Truls Norby

• Gunnæs, Anette Eleonora; Tofan, Raluca; Berland, Kristian; Gorantla, Sandeep Madhukar; Storaas, Thomas Aarflot; Desissa, Temesgen Debelo; Schrade, Matthias; Persson, Clas; Einarsrud, Mari-Ann; Wiik, Kjell; Norby, Truls Eivind & Kanas, Nikola (2020). Chemical stability of Ca3Co4−xO9+δ/CaMnO3−δ p–n junction for oxide-based thermoelectric generators. RSC Advances.  ISSN 2046-2069.  10(9), s 5026- 5031 . doi: 10.1039/c9ra07159h Show summary

  An all-oxide thermoelectric generator for high-temperature operation depends on a low electrical resistance of the direct p–n junction. Ca3Co4−xO9+δ and CaMnO3−δ exhibit p-type and n-type electronic conductivity, respectively, and the interface between these compounds is the material system investigated here. The effect of heat treatment (at 900 °C for 10 h in air) on the phase and element distribution within this p–n junction was characterized using advanced transmission electron microscopy combined with X-ray diffraction. The heat treatment resulted in counter diffusion of Ca, Mn and Co cations across the junction, and subsequent formation of a Ca3Co1+yMn1−yO6 interlayer, in addition to precipitation of Co-oxide, and accompanying diffusion and redistribution of Ca across the junction. The Co/Mn ratio in Ca3Co1+yMn1−yO6 varies and is close to 1 (y = 0) at the Ca3Co1+yMn1−yO6–CaMnO3−δ boundary. The existence of a wide homogeneity range of 0 ≤ y ≤ 1 for Ca3Co1+yMn1−yO6 is corroborated with density functional theory (DFT) calculations showing a small negative mixing energy in the whole range.

• Barakzehi, Marjan; Montazer, Majid; Sharif, Farhad; Norby, Truls Eivind & Chatzitakis, Athanasios Eleftherios (2020). MOF-modified polyester fabric coated with reduced graphene oxide/polypyrrole as electrode for flexible supercapacitors. Electrochimica Acta.  ISSN 0013-4686.  336, s 135743 . doi: 10.1016/j.electacta.2020.135743
• Bondevik, Tarjei; Polfus, Jonathan Marc & Norby, Truls Eivind (2020). Disagreements between space charge models and grain boundary impedance data in yttrium-substituted barium zirconate. Solid State Ionics.  ISSN 0167-2738.  353 . doi: 10.1016/j.ssi.2020.115369
• Getz, Marit Norderhaug; Chatzitakis, Athanasios Eleftherios; Liu, Xin; Almeida Carvalho, Patricia; Bjørheim, Tor Svendsen & Norby, Truls Eivind (2020). Voids in walls of mesoporous TiO2 anatase nanotubes by controlled formation and annihilation of protonated titanium vacancies. Materials Chemistry and Physics.  ISSN 0254-0584.  239, s 121953 . doi: https://doi.org/10.1016/j.matchemphys.2019.121953 Show summary

  Amorphous TiO2 nanotubes (TNTs) grown anodically on Ti metal in aqueous electrolytes show a crystallization behaviour strongly dependent on the atmosphere used during annealing at high temperature. In wet oxidizing conditions, the amorphous TNTs walls transform into relatively large and well crystallized anatase-like domains permeated by prismatic voids. On the other hand, crystallization of the amorphous nanotubes under dry reducing conditions induces nanocrystalline aggregates that do not show prismatic voids and exhibit different electronic properties. Supported by density functional theory calculations, it is argued that the formation or absence of voids can be understood in terms of formation and condensation of protonated titanium vacancies. Tunable morphology through defect chemical engineering as such, enables TNTs with increased surface area and catalytic activity, which find potential application in supercapacitors, sensors, photocatalysis, photoelectrochemistry, and dye-sensitized solar cells.

• Husai, Yudai; Murakami, Kota; Kamite, Yukiko; Ma, Quanbao; Vøllestad, Einar; Manabe, Ryo; Matsuda, Takumi; Ogo, Shuhei; Norby, Truls Eivind & Sekine, Yasushi (2020). First observation of surface protonics on SrZrO3 perovskite under a H2 atmosphere. Chemical Communications.  ISSN 1359-7345. . doi: 10.1039/C9CC08757E
• Xu, Kaiqi; Chatzitakis, Athanasios Eleftherios; Risbakk, Sanne; Yang, Mingyi; Backe, Paul Hoff; Grandcolas, Mathieu; Bjørås, Magnar & Norby, Truls Eivind (2020). High performance and toxicity assessment of Ta3N5 nanotubes for photoelectrochemical water splitting. Catalysis Today.  ISSN 0920-5861. . doi: 10.1016/j.cattod.2019.12.031 Full text in Research Archive. Show summary

  In this work, Co-based cocatalysts are electrodeposited on mesoporous Ta3N5 nanotubes. The electrodeposition time is varied and the optimized photoelectrode reaches a photocurrent density of 6.3 mA/cm2 at 1.23 V vs. SHE, under simulated solar illumination of 1 Sun, in 1 M NaOH. The best performing electrode, apart from the high photocurrent density, shows improved stability under intense photoelectrochemical water splitting conditions. The dual function of the cocatalyst to improve not only the photoelectrochemical performance, but also the stability, is highlighted. Moreover, we adopted a simple protocol to assess the toxicity of Co and Ta contained nanostructured materials (representing used photoelectrodes) employing the human cell line HeLa S3 as target cells.

• Singh, Sathya Prakash; Kanas, Nikola; Desissa, Temesgen Debelo; Einarsrud, Mari-Ann; Norby, Truls Eivind & Wiik, Kjell (2019). Thermoelectric properties of non-stoichiometric CaMnO3-d composites formed by redox-activated exsolution.. Journal of the European Ceramic Society.  ISSN 0955-2219.  40(4), s 1344- 1351 . doi: 10.1016/j.jeurceramsoc.2019.11.027 Full text in Research Archive.
• Singh, Sathya Prakash; Kanas, Nikola; Desissa, Temesgen Debelo; Johnsson, Mats; Einarsrud, Mari-Ann; Norby, Truls Eivind & Wiik, Kjell (2019). Thermoelectric properties of A-site deficient La-doped SrTiO3 at 100–900 °C under reducing conditions. Journal of the European Ceramic Society.  ISSN 0955-2219.  40(2), s 401- 407 . doi: 10.1016/j.jeurceramsoc.2019.09.024 Full text in Research Archive.
• Barakezehi, Marjan; Montazer, Majid; Sharif, Farhad; Norby, Truls Eivind & Chatzitakis, Athanasios Eleftherios (2019). A textile-based wearable supercapacitor using reduced graphene oxide/polypyrrole composite. Electrochimica Acta.  ISSN 0013-4686.  305, s 187- 196 . doi: 10.1016/j.electacta.2019.03.058
• Bondevik, Tarjei; Ness, Heine Håland; Bazioti, Kalliopi; Norby, Truls Eivind; Løvvik, Ole Martin; Koch, Christoph T. & Prytz, Øystein (2019). Investigation of the electrostatic potential of a grain boundary in Y-substituted BaZrO3 using inline electron holography. Physical Chemistry, Chemical Physics - PCCP.  ISSN 1463-9076.  21(32), s 17662- 17672 . doi: 10.1039/c9cp02676b Full text in Research Archive. Show summary

  We apply inline electron holography to investigate the electrostatic potential across an individual BaZr0.9Y0.1O3 grain boundary. With holography, we measure a grain boundary potential of −1.3 V. Electron energy loss spectroscopy analyses indicate that barium vacancies at the grain boundary are the main contributors to the potential well in this sample. Furthermore, geometric phase analysis and density functional theory calculations suggest that reduced atomic density at the grain boundary also contributes to the experimentally measured potential well.

• Grandcolas, Mathieu; Wabende, Brian; Yang, Juan; Mei, Sen; Xu, Kaiqi; Norby, Truls Eivind & Chatzitakis, Athanasios Eleftherios (2019). Preparation of TiO2 rutile nanorods decorated with cobalt oxide nanoparticles for solar photoelectrochemical activity. Materials letters (General ed.).  ISSN 0167-577X.  247, s 1- 3 . doi: 10.1016/j.matlet.2019.03.087 Show summary

  The present paper investigates the preparation of titanium dioxide (TiO2) nanorods decorated with cobalt oxide (Co3O4) nanoparticles and its application as solar photoelectrocatalyst. TiO2 rutile nanorods have been prepared on conductive glass via a hydrothermal reaction in acidic media, shaped as squared rods with an average length of 1.7 µm and thicknesses between 50 and 120 nm. Co3O4 nanoparticles with an average diameter of 30 nm were synthesized using a simple precipitation method. Spin coating the nanoparticles on the TiO2 nanorods shows enhanced photocurrents under simulated solar light up to 1.3 mA/cm2 at 1.6 V vs. SHE.

• Han, Feng; Zhou, Xingping; Dayaghi, Amir Masoud; Norby, Truls Eivind; Stange, Marit Synnøve Sæverud; Sata, Noriko & Costa, Remi (2019). Development of Metal Supported Cells Using BaZrO3-Based Proton Conducting Ceramics. ECS Transactions.  ISSN 1938-5862.  91(1), s 1035- 1045 . doi: 10.1149/09101.1035ecst
• Kanas, Nikola; Singh, Sathya Prakash; Rotan, Magnus; Desissa, Temesgen Debelo; Grande, Tor; Wiik, Kjell; Norby, Truls Eivind & Einarsrud, Mari-Ann (2019). Thermoelectric Properties of Ca3Co2−xMnxO6 (x = 0.05, 0.2, 0.5, 0.75, and 1). Materials.  ISSN 1996-1944.  12(3) . doi: 10.3390/ma12030497 Full text in Research Archive. Show summary

  High-temperature instability of the Ca3Co4−yO9+δ and CaMnO3−δ direct p-n junction causing the formation of Ca3Co2−xMnxO6 has motivated the investigation of the thermoelectric performance of this intermediate phase. Here, the thermoelectric properties comprising Seebeck coefficient, electrical conductivity, and thermal conductivity of Ca3Co2−xMnxO6 with x = 0.05, 0.2, 0.5, 0.75, and 1 are reported. Powders of the materials were synthesized by the solid-state method, followed by conventional sintering. The material Ca3CoMnO6 (x = 1) demonstrated a large positive Seebeck coefficient of 668 μV/K at 900 °C, but very low electrical conductivity. Materials with compositions with x < 1 had lower Seebeck coefficients and higher electrical conductivity, consistent with small polaron hopping with an activation energy for mobility of 44 ± 6 kJ/mol and where both the concentration and mobility of hole charge carriers were proportional to 1−x. The conductivity reached about 11 S·cm−1 at 900 °C for x = 0.05. The material Ca3Co1.8Mn0.2O6 (x = 0.2) yielded a maximum zT of 0.021 at 900 °C. While this value in itself is not high, the thermodynamic stability and self-assembly of Ca3Co2−xMnxO6 layers between Ca3Co4−yO9+δ and CaMnO3−δ open for new geometries and designs of oxide-based thermoelectric generators.

• Liu, Xin; Almeida Carvalho, Patricia; Getz, Marit Norderhaug; Norby, Truls Eivind & Chatzitakis, Athanasios Eleftherios (2019). Black Anatase TiO2 Nanotubes with Tunable Orientation for High Performance Supercapacitors. Journal of Physical Chemistry C.  ISSN 1932-7447.  126(36), s 21391- 21940 . doi: 10.1021/acs.jpcc.9b05070 Show summary

  Black TiO2 is a versatile material that finds many applications in the field of photocatalysis but also in energy storage devices, such as supercapacitors. In this work, a new method is developed for the synthesis of black TiO2 in the form of nanotubes. Amorphous TiO2 nanotubes (TNTs) are annealed and reduced in the presence of CaH2, and by a simple manipulation, we are able to obtain control over the preferred crystal orientation. The reduced TNTs show high power and energy densities, as well as unprecedented stability under intensive charge/discharge cycling. The oriented reduced TNTs show metallic-like behavior with improved conductivity when compared to the polycrystalline analogue. This work contributes to the development of highly robust and efficient oxides for electrode material in supercapacitors.

• Liu, Xin; Bjørheim, Tor Svendsen; Vines, Lasse; Fjellvåg, Øystein; Granerød, Cecilie Skjold; Prytz, Øystein; Yamamoto, Takafumi; Kageyama, Hiroshi; Norby, Truls Eivind & Haugsrud, Reidar (2019). Highly Correlated Hydride Ion Tracer Diffusion in SrTiO3–xHx Oxyhydrides. Journal of the American Chemical Society.  ISSN 0002-7863.  141(11), s 4653- 4659 . doi: 10.1021/jacs.8b12985 Full text in Research Archive.
• Morland, Bjørn Helge; Norby, Truls Eivind; Tjelta, Morten & Svenningsen, Gaute (2019). Effect of SO2, O2, NO2, and H2O Concentrations on Chemical Reactions and Corrosion of Carbon Steel in Dense Phase CO2. Corrosion.  ISSN 0010-9312.  75(11), s 1327- 1338 . doi: 10.5006/3111 Full text in Research Archive.
• Morland, Bjørn Helge; Tjelta, Morten; Norby, Truls Eivind & Svenningsen, Gaute (2019). Acid reactions in hub systems consisting of separate non-reactive CO2 transport lines. International Journal of Greenhouse Gas Control.  ISSN 1750-5836.  87, s 246- 255 . doi: 10.1016/j.ijggc.2019.05.017 Full text in Research Archive.
• Norby, Truls Eivind; Jensen, Emil Høj & Sartori, Sabrina (2019). Deep decarbonization efforts in Norway for energy sustainability. MRS Energy & Sustainability.  ISSN 2329-2229.  6 . doi: 10.1557/mre.2019.12
• Saeed, Sarmad Waheed; Norby, Truls Eivind & Bjørheim, Tor Svendsen (2019). Charge-Carrier Enrichment at BaZrO3/SrTiO3 Interfaces. Journal of Physical Chemistry C.  ISSN 1932-7447.  123(34), s 20808- 20816 . doi: 10.1021/acs.jpcc.9b06296
• Sazinas, Rokas; Sunding, Martin Fleissner; Thøgersen, Annett; Sakaguchi, Isao; Norby, Truls Eivind; Grande, Tor & Polfus, Jonathan M. (2019). Surface reactivity and cation non-stoichiometry in BaZr1-xYxO3-δ (x=0-0.2) exposed to CO2 at elevated temperature. Journal of Materials Chemistry A.  ISSN 2050-7488.  7(8), s 3848- 3856 . doi: 10.1039/c8ta11021b Full text in Research Archive.
• Stange, Marit Synnøve Sæverud; Dayaghi, Amir Masoud; Denonville, Christelle; Larring, Yngve; Rørvik, Per Martin; Haugsrud, Reidar & Norby, Truls Eivind (2019). Fabrication of metal-supported proton-conducting electrolysers with thin film Sr- And Ce-doped BZY electrolyte. ECS Transactions.  ISSN 1938-5862.  91(1), s 941- 949 . doi: 10.1149/09101.0941ecst Show summary

  n this work, we present fabrication and initial testing of metal-supported proton ceramic electrolyser (MS-PCEC) single cells with a thin electrolyte. Plansee ITM porous metal is used as metal support. Spray-coating is used to deposit a conducting layer of La1-xSrxTi1-yNiyO3-δ (LSTN) which is used for low temperature (600-800 °C) deposition of a gas-tight, thin-film layer (~2 μm) of electrolyte by pulsed laser deposition (PLD). Post-annealing of the electrolyte is evaluated to improve its performance. In order to have a smaller thermal expansion coefficient (TEC) mismatch towards LSTN (~10-11 × 10-6 K-1), we developed a new Sr- and Ce-doped proton-conducting electrolyte, yielding a larger TEC (~10-11 × 10-6 K-1) compared to BZY (~8 × 10-6 K-1). The cell with Pt as air electrode shows acceptable open circuit voltage and low overpotentials at 600 °C, demonstrating the potential of developing the first working MS-PCEC.

• Sun, Xinwei; Simonsen, Stian Christopher; Norby, Truls Eivind & Chatzitakis, Athanasios Eleftherios (2019). Composite Membranes for High Temperature PEM Fuel Cells and Electrolysers: A Critical Review. Membranes.  ISSN 2077-0375.  9(7) . doi: 10.3390/membranes9070083
• Vøllestad, Einar; Strandbakke, Ragnar; Tarach, Mateusz; Catalán-Martinez, David; Fontaine, Marie-Laure; Beeaff, Dustin; Clark, Daniel Ryan; Serra, José M. & Norby, Truls Eivind (2019). Mixed proton and electron conducting double perovskite anodes for stable and efficient tubular proton ceramic electrolysers. Nature Materials.  ISSN 1476-1122.  18(7), s 752- 759 . doi: 10.1038/s41563-019-0388-2 Show summary

  Hydrogen production from water electrolysis is a key enabling energy storage technology for the large-scale deployment of intermittent renewable energy sources. Proton ceramic electrolysers (PCEs) can produce dry pressurized hydrogen directly from steam, avoiding major parts of cost-driving downstream separation and compression. However, the development of PCEs has suffered from limited electrical efficiency due to electronic leakage and poor electrode kinetics. Here, we present the first fully operational BaZrO3-based tubular PCE, with 10 cm2 active area and a hydrogen production rate above 15 Nml min−1. The novel steam anode Ba1−xGd0.8La0.2+xCo2O6−δ exhibits mixed p-type electronic and protonic conduction and low activation energy for water splitting, enabling total polarization resistances below 1 Ω cm2 at 600 °C and Faradaic efficiencies close to 100% at high steam pressures. These tubular PCEs are mechanically robust, tolerate high pressures, allow improved process integration and offer scale-up modularity.

• Xing, Wen; Li, Zuoan; Peters, Thijs; Fontaine, Marie-Laure; McCann, Michael; Evans, Anna; Norby, Truls Eivind & Bredesen, Rune (2019). Improved CO2 flux by dissolution of oxide ions into the molten carbonate phase of dual-phase CO2 separation membranes. Separation and Purification Technology.  ISSN 1383-5866.  212, s 723- 727 . doi: 10.1016/j.seppur.2018.11.090 Full text in Research Archive.
• Xu, Kaiqi; Chatzitakis, Athanasios Eleftherios; Jensen, Ingvild Julie Thue; Grandcolas, Mathieu & Norby, Truls Eivind (2019). Ta3N5/Co(OH)x composites as photocatalysts for photoelectrochemical water splitting. Photochemical and Photobiological Sciences.  ISSN 1474-905X.  18(4), s 837- 844 . doi: 10.1039/c8pp00312b
• Xu, Kaiqi; Chatzitakis, Athanasios Eleftherios; Vøllestad, Einar; Ruan, Qiushi; Tang, Junwang & Norby, Truls Eivind (2019). Hydrogen from wet air and sunlight in a tandem photoelectrochemical cell. International journal of hydrogen energy.  ISSN 0360-3199.  44(2), s 587- 593 . doi: 10.1016/j.ijhydene.2018.11.030 Full text in Research Archive.
• Kanas, Nikola; Bittner, Michael; Desissa, Temesgen Debelo; Singh, Sathya Prakash; Norby, Truls Eivind; Feldhoff, Armin; Grande, Tor; Wiik, Kjell & Einarsrud, Mari-Ann (2018). All-Oxide Thermoelectric Module with in Situ Formed Non-Rectifying Complex p-p-n Junction and Transverse Thermoelectric Effect. ACS Omega.  ISSN 2470-1343.  3(8), s 9899- 9906 . doi: 10.1021/acsomega.8b01357 Full text in Research Archive. Show summary

  All-oxide thermoelectric modules for energy harvesting are attractive due to high temperature stability, low cost, and the potential to use non-scarce and non-toxic elements. Thermoelectric modules are mostly fabricated in the conventional π-design, associated with the challenge of unstable metallic interconnects at high temperature. Here, we report on a novel approach to fabrication of a thermoelectric module with an in situ formed p-p-n junction made of state-of-the-art oxides Ca3Co4-xO9+δ (p-type) and CaMnO3-CaMn2O4 composite (n-type). The module was fabricated by spark plasma co-sintering of p- and n-type powders partly separated by insulating LaAlO3. Where the n- and p-type materials originally were in contact, a layer of p-type Ca3CoMnO6 was formed in situ. The hence formed p-p-n junction exhibited ohmic behavior and a transverse thermoelectric effect, boosting the open circuit voltage of the module. The performance of the module was characterized at 700 - 900 °C, with the highest power output of 5.7 mW (around 23 mW/cm2) at 900 °C and a temperature difference of 160 K. The thermoelectric properties of the p- and n-type materials were measured in the temperature range 100 - 900 °C, where the highest zT of 0.39 and 0.05 were obtained at 700 and 800 °C, respectively, for Ca3Co4-xO9+δ and the CaMnO3-CaMn2O4 composite.

• 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: 10.1016/j.ssi.2018.03.011 Full text in Research Archive. Show summary

  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.  20(4), s 2754- 2760 . doi: 10.1039/c7cp07471a Full text in Research Archive. Show summary

  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.

• Desissa, Temesgen D.; Schrade, Matthias & Norby, Truls Eivind (2018). Electrical Properties of a p–n Heterojunction of Li-Doped NiO and Al-Doped ZnO for Thermoelectrics. Journal of Electronic Materials.  ISSN 0361-5235.  47(9), s 5296- 5301 . doi: 10.1007/s11664-018-6394-3 Show summary

  The electrical properties of a p–n heterojunction of polycrystalline p-type Ni0.98Li0.02O and n-type Zn0.98Al0.02O have been investigated for potential applications in high-temperature oxide-based thermoelectric generators without metallic interconnects. Current–voltage characteristics of the junction were measured in a two-electrode setup in ambient air at 500–1000°C. The resistance and rectification of the junction decreased with increasing temperature. A non-ideal Shockley diode model was used to fit the measured current–voltage data in order to extract characteristic parameters of the junction, such as area specific series resistance Rs and parallel shunt resistance Rp, non-ideality factor, and the saturation current density. Rs and Rp decreased exponentially with temperature, with activation energies of 0.4 ± 0.1 eV and 1.1 ± 0.2 eV, respectively. The interface resistance of the direct p–n junction studied here is as such too high for practical applications in thermoelectrics. However, it is demonstrated that it can be reduced by an order of magnitude by using a composite of the individual materials at the interface, yielding a large effective contact area.

• Fleischer, Christian; Chatzitakis, Athanasios Eleftherios & Norby, Truls Eivind (2018). Intrinsic photoelectrocatalytic activity in oriented, photonic TiO2 nanotubes. Materials Science in Semiconductor Processing.  ISSN 1369-8001.  88, s 186- 191 . doi: 10.1016/j.mssp.2018.08.009 Show summary

  In this work, we grow oriented photonic TiO2 nanotubes (TNTs) with a well-established anodization method and their intrinsic catalytic and electronic properties are studied by means of (photo)electrochemical methods. The oriented photonic TNTs are assessed by the RctCdl (ΩF) product, which is a measure of the intrinsic photoelectrocatalytic activity (IPA) of the material. The RctCdl product decouples any surface area effects and it can be applied at any potential and accompanied reaction without knowing the actual electrochemically active surface area (EASA). Moreover, electrochemical impedance spectroscopy (EIS) is used in order to investigate the frequency dispersion in the single frequency Mott-Schottky (MS) measurement. The choice of frequency and the frequency dispersion in MS measurements in nanostructured and of high surface area semiconductors are rarely addressed and can result in erroneous values of two important parameters, i.e. flat band position and donor or acceptor densities. This work provides further insights into important electrochemical aspects and catalytic properties of high surface area nanomaterials for photoelectrochemical applications.

• Hancke, Ragnhild; Larsen, Thorbjørn V.; Xing, Wen; Li, Zuoan; Fontaine, Marie-Laure & Norby, Truls Eivind (2018). Ohmically heated ceramic asymmetric tubular membranes for gas separation. Journal of Membrane Science.  ISSN 0376-7388.  564, s 598- 604 . doi: 10.1016/j.memsci.2018.07.070
• 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(4), s 1592- 1599 . doi: 10.1016/j.jeurceramsoc.2017.11.011 Full text in Research Archive. Show summary

  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.

• Manabe, Ryo; Stub, Sindre Østby; Norby, Truls Eivind & Sekine, Yasushi (2018). Evaluating surface protonic transport on cerium oxide via electrochemical impedance spectroscopy measurement. Solid State Communications.  ISSN 0038-1098.  270, s 45- 49 . doi: 10.1016/j.ssc.2017.11.010
• Parras, J.P.; Genreith-Schriever, A.R.; Zhang, H.; Elm, M.T.; Norby, Truls Eivind & De Souza, R.A. (2018). Is ReO3 a mixed ionic-electronic conductor? A DFT study of defect formation and migration in a BVIO3 perovskite-type oxide. Physical Chemistry, Chemical Physics - PCCP.  ISSN 1463-9076.  20(12), s 8008- 8015 . doi: 10.1039/c7cp08214b
• Sood, Kapil; Kaswan, Jyoti; Singh, Surinder P.; Norby, Truls Eivind & Basu, Suddhasatwa (2018). Electrochemical and degradation study of Sr0.6Na0.4SiO3-δ. Journal of Solid State Electrochemistry.  ISSN 1432-8488.  22(10), s 3009- 3013 . doi: 10.1007/s10008-018-4007-y

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• Liu, Xin; Risbakk, Sanne; Almeida Carvalho, Patricia; Yang, Mingyi; Backe, Paul Hoff; Bjorås, Magnar; Norby, Truls Eivind & Chatzitakis, Athanasios Eleftherios (2020). Hydrogenase-assisted catalysis on titania electrode oxides. Show summary

  The widespread use of fuel cells and water splitting devices for energy generation and storage is limited by the dependence on noble metal catalysts. There is thus a tremendous need for the development of efficient electrocatalysts based on Earth-abundant elements. Nature inspired hydrogenases (HydA) are metallo-enzymes that catalyze the reversible reaction of H2 to protons and electrons. Hydrogenases containing Fe at the active sites, known as [FeFe]-HydA, show activities comparable to that of Pt. This work addresses a new class of electrodes for [FeFe]-HydA attachment and bio-assisted catalysis based on TiO2 nanotubes. The conducting oxide material provides suitable electronic conduction and hydrophilicity, while the nanostructure ensures tunability (tube length, crystal orientation and pore diameter) and high surface area for HydA attachment. In this work, electron microscopy is used to characterize the bio-electrodes. Based on the experimental findings, density functional theory (DFT) calculations are used to probe the catalytic reaction sites on the HydA and address the interaction between enzymes and TiO2. The novel bioelectrode will be employed in a system of artificial photosynthesis and generation of solar fuels by simultaneous water splitting and CO2 capture and utilization.

• Norby, Truls Eivind (2020). Electrodics for Protonics.
• Norby, Truls Eivind (2020). Electrodics for Protonics.
• Thøgersen, Annett; Diplas, Spyridon; Michel, Kathrin; Bjørheim, Tor Svendsen; Prytz, Øystein & Norby, Truls Eivind (2020). The surface of CeO2 unravelled.
• Xu, Kaiqi; Chatzitakis, Athanasios Eleftherios; Backe, Paul Hoff; Ruan, Qiushi; Tang, Junwang; Bjørås, Magnar; Rise, Frode & Norby, Truls Eivind (2020). The use of NMR to assess the activity of formate dehydrogenase biocatalysts for CO2 utilization.
• Bondevik, Tarjei; Prytz, Øystein & Norby, Truls Eivind (2019). Investigation of the electrostatic potential of a grain boundary in Y-substituted BaZrO3 using inline electron holography.
• Both, Kevin Gregor; Norby, Truls Eivind; Bjørheim, Tor Svendsen & Løvvik, Ole Martin (2019). Cu2O – ZnO p-n Junctions: Thermodynamics, Structure, and Properties – an Experimental and Theoretical Study.
• Dayaghi, Amir Masoud; Stange, Marit Synnøve Sæverud; Denonville, Christelle; Larring, Yngve; Rørvik, Per Martin; Haugsrud, Reidar & Norby, Truls Eivind (2019). Thin-film electrolyte with TEC optimized for metal-supported proton ceramic electrochemical cell.
• Frøen, Emil Herman; Norby, Truls Eivind; Bjørheim, Tor Svendsen & Løvvik, Ole Martin (2019). Coexistent Oxide p-n Junctions: DFT Analysis of Interfaces Between Nickel Oxide and Zinc Oxide.
• Kolding, Jonas; Norby, Truls Eivind; Sartori, Sabrina & Larring, Yngve (2019). Conductivity and Defects in Al-doped Li7La3Zr2O12 - A solid-state Li-ion conductor.
• Liu, Xin; Chatzitakis, Athanasios Eleftherios; Almeida Carvalho, Patricia; Risbakk, Sanne; Yang, Mingyi; Backe, Paul Hoff & Norby, Truls Eivind (2019). Enzyme-assisted Catalysis on Titania Electrodes.
• Norby, Truls Eivind (2019). Electrodics for proton ceramic electrochemical cells - positrodes.
• Norby, Truls Eivind (2019). Electrodics for protonics.
• Norby, Truls Eivind (2019). Ions and electrons at interfaces of functional ionic materials.
• Norby, Truls Eivind (2019). Novel aspects of electrocatalysis for hydrogen.
• Norby, Truls Eivind (2019). Proton ceramic electrochemical cells for efficient hydrogen production.
• Norby, Truls Eivind (2019). Role of surface protonics for electrodics.
• 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.

• Norby, Truls Eivind & Kalland, Liv-Elisif Queseth (2019). Protons in heavily doped CeO2 and related compounds.
• Norby, Truls Eivind; Kalland, Liv-Elisif Queseth; Løken, Andreas; Bjørheim, Tor Svendsen & Haugsrud, Reidar (2019). Hydration of fluorite-related rare-earth cerates.
• Norby, Truls Eivind; Liu, Xin; Bjørheim, Tor Svendsen & Haugsrud, Reidar (2019). Hydride ion conduction.
• Norby, Truls Eivind & Sun, Xinwei (2019). Hydrogen and clean air - Norway and China.
• Norby, Truls Eivind & Sun, Xinwei (2019). Novel UiO Technologies for Green Energy and Clean Air in China.
• Pedersen, Madeeha Khalid; Norby, Truls Eivind & Strandbakke, Ragnar (2019). Fundamentals of Positrodes for Proton Ceramic Electrochemical Cells.
• sata, noriko; han, feng; costa, remi; Zhou, Xingping; Stange, Marit Synnøve Sæverud; Dayaghi, Amir Masoud & Norby, Truls Eivind (2019). Development of Metal Supported Cells Using BaZrO3-Based Proton Conducting Ceramics.
• Stange, Marit Synnøve Sæverud; Dayaghi, Amir Masoud; Denonville, Christelle; Larring, Yngve; Rørvik, Per Martin; Haugsrud, Reidar & Norby, Truls Eivind (2019). Fabrication of Metal-Supported Proton-Conducting Electrolysers with Thin Film Sr- and Ce-Doped BZY Electrolyte.
• Stange, Marit Synnøve Sæverud; Dayaghi, Amir Masoud; Denonville, Christelle; Larring, Yngve; Rørvik, Per Martin; Haugsrud, Reidar & Norby, Truls Eivind (2019). Key challenges in fabrication of metal-supported thin film proton conducting electrolyser cells.
• Strandbakke, Ragnar; Balaguer, Maria; Wachowski, Sebastian Lech; Mielewczyk-Gryn, Aleksandra; Almeida Carvalho, Patricia; Sørby, Magnus Helgerud & Norby, Truls Eivind (2019). Protonics, stability and electrochemistry of Ba1‑xGd1-yLax+yCo2O6-δ (BGLC).
• Strandbakke, Ragnar; Bjørheim, Tor Svendsen; Sørby, Magnus Helgerud; Szpunar, Iga; Wachowski, Sebastian Lech; Mielewczyk-Gryn, Aleksandra; Balaguer, Maria; Almeida Carvalho, Patricia & Norby, Truls Eivind (2019). Protons in mixed conducting Ba1‑xGd1‑yLax+yCo2O6‑δ (BGLC).
• Strandbakke, Ragnar; Bjørheim, Tor Svendsen; Sørby, Magnus Helgerud; Wachowski, Sebastian Lech; Mielewczyk-Gryn, Aleksandra; Balaguer, Maria; Gunnæs, Anette Eleonora; Almeida Carvalho, Patricia & Norby, Truls Eivind (2019). Hydration and hydrogenation of mixed conducting BaGd1‑xLaxCo2O6‑δ (BGLC).
• Strandbakke, Ragnar; Bjørheim, Tor Svendsen; Vøllestad, Einar; Mielewczyk-Gryn, Aleksandra; Wachowski, Sebastian Lech; Lewandowska, Iga; Balaguer, Maria; 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.
• Sun, Xinwei; Chatzitakis, Athanasios Eleftherios & Norby, Truls Eivind (2019). Composite membranes for high temperature PEM fuel cells and electrolysers. Show summary

  Polymer electrolyte membrane(PEM) fuel cells and electrolysers offer efficient use and production of H2 for emission-free transport and sustainable energy systems. In order to reduce the cost,complexity,flooding,catalyst poisoning and degradation,operation above 80°C and at lower relative humidities(RH) is preferable. Acid doped polybenzimidazole(PBI),sulfonated polyetheretherketone(SPEEK) and their composites are being investigated for high temperature and low RH operation with sufficient conductivities. We take a critical view and a surface protonic approach to gain fundamental insight.

• Sun, Xinwei; Chatzitakis, Athanasios Eleftherios & Norby, Truls Eivind (2019). Polymer-ceramic composite membranes for intermediate temperature PEM fuel cells.
• Sun, Xinwei & Norby, Truls Eivind (2019). Hydrogen og hydrogenteknologi.
• Vijayan Sobhana, Dilimon; Xing, Wen & Norby, Truls Eivind (2019). Electrode reactions on a molten carbonate Gd-doped CeO2 composite electrolyte. Show summary

  The complex chemical and electrochemical reactions involving CO2 and O2 at the cathode generally determine the overall performance of molten carbonate fuel cells (MCFCs) [1,2]. Experimental reports on the cathodic reactions consider merely the ions in the bulk molten carbonate (e.g. peroxide, superoxide, and peroxycarbonate ions, in addition to carbonate ions). Recently Czelej et al. used DFT calculations to investigate the MCFC cathode reactions at the perimeter of a triple phase boundary (TPB) of electronically conducting NiO, ionically conducting molten electrolyte, and pore space with reactant gases [1,2]. They showed a sequential Mars-van Krevelen and Eley-Rideal mechanism involving cathodic transformation of CO2 to CO32- via direct interaction of CO2 with the O-terminated octopolar NiO(111). Electrode reactions on a composite electrolyte with molten carbonate and ceramic oxide ion conductor have so far not been studied, however. In the present work, Gd-doped ceria (GDC) based composite membranes prepared by infiltration of Li2CO3-Na2CO3 eutectic molten phase in a pre-sintered porous GDC matrix were studied in the temperature range 575–675oC by electrochemical impedance spectroscopy (EIS) to characterize electrode reactions on them. A symmetrical cell configuration comprising two painted porous gold electrodes was used for the study. Three time constants associated with electrode processses were identified. The slowest process, with an activation energy of 130 kJ/mol showed a positive partial pressure dependency of exchange current density for O2, whereas the dependency was negative for CO2. Possible mechanisms are derived and discussed. References 1. K. Czelej et al., J. Mater. Chem. A 5 (2017) 13763-13768. 2. K. Czelej et al., Appl. Catal. B 222 (2018) 73–75.

• Vøllestad, Einar; Sørby, Magnus Helgerud & Norby, Truls Eivind (2019). Defect chemistry of mixed conducting double perovskites.
• Xu, Kaiqi; Chatzitakis, Athanasios Eleftherios; Norby, Truls Eivind & Bjørheim, Tor Svendsen (2019). Ta3N5 nanotubes loaded with Co(OH)x/Co-Pi-high photocurrent densities and improved photocorrosion resistance.
• Xu, Kaiqi; Grandcolas, Mathieu; Yang, Juan; Mei, Sen; Chatzitakis, Athanasios Eleftherios & Norby, Truls Eivind (2019). Photoelectrochemical water splitting on Ta3N5 nanotubes for H2 production.
• Balaguer, Maria; Tarach, Mateusz; Strandbakke, Ragnar; Bjørheim, Tor Svendsen; Mielewczyk-Gryn, Aleksandra; Wachowski, Sebastian; Lewandowska, Iga; Sørby, Magnus Helgerud; Gazda, Maria; Norby, Truls Eivind & Serra, José Manuel (2018). Hydration Stability of Mixed Conducting Layered Oxides.
• Bondevik, Tarjei; Norby, Truls Eivind & Bjørheim, Tor Svendsen (2018). Validating approximations commonly used in space charge modelling.
• Chatzitakis, Athanasios Eleftherios; Simonsen, Stian; Fontaine, Marie Laure; Thomassen, Magnus & Norby, Truls Eivind (2018). Conductivity of polymer-ceramic composite membranes at high T and p(H2O) using a novel PEEK sample holder.
• Clark, Daniel Ryan; Malerød-Fjeld, Harald; Budd, Michael; Catalán-Martinez, David; Beeaff, Dustin; Norby, Truls Eivind & Haugsrud, Reidar (2018). Design and development of next-generation protonic reactors.
• Dayaghi, Amir Masoud; Stange, Marit Synnøve Sæverud; Denonville, Christelle; Larring, Yngve; Rørvik, Per Martin & Norby, Truls Eivind (2018). Key challenges in fabrication of metal-supported proton conducting electrolyser cells.
• Desissa, Temesgen D.; Norby, Truls Eivind & Haugsrud, Reidar (2018). Stability and properties of materials and interfaces for oxide thermoelectrics. Series of dissertations submitted to the Faculty of Mathematics and Natural Sciences, University of Oslo.. 1969.
• Emhjellen, Linn Katinka; Bjørheim, Tor Svendsen; Fontaine, Marie-Laure; Li, Zuoan & Norby, Truls Eivind (2018). Novel Molten/solid Oxygen Transport Membranes for CO2 Capture.
• Fleischer, Christian; Bjørheim, Tor Svendsen & Norby, Truls Eivind (2018). Point Defects in Transition Metal Dichalcogenides. Show summary

  Defect chemistry has given the possibility to control and tune properties to obtain better functional bulk materials. In comparison, and despite the recent interest and prospects of twodimensional materials, their defect chemistry remains mainly unexplored. We believe that an understanding of the influence of the dielectric environment on the defect chemistry and properties is crucial for further developing new and superior 2D materials. Here, we present results from our computational work on selected point defects in monolayer MoS2. Investigated defects comprises molybdenum and sulphur vacancies in addition to hydrosulfide on sulphur site.

• Fleischer, Christian; Bjørheim, Tor Svendsen; Polfus, Jonathan M. & Norby, Truls Eivind (2018). Point Defects in Monolayer MoS2.
• Fleischer, Christian; Polfus, Jonathan M.; Bjørheim, Tor Svendsen & Norby, Truls Eivind (2018). Defect Chemistry of Few- and Monolayer MoS2. Show summary

  Defect chemistry has given the possibility to control and tune properties to obtain better functional bulk materials. In comparison, and despite the recent interest and prospects of two-dimensional materials, their defect chemistry remains mainly unexplored. We believe that an understanding of the influence of the dielectric environment on the defect chemistry and properties is crucial for further developing new and superior 2D materials. Here, we present results for molybdenum disulphide (MoS2) films on Si/SiO2 substrates. Methods comprise magnetron sputtering of Mo with subsequent annealing in H2S atmosphere and the chemical vapour transport method. The films and defects are characterised by AFM, XPS, photoluminescence, optical microscopy and Raman spectroscopy in addition to electrical measurements in controlled atmospheres. Ab initio computations on a variety of point defects and defect clusters further elucidate the defect chemistry.

• Fontaine, Marie-Laure; Chatzitakis, Athanasios Eleftherios; Vøllestad, Einar; Thomassen, Magnus & Norby, Truls Eivind (2018). Principles of proton conduction in polymer-ceramic composite membranes for PEM applications.
• Grandcolas, Mathieu; Wabende, Brian; Yang, Juan; Mei, Sen; Xu, Kaiqi; Chatzitakis, Athanasios Eleftherios & Norby, Truls Eivind (2018). TiO2 Nanorods Decorated With Cobalt oxide as Photoanodes for a Bio-Hybrid PEC Cell.
• Hu, Yang & Norby, Truls Eivind (2018). La-SrTiO3 point-contact electrode on proton conducting BaZr0.85Y0.15O3-δ.
• Lukaszuk, Katarzyna Anna; Carretero, Isabel Díaz; Louis, Benoit & Norby, Truls Eivind (2018). Controlling the morphology of zeolite crystals in OFF and MTT/TON systems. Series of dissertations submitted to the Faculty of Mathematics and Natural Sciences, University of Oslo.. 2038.
• Ma, Quanbao; Ibishi, Diamanta & Norby, Truls Eivind (2018). Preparation and characterization of Ru/CeO2 catalysts for electrically enhanced ammonia synthesis.
• Norby, Truls Eivind (2018). Dekarbonisering - henger Norge med?.
• Norby, Truls Eivind (2018). Electrodics for proton ceramic electrochemical cells.
• Norby, Truls Eivind (2018). Electrodics for proton ceramic electrochemical cells (PCECs).
• Norby, Truls Eivind (2018). Hydrogen (prisforedrag for Guldberg-Waage-medaljen 2018). Show summary

  Starting my first research in inorganic chemistry, I stumbled across hydrogen where and when I and everyone else did not expect to find it – it is so common and yet so un-common. It makes bonds more different than any other element – polar and purely covalent as protons and atoms, metallic when it pleases, and ionic as hydride ions. Consequently, it shows up in very different forms and locations and has taken me for a journey to my roots in physical chemistry and to electrochemistry – some things discovered and some mysteries remaining. Hydrogen holds a historical role in the establishment of major Norwegian industry, and we today host world-leading production of electrolyzers for the emerging markets of hydrogen for storage and as carrier of renewable electrical energy. Many different types of solids contain or may take up water and become solid-state proton conductors by various mechanisms of transport. They may be used as electrolytes in novel types of fuel cells and electrolyzers for hydrogen and renewable energy, as well as in electrocatalytic reactors for upgrading natural gas to liquids or hydrogen with minimal carbon emissions or with carbon capture and storage. The research involves experimental and ab initio computational methods to understand hydrogen in its various forms from gas phase, via surfaces and charge transfer at electrode interfaces, into mobile ions in crystalline or liquid-like condensed phases.

• Norby, Truls Eivind (2018). Proton ceramic cells for fuel cells, electrolyzers, and natural gas conversion.
• Norby, Truls Eivind (2018). Proton ceramics.
• Norby, Truls Eivind (2018). The chemistries of proton ceramic electrochemical cells.
• Norby, Truls Eivind; Min, Chen & Bondevik, Tarjei (2018). Space-charge and its effects on solid-oxide electrode kinetics.
• Norby, Truls Eivind; Min, Chen; Bondevik, Tarjei & Polfus, Jonathan M. (2018). Space Charge Layers and Their Role for Properties of Interfaces in Solid State Ionics.
• Stange, Marit Synnøve Sæverud; Dayaghi, Amir Masoud; Denonville, Christelle; Rørvik, Per Martin; Larring, Yngve & Norby, Truls Eivind (2018). Fabrication of Metal Supported Protonic Ceramic Electrolyser Cells (PCEC).

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