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The perovskite CaCu3Ti4O12is known for its ability to photocatalytically degrade model dye molecules using visible light. The influence of ball milling preformed CaCu3Ti4O12on the catalysts structure and performance in the degradation of rhodamine B and the antihistamine cetirizine hydrochloride, which does not absorb light in the visible region, was investigated. The surface area of CaCu3Ti4O12increased from 1 m2g−1to >80 m2g−1on milling with a retention of 96% CaCu3Ti4O12phase purity, as determined by X-ray diffraction and extended X-ray absorption fine structure analysis. Multiple characterisation techniques showed an increase in structural defects on milling, including, for the first time, X-ray absorption near edge spectroscopy which showed changes in the local electronic structure from the perspective of Cu and Ti. Photocatalytic degradation was notably higher with the milled sample than that observed for the as-synthesized sample, even after normalisation for surface area, with a doubling of surface normalised rate constant from 4.91 × 10−4to 9.11 × 10−4L min−1m2for rhodamine B degradation and a tripling for cetirizine hydrochloride degradation from 2.64 × 10−4to 7.92 × 10−4L min −1m−2. The improvement in catalytic performance can be correlated to the defects observed by X-ray absorption spectroscopy.

This work describes the development of electroconductive hydrogels as injectable matrices for neural tissue regeneration by exploiting a biocompatible conductive polymer – poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) – combined with a biomimetic polymer network made of gelatin. Our approach involved also genipin – a natural cross-linking agent – to promote gelation of gelatin networks embedding PEDOT:PSS. The achieved results suggest that physical–chemical properties of the resulting hydrogels, like impedance, gelation time, mechanical properties, swelling and degradation in physiological conditions, can be finely tuned by the amount of PEDOT:PSS and genipin used in the formulation. Furthermore, the presence of PEDOT:PSS (i) enhances the electrical conductivity, (ii) improves the shear modulus of the resulting hydrogels though (iii) partially impairing their resistance to shear deformation, (iv) reduces gelation time and (v) reduces their swelling ability in physiological medium. Additionally, the resulting electroconductive hydrogels demonstrate enhanced adhesion and growth of primary rat cortical astrocytes. Given the permissive interaction of hydrogels with primary astrocytes, the presented biomimetic, electroconductive and injectable hydrogels display potential applications as minimally invasive systems for neurological therapies and damaged brain tissue repair.

Ceramic membranes operating at high-temperatures are a key-technology for hydrogen separation processes. Cer-cer composites based on BaCe0.65Zr0.20Y0.15O3-δ-Gd0.2Ce0.8O2-δhave gained increasing attention as asymmetric membranes for H2purification, for their high proton-electron conductivity, 100% selectivity, temperature and chemical stability, and intrinsic lower costs compared with the Pd–based technologies. Here, BCZY-GDC composite parts were successfully fabricated for the first time by microextrusion. Water-based pastes with different solid loadings and suitable rheological properties were formulated and printed in single or multilayer structures without nozzle clogging. After deposition, the samples were osmotically dried in concentrated PEG solutions in order to obtain cracks-free green bodies. The further process optimization allowed the production of planar BCZY-GDC ceramics to be potentially applied in asymmetric membrane structures. The mechanical properties of the as-obtained single and multilayer structures as well as of the interface between filaments were assessed through different nanoindentation techniques.

Nowadays, reducing carbon dioxide emission in the atmosphere is one of the most important environmental issues that must be overcome. At the same time, low-cost and environmentally friendly technologies are necessary to produce renewable fuels able to replace the conventional fossil ones. Electrochemical cells (driven by solar energy) and photo-electrochemical cells (PECs) are among the main efficient technologies to get these challenging goals. Taking into account the PEC working mechanism, two different electrodes, based on photo-electrocatalytic and electrocatalytic materials able to drive reactions both under illumination or in dark conditions, are involved. In this review, recent results on carbon-based materials for electrocatalytic and photo-electrocatalytic carbon dioxide reduction are discussed. The properties and synthesis conditions applied to the preparation of conducting polymer and graphitic carbon nitride (g-C3N4) are described and discussed for their application in the photoactive electrodes. As for the electrodes to be applied in the electrocatalytic CO2activation and conversion, light heteroelement-doped carbon nanomaterials have been taken into account as highly valuable metal-free candidate to run the process efficiently and selectively. For the latter process, also the influence of the electrolyte and the selectivity towards different reaction products will be discussed. All these data taken together indicate that a lot of work still has to be done to achieve high efficiency with metal-free organic-based electro- and photo-electrocatalysts applied to the carbon dioxide conversion. Anyhow, many seminal outcomes collected in the literature up to now clearly indicate the real possibility to replace highly costly metal-based materials with simply organic ones.

Steam electrolysis by means of reversible Fuel Cells is a promising concept for compensating the intermittency of renewable energy sources. Several tests on SOFC stacks operated in reverse mode (SOEC) reported faster degradation than in power production mode. Although not completely clarified, the degradation mechanisms appear partly related to the higher steam concentration at the electrode compartments. This work introduces a novel type of cell with dual anionic-protonic conductivity, which allows the separation of the steam compartment from the electrodes compartments. The concept is presented together with a set of experimental results pointing out the potential advantages of this approach.

Whereas significant advances have been reported in the performances of solid oxide fuel cells, some work has still to be done to reduce the costs connected to the overall processing of these systems. Tape casting and screen-printing are the most common techniques used for the fabrication of large area SOFCs. The production of the bilayer anode-electrolyte entirely by tape casting, or by tape casting coupled with screen-printing, are two of the most economical and reliable shaping alternatives. The work presents two unconventional approaches to these techniques applied to the production of anode-supported half-cell (NiOGDC/GDC), namely the use of water-based screen printing inks and an innovative lamination process done at room temperature and low pressure. These variations of the common multilayer production scheme, potentially allow overcoming two of the drawbacks connected with them: the use of organics for the production of screen printing inks and high temperature or glues for the lamination of tapes. Both approaches allowed producing crack-free large area half cells with dense GDC electrolyte.

The production of planar, anode-supported half-cell with suitable morphological characteristics needs a careful control of the thermal treatments involved. Although the thermal profiles are generally well analyzed in literature, the role played by the setter plates on the half-cell manufacturing is generally neglected although they can strongly affect the final results. In this study the influence of the nature of setter plates in the production of large area NiO-YSZ/YSZ half cells was deeply investigated. In particular the performance and the possible interaction of the SiC, alumina and zirconia setter plates with the half-cell during the sintering stage were thoroughly evaluated in order to assess the best thermal set-up.

From neutron diffraction it is known that the BaCeO3 perovskite undergoes a sequence of phase transformations from high temperature cubic C to rhombohedral R, to orthorhombic O1 (Imma) and to orthorhombic O2 (Pnma). Doping Y3+ on the Ce4+ site introduces charge compensating O vacancies (VO) that may be partially filled with OH complexes with exposition to H2O, so making the material an ionic conductor. Anelastic relaxation experiments have been carried out on samples doped with 2%Y and 10%Y; the real part s’(T) of the complex elastic compliance presents softenings at the transitions, and the loss s’’/s’ curves allow the content of VO and H to be monitored. Doping has a strong effect on the temperature of the Pnma/R transition: with 10%Y in the fully hydrated state TO1-R increases up to 750 K while after full outgassing falls to 500 K, meaning that the introduction of ~5% VO shifts the transition of 250 K. While the effect of cation substitution on the transitions temperature is easily explained in terms of simple arguments usually valid for perovskites based on bond length considerations, the remarkable stabilization of the R phase by VO requires to take into account the anomalous sequence of phase transitions of undoped BaCeO3, where the R structure transforms into orthorhombic Pnma on cooling with the loss of an octahedral tilt system.

BaCe0.65Zr0.2Y0.15O3-d (BCZY) have been recently proposed for IT-SOFCs due to its high proton conductivity. On the other hand considerable efforts are directed towards the development of metal-supported cells. The combination of the potential advantages offered by either proton conductors based cells and metal supported configuration has never been explored. In this work the technological issues to produce proton conducting BCZY-Ni anodes stainless steel-supported were carefully investigated. A tailored porous metal support was produced by tape casting. Afterwards the anode was deposited by screen printing and the resulting bilayer sintered in reducing atmosphere. Each step of the production process was thoroughly investigated. A cations interdiffusion between the metallic support and the anodic layer was observed in all range of temperatures considered. The influence of a CeO2 barrier layer and anode thickness on the cations diffusion and a successful production of planar crack-free anode was deeply analyzed.

Yb:Y2O3submicrometric particles were synthesized through co‐precipitation of Yb and Y nitrate in water. Microwave heating and controlled release of ammonia through urea decomposition at reaction temperature leaded to the formation of disaggregated, monosized spherical particles of carbo‐hydroxy‐nitrate precursors. Pure crystalline Yb:Y2O3powder that preserved the described morphology was obtained after calcination in air at 800 °C for 30 min. This powder mixed with commercial alumina powder was used to produce transparent Yb:YAG ceramics. Improved properties in terms of powder morphology and reactivity were presented in comparison with powders obtained by traditional heating.

Gadolinia-doped ceria (Ce0.8Gd0.2O2-d, GDC) is an alternative electrolyte for Intermediate Temperature Solid Oxide Fuel Cells (IT-SOFC). Nanostructured materials have recently attracted extensive attention because of their high reactivity that allowed milder sintering conditions. Although several methods were proposed for the synthesis of ultrafine powders, most of them generally require a subsequent calcination step. The aim of this work was to produce ultrafine, pure GDC powders using a standard chemical route (aqueous sol-gel) coupled with non-conventional heating processes (infrared heating). Nanocrystalline non-agglomerated GDC particles were successfully produced under mild conditions (170{degree sign}C, 1h) without the intermediate decomposition and/or calcining steps. Moreover the GDC obtained through the optimization of the IR-assisted sol-gel synthesis parameters exhibited values of ionic conductivity higher than the ones showed by commercial and conventional sol-gel produced powders of similar composition.

Solid oxide fuel cell technology offers substantial advantages for clean and efficient power generation. However, the high working temperatures impose severe restrictions on the materials selection. The key to prolong the stack lifetime, widen the selection of materials and reduce the costs lies in lowering the working temperature. Two main approaches have been applied for this purpose: testing materials based on Gd doped CeO2, having higher ionic conductivity at lower temperatures, and decreasing the electrolyte thickness. At present, different methods have been studied for the deposition of fully dense thin coatings. Among them, the radio frequency magnetron sputtering technique is a powerful and versatile tool to deposit mixed oxide thin films in a wide thickness range (100 nm/10 um). In this report, the results about the deposition by RF magnetron sputtering of 1/5 um GDC films on anodic substrates will be presented.

This study reports the effect of copper oxide on the sintering mechanism of Ce0.8Gd0.2O2-d (GDC) studied through dilatometric and microstructural analyses. The addition of 3% CuO into GDC greatly improves its sinterability lowering the sintering temperature of more than 300{degree sign}C and increasing its maximum shrinkage rate. The early-stage sintering has been modeled showing a mechanism substantially different from the one generally accepted for CoO.

Further cost reductions are necessary for the commercialization of solid oxide fuel cells (SOFCs). The economically sensible methods of screen-printing and tape casting were used to fabricate green films that were subsequently sintered producing 5 cm x 5 cm planar Yittria- stabilized-Zirconia (YSZ)-based SOFCs. An anode-interlayer was also included in the cell design that increased interfacial bonding between the electrolyte and anode. The SOFCs were characterized using scanning electron microscopy and pressure drop measurements. The YSZ electrolytes were gas- tight and dense. These cells showed a maximum power density of 0.14 W/cm2 when tested using a methane-water vapor fuel source at 800{degree sign}C.

Solid Oxide Fuel Cells have still many technical problems related to its high operating temperature (800–1000 °C). The most recent studies deal with reducing the operation temperature increasing at the same time the durability of the device. The use of La0.8Sr0.2Ga0.8Mg0.2O3-δ(LSGM) perovskite as electrolyte, could be a very promising solution for IT-SOFC operating at 600°C. In this work, LSGM bilayers constituted by a thicker porous layer (namely the anode scaffold) and a dense electrolyte were produced by tape casting. The critical issues to obtain flexible and crack-free green tapes suitable for lamination were carefully examined. In particular, the nature and amount of pore former needed to obtain an anode scaffold with a porous network suitable for the catalysts impregnation process were deeply investigated.

In this paper we present the combine modeling and experimental study of electrochemical hydrogen oxidation at an alternative perovskite based mixed-conducting SOFC anode. Two types of button cells without and with addition of nickel (Ni) were fabricated based on La0.1Sr0.9TiO3-α(LST)-CGO composite anodes and dense YSZ electrolytes. Electrochemical experiments were performed using symmetrical cell configuration in H2/H2O fuel mixture systematically varying applied potentials and operating temperatures. The previously developed model, which includes thermal chemistry at each surface, charge-transfer processes and reactive porous media transport, was employed. It was found that in the case of conventional LST based anodes heterogeneous and charge transfer chemistry at LST surface has capacitive behavior and alters the impedance spectra. However, if nickel is added the influence of LST surface chemistry is diminished leading to an improvement of cell performance.

The present paper refers to an innovative SOFC concept named EVOLVE after a running FP7 project which integrates advanced materials and an inventive anode current collector made from a NiCrAl preoxidized foam impregnated with a conductive perovskite. Even if the concept is the beneficial combination of Metal supported cell (MSC) and Anode supported cell (ASC) technologies, strong improvements in terms of reliability and durability are expected. In order to enhance anode efficiency, the 3D microstructure needs to be precisely described at the microscopic scale. ISTEC has produced LST-GDC active anode layers using screen printing process. Back-scattered electrons (BSE) SEM images that contain relevant microstructure information have been realized by Centre des Matériaux. All the original images have been enhanced by Centre de Morphologie Mathématique using a series of morphological operators to remove artefacts. Finally, a 3D pluri-Gaussian model has been generated from 2D images, and then computed to predict volume fraction of the 3 phases, 3D tortuosity, gas permeation and ionic conductivities.

The production of planar, anode-supported half-cell with suitable morphological characteristics needs a careful control of the thermal treatments involved. Although the thermal profiles are generally well analyzed in literature, the role played by the setter plates on the half-cell manufacturing is generally neglected although they can strongly affect the final results. In this study the influence of the nature of setter plates in the production of large area NiO-YSZ/YSZ half cells was deeply investigated. In particular the performance and the possible interaction of the SiC, alumina and zirconia setter plates with the half-cell during the sintering stage were thoroughly evaluated in order to assess the best thermal set-up.

Whereas significant advances have been reported in the performances of solid oxide fuel cells, some work has still to be done to reduce the costs connected to the overall processing of these systems. Tape casting and screen-printing are the most common techniques used for the fabrication of large area SOFCs. The production of the bilayer anode-electrolyte entirely by tape casting, or by tape casting coupled with screen-printing, are two of the most economical and reliable shaping alternatives. The work presents two unconventional approaches to these techniques applied to the production of anode-supported half-cell (NiOGDC/GDC), namely the use of water-based screen printing inks and an innovative lamination process done at room temperature and low pressure. These variations of the common multilayer production scheme, potentially allow overcoming two of the drawbacks connected with them: the use of organics for the production of screen printing inks and high temperature or glues for the lamination of tapes. Both approaches allowed producing crack-free large area half cells with dense GDC electrolyte.

Steam electrolysis by means of reversible Fuel Cells is a promising concept for compensating the intermittency of renewable energy sources. Several tests on SOFC stacks operated in reverse mode (SOEC) reported faster degradation than in power production mode. Although not completely clarified, the degradation mechanisms appear partly related to the higher steam concentration at the electrode compartments. This work introduces a novel type of cell with dual anionic-protonic conductivity, which allows the separation of the steam compartment from the electrodes compartments. The concept is presented together with a set of experimental results pointing out the potential advantages of this approach.

BaCe0.65Zr0.2Y0.15O3-δ (BCZY) have been recently proposed for IT-SOFCs due to its high proton conductivity. On the other hand considerable efforts are directed towards the development of metal-supported cells. The combination of the potential advantages offered by either proton conductors based cells and metal supported configuration has never been explored. In this work the technological issues to produce proton conducting BCZY-Ni anodes stainless steel-supported were carefully investigated. A tailored porous metal support was produced by tape casting. Afterwards the anode was deposited by screen printing and the resulting bilayer sintered in reducing atmosphere. Each step of the production process was thoroughly investigated. A cations interdiffusion between the metallic support and the anodic layer was observed in all range of temperatures considered. The influence of a CeO2 barrier layer and anode thickness on the cations diffusion and a successful production of planar crack-free anode was deeply analyzed.

Gadolina doped ceria (GDC) is a promising electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFC). Dense layers of this material can be economically deposited by screen printing. However, the inks for this technique generally use organic compounds that can raise health and safety issues, as well as economical issues. In order to obtain a low-cost alternative to the generally accepted organic-based ink, four different blends of binders were considered to prepare water-based GDC inks. The systems were deposited onto green NiO/GDC anodes produced by tape casting and treated at 1673 K for 4 h. By choosing the right combination of solvents and binders, it was possible to obtain a dense crack-free film of GDC from a water-based system.

Gadolina doped ceria (GDC) is a promising electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFC). Dense layers of this material can be economically deposited by screen printing. However, the inks for this technique generally use organic compounds that can raise health and safety issues, as well as economical issues. In order to obtain a low-cost alternative to the generally accepted organic-based ink, four different blends of binders were considered to prepare water-based GDC inks. The systems were deposited onto green NiO/GDC anodes produced by tape casting and treated at 1673 K for 4 h. By choosing the right combination of solvents and binders, it was possible to obtain a dense crack-free film of GDC from a water-based system.

Gadolinia-doped ceria (Ce0.8Gd0.2O2-δ, GDC) is an alternative electrolyte for Intermediate Temperature Solid Oxide Fuel Cells (IT-SOFC). Nanostructured materials have recently attracted extensive attention because of their high reactivity that allowed milder sintering conditions. Although several methods were proposed for the synthesis of ultrafine powders, most of them generally require a subsequent calcination step. The aim of this work was to produce ultrafine, pure GDC powders using a standard chemical route (aqueous sol-gel) coupled with non-conventional heating processes (infrared heating). Nanocrystalline non-agglomerated GDC particles were successfully produced under mild conditions (170{degree sign}C, 1h) without the intermediate decomposition and/or calcining steps. Moreover the GDC obtained through the optimization of the IR-assisted sol-gel synthesis parameters exhibited values of ionic conductivity higher than the ones showed by commercial and conventional sol-gel produced powders of similar composition.

Solid oxide fuel cell technology offers substantial advantages for clean and efficient power generation. However, the high working temperatures impose severe restrictions on the materials selection. The key to prolong the stack lifetime, widen the selection of materials and reduce the costs lies in lowering the working temperature. Two main approaches have been applied for this purpose: testing materials based on Gd doped CeO2, having higher ionic conductivity at lower temperatures, and decreasing the electrolyte thickness. At present, different methods have been studied for the deposition of fully dense thin coatings. Among them, the radio frequency magnetron sputtering technique is a powerful and versatile tool to deposit mixed oxide thin films in a wide thickness range (100 nm÷10 μm). In this report, the results about the deposition by RF magnetron sputtering of 1÷5 μm GDC films on anodic substrates will be presented.

This study reports the effect of copper oxide on the sintering mechanism of Ce0.8Gd0.2O2-δ (GDC) studied through dilatometric and microstructural analyses. The addition of 3% CuO into GDC greatly improves its sinterability lowering the sintering temperature of more than 300{degree sign}C and increasing its maximum shrinkage rate. The early-stage sintering has been modeled showing a mechanism substantially different from the one generally accepted for CoO.

Further cost reductions are necessary for the commercialization of solid oxide fuel cells (SOFCs). The economically sensible methods of screen-printing and tape casting were used to fabricate green films that were subsequently sintered producing 5 cm x 5 cm planar Yittria- stabilized-Zirconia (YSZ)-based SOFCs. An anode-interlayer was also included in the cell design that increased interfacial bonding between the electrolyte and anode. The SOFCs were characterized using scanning electron microscopy and pressure drop measurements. The YSZ electrolytes were gas- tight and dense. These cells showed a maximum power density of 0.14 W/cm2 when tested using a methane-water vapor fuel source at 800{degree sign}C.