate dehydrogenase enzymes as biocatalysts. Cobalt oxide is a low-cost material with a band gap that can absorb visible light. It is also a promising co-catalyst that has been widely used for oxygen evolution route. In the present work, nanosized cobalt oxide was synthesized and used as a co-catalyst on the photoanode. The results showed that the formation of cobalt oxides (Co3O4, CoOOH and Co(OH)2) is strongly dependent on the temperature and reaction time. The photochemical efficiency will be further investigated by impregnating nanosized cobalt oxides onto Ta3N4 /TaON nanotubes.

• Chatzitakis, Athanasios Eleftherios; Grandcolas, Mathieu; Xu, Kaiqi; Mei, Sen; Yang, Juan; Simon, Christian & Norby, Truls (2016). Assessing the photoelectrocatalytic activity of C, N, F codoped TiO2 nanotubes of different lengths for oxygen evolution.
• Chen, Min & Norby, Truls (2016). Space Charge Layer Effect at the Ni/BaZr0.9Y0.1O3-δ Electrode Interface in Proton Ceramic electrochemical Cells.
• Chen, Min & Norby, Truls (2016). Surface chemistry of BaZr0.9Y0.1O3-δ and its effect on the electrochemical properties of a Ni/BaZr0.9Y0.1O3-δ interface.
• Desissa, Temesgen D. & Norby, Truls (2016). A p-Ni1-xLixO and n-Zn1-xAlxO p-n junctions for oxide-based thermoelectric modules. Vis sammendrag

  A p-type Ni0.98Li0.02O and n-type Zn0.98Al0.02O thermoelectric materials have been synthesized from their respective powder precursors via solid state synthesis technique from which a pellets were obtained by uniaxial pressing. The pellets were sintered at a sintering temperature of 1523 K and 1623 K for Ni0.98Li0.02O and Zn0.98Al0.02O, respectively. The sintered samples were carefully polished to a surface finish of ¼ μm by using a diamond abrasive before establishing a p-n junction. After a p-n junction is formed, an I-V and C-V measurement has been performed. The p-n junction is rectifying in the lower temperature region and became ohmic in the highest temperature. A p-n junction resistivity was delineated from the overall resistivity and it constituted the main part of the overall resistivity. A built-in voltage of 0.875± 0.039 V was obtained from a C-V measurement at a frequency of 1 MHz at a temperature of 1173 K. Additionally, the p-n junction was annealed in ambient air at 1173 K for 160 hours to determine inter-diffusion coefficient using an electron probe micro analyzer (EPMA). The bulk diffusion coefficient of Ni2+ and Zn2+ was about 4.08*10-15 cm2/s and 4.51 * 10-15 cm2/s, respectively, after fitting to the solution of Fick’s second law of diffusion equation with a semi-infinite source type.

• Fleischer, Christian; Xu, Kaiqi; Chatzitakis, Athanasios Eleftherios & Norby, Truls Eivind (2016). Development of high surface area TiO2 photo-electrodes and the significance of solid-state proton conductor in water splitting photoelectrochemical cell..
• Fontaine, Marie-Laure; Denonville, Christelle; Strandbakke, Ragnar; Serra, José Manuel; Beeaff, Dustin R.; Vigen, Camilla Kaori; Vøllestad, Einar & Norby, Truls (2016). Development of Tubular Proton Ceramic Electrolysers (PCEs).
• Fontaine, Marie-Laure; Denonville, Christelle; Strandbakke, Ragnar; Vøllestad, Einar; Norby, Truls; Bredesen, Rune; Vigen, Camilla Kaori & Beeaff, Dustin R. (2016). Proton conducting electrolytes integrated in tubular segmented-in-series cells for pressurized hydrogen production.
• Fontaine, Marie-Laure; Vøllestad, Einar; Polfus, Jonathan M.; Denonville, Christelle; Xing, Wen; Li, Zuoan; Norby, Truls & Bredesen, Rune (2016). Proton Conducting Electrolysers with Tubular Segmented-in-series Cells for Hydrogen Production.
• Fontaine, Marie-Laure; Xing, Wen; Bredesen, Rune; Denonville, Christelle; Polfus, Jonathan M.; Strandbakke, Ragnar; Vøllestad, Einar; Norby, Truls; Beeaff, Dustin R. & Vigen, Camilla Kaori (2016). Proton conducting electrolysers with tubular segmented-in-series cells for hydrogen production.
• Fontaine, Marie-Laure; Xing, Wen; Li, Zuoan; Denonville, Christelle; Norby, Truls & Bredesen, Rune (2016). Segmented-in-series proton conducting tubular electrolysers.
• Foss, Carl Erik Lie; Sunde, Svein; Norby, Truls; Sahoo, Prangya Parimita; Grandcolas, Mathieu; Polfus, Jonathan M. & Xing, Wen (2016). Photofixation of N2 to NH3/NOx.
• Grandcolas, Mathieu; Sahoo, Prangya Parimita; Foss, Carl Erik Lie; Xing, Wen; Polfus, Jonathan M.; Sunde, Svein; Chatzitakis, Athanasios Eleftherios & Norby, Truls (2016). Novel photoelectrocatalytic concepts for conversion of nitrogen to fuels and chemicals.
• Norby, Truls (2016). Defect chemistry of ionic oxides.
• Norby, Truls (2016). Energy Materials for Hydrogen and Chemicals in the Future.
• Norby, Truls (2016). Hydrogen - helt sikkert!.
• Norby, Truls (2016). Hydrogensamfunnet. Løsningen - eller hvert fall en del av den..
• Norby, Truls (2016). Inorganic protonic conductors.
• Norby, Truls (2016). Proton ceramics for hydrogen technologies.
• Norby, Truls (2016). Proton conducting materials from ambient to high temperatures.
• Norby, Truls (2016). Protonics og termoelektrisitet.
• Norby, Truls; Fontaine, Marie-Laure; Strandbakke, Ragnar; Denonville, Christelle; Vøllestad, Einar; Vigen, Camilla Kaori; Beeaff, Dustin R. & Bredesen, Rune (2016). Development of tubular proton conducting electrolysers.
• Norby, Truls & Løken, Andreas (2016). Proton defect interactions in oxides.
• Norby, Truls; Strandbakke, Ragnar; Chen, Min; Robinson, Shay Alexander & Kjølseth, Christian (2016). Fundamentals of electrodes for ceramic proton conducting electrolytes.
• Norby, Truls; Strandbakke, Ragnar; Vøllestad, Einar; Chen, Min; Robinson, Shay Alexander & Kjølseth, Christian (2016). Proton ceramic electrodics.
• Norby, Truls; Tyagi, Sarika; Sigurbjörnsson, Omar & Vøllestad, Einar (2016). Steam electrolysis using proton ceramic cells and modules - Design and performance modelling.
• Polfus, Jonathan M.; Norby, Truls & Bredesen, Rune (2016). Proton Conduction Across Interfaces in Y-doped BaZrO3 Investigated by First-Principles Calculations.
• Robinson, Shay Alexander; Norby, Truls & Kjølseth, Christian (2016). Comparison of Cu and Pt Point-Contact Electrodes on a BZCY72 Electrolyte.
• Rørvik, Per Martin; Arstad, Bjørnar; Jørgensen, Sissel; Stub, Sindre Østby; Norby, Truls & Hansen, Eddy Walther (2016). 1H-NMR and Resistance Study of Surface-Adsorbed Water in Porous YSZ.
• Saeed, Sarmad Waheed; Bjørheim, Tor Svendsen & Norby, Truls (2016). Defect Chemistry of BaZrO3 at High Oxygen Partial Pressures.
• Saeed, Sarmad Waheed; Bjørheim, Tor Svendsen & Norby, Truls (2016). Defect chemistry of BaZrO3/SrTiO3 nanostructures from first principles.
• Stefan, Elena; Stange, Marit Synnøve Sæverud; Denonville, Christelle; Larring, Yngve; Norby, Truls & Haugsrud, Reidar (2016). Fabrication of Multi-layered Microstructures based on BaZr0.85Y0.15O3-δ for Metal Supported Proton Ceramic Electrolyzer Cells by Pulsed Laser Deposition.
• Strandbakke, Ragnar; Vøllestad, Einar; Prato, Rafael Alberto; Wragg, David & Norby, Truls (2016). Structural and electrochemical properties of hydrated mixed conductor Ba1-xGd0.8La0.2+xCo2O6-d.
• Strandbakke, Ragnar; Vøllestad, Einar; Prato, Rafael Alberto; Wragg, David; Sartori, Sabrina & Norby, Truls (2016). Structural and electrochemical properties of hydrated mixed conductor Ba1-xGd0.8La0.2+xCo2O6-d.
• Stub, Sindre Østby; Vøllestad, Einar; Rørvik, Per Martin & Norby, Truls (2016). On the interaction of grain boundaries and protonic surface transport in porous oxides.
• Tyagi, Sarika & Norby, Truls (2016). Economic viability of high temperature electrolysis integration with renewable sources for a power to gas solution.
• Vøllestad, Einar; Fontaine, Marie-Laure; Denonville, Christelle; Strandbakke, Ragnar; Norby, Truls; Vigen, Camilla Kaori & Beeaff, Dustin R. (2016). Development of tubular proton conducting electrolysers.
• Vøllestad, Einar; Strandbakke, Ragnar; Beaff, Dustin & Norby, Truls (2016). Proton Ceramic Steam Electrolysers.
• Vøllestad, Einar; Strandbakke, Ragnar; Beeaff, Dustin & Norby, Truls (2016). Proton Ceramic Steam Electrolysers.
• Vøllestad, Einar; Strandbakke, Ragnar & Norby, Truls (2016). Tailoring the properties of BGLC double perovskites.
• Xu, Kaiqi; Chatzitakis, Athanasios Eleftherios & Norby, Truls (2016). An All-Solid-State Photoelectrochemical Cell for Water Splitting.
• Xu, Kaiqi & Norby, Truls Eivind (2016). All-Solid-State Photoelectrochemical Water Splitting for Hydrogen Generation. Vis sammendrag

  The combination of solar energy and water splitting hydrogen production results in a feasible, prospective energy conversion and storage process—photoelectrochemical (PEC) water splitting. In this work, an all-solid-state PEC cell has been fabricated and its performance with different photoanodes has been studied. An attempt to move one step further to fabricate an even more compact solid-state PEC cell using a proton-electron mixed conducting membrane has also been carried out later. In the photoanodes preparation stage, titania with different morphologies, e.g., drop-cast P25 titania nanoparticles, thermally treated Ti foil and highly organized titania nanotubes (TNT), are prepared and tested for their intrinsic properties, such as the donor density, flatband potential, etc. In particular, TNTs are synthesized by a 2-step anodization method, with immersing pretreatment, long and stable TNTs can be grown on a thin Ti substrate. Three TNT samples synthesized for 5, 20 and 30 min in the 2nd anodization step have been studied, and later applied in the PEC cell. The Type 1 solid-state PEC cell is fabricated by simply attaching the photoanode and the cathode onto the two sides of a Nafion proton conducting membrane. In this way, water oxidation reaction and proton reduction reaction will take place in each side of the membrane, hence gases are separated as soon as they are generated. The cathode consists of the carbon paper as the substrate, and the platinum coated carbon nanoparticles (Pt-C) as the electrocatalyst, which is connected with the photoanode through an external circuit. Regarding the photo-to-current performance, PEC cells employed with TNT as their photoanodes perform better than the ones with other photoanodes. Furthermore, the ionic conductivity around the TNT photoanodes has a significant impact on the overall cell performance. With deionized water as the liquid environment, the cell employed with the TNT 5 min photoanode gives the highest efficiency, while replacing the deionized water with a 0.5 M sodium sulphate solution makes the cell with the TNT 30 min sample perform the best. The hydrogen production of the Type 1 solid-state PEC cell was confirmed by GC measurements. When it comes to the Type 2 cell, the external circuit was removed, and the Nafion membrane was integrated with the carbon paper to form a protonelectron mixed conducting membrane (MCM). Electrons and protons generated by the photoanode during the oxidation half reaction were expected to transport through the integrated membrane simultaneously. The electrocatalyst—Pt-C was deposited directly on one side of the MCM, so that proton and hydrogen can easily recombine into hydrogen molecules that side. The concept of producing hydrogen by this type of cell was confirmed by the detection of a hydrogen peak from GC measurements, in which a basic solution was introduced to the photoanode in order to enlarge the chemical potential difference between the two sides of the MCM. However, involving alkalies leads to the carbon corrosion, which results in the formation of carbonate ions. Consequently, a relatively large methane production was observed, since the reaction from carbonate ions to methane is energetically more favorable than hydrogen production. In conclusion, a compact, robust, solid-state PEC cell for water splitting hydrogen generation can be built through a simple process, and a novel nanostructure modification of titania as the photoanode can enhance the overall cell performance. Protons and electrons generated during the water oxidation can pass through a proton-electron MCM simultaneously, and get recombined into hydrogen where the electrocatalyst is present, which results in a more compact solid-state PEC cell.

• Chatzitakis, Athanasios Eleftherios & Norby, Truls (2015). Solar hydrogen production.
• Chatzitakis, Athanasios Eleftherios & Norby, Truls (2015). Solid electrolytes for photoelectrochemical cells.
• Chatzitakis, Athanasios Eleftherios; Xu, Kaiqi; Boye, Ole; Backe, Paul Hoff; Bjorås, Magnar; Dalhus, Bjørn; Grandcolas, Mathieu; Mei, Sen; Simon, Christian; Tilset, Bente Gilbu; Yang, Juan; Yang, Mingyi & Norby, Truls (2015). Solar based H2 generation in a novel photoelectrochemical-enzymatic hybrid cell.
• Chen, Min & Norby, Truls (2015). Min Chen and Truls Norby, SPACE CHARGE LAYER EFFECT AT NICKEL/BaZr0.9Y0.1O3-δ INTERFACES IN PROTONIC CERAMIC FUEL CELLS (first generation model).
• Chen, Min & Norby, Truls (2015). SPACE CHARGE LAYER EFFECT AT NICKEL/BaZr0.9Y0.1O3-δ INTERFACES IN PROTONIC CERAMIC FUEL CELLS (second generation model).

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