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The tailoring of multi-tasking perovskite oxide-based electrodes for solid oxide cells has shown growing interest. The development of flexible structures represents a crucial step towards the design of symmetric and possibly SOFC/SOEC reversible systems. In this work, low (0.5 mol%) B-site Pt-doping in a lanthanum strontium ferrite is presented as a successful approach to enhance the parent perovskite properties as both SOC air and fuel electrode. Structural, morphological and electrochemical characterizations of La0.6Sr0.4Fe0.995Pt0.005O3-δ (LSFPt005) are provided and compared to the undoped compound. LSFPt005-symmetric devices are tested as CO-SOFCs and CO2-SOECs at 850 °C, respectively, obtaining a maximum power density of 301 mW/cm2 and a current density of 0.82 A/cm2 at 1.5 V. Insights of cell operating mechanisms are provided through electrochemical impedance spectroscopy.

Solid oxide fuel cells (SOFCs) have a great potential among the emerging energy conversion technologies because they can efficiently convert various types of fuel (hydrogen, methane, CO, biogas) into electrical energy in the 750-850 °C temperature range. The choice of electrodes remains a challenge because most metal oxides suffer from low chemical stability and low electrocatalytic activity toward oxygen reduction reaction (ORR) in the intermediate temperatures (IT) range (500-700 °C) [1]. In this view, perovskite oxides (ABO3) have shown excellent properties in terms of thermal stability, compatibility with other cell components, low production cost and, most importantly, great flexibility [1]. La0.6Sr0.4FeO3-δ, (LSF) perovskite oxide have been widely investigated for the high electrical conductivity and the electrochemical properties [2]. However, the main drawback is the poor activity towards ORR in the IT range, as most iron-based perovskite oxides [3]. The B-site doping with noble metal catalysts can sensitively improve the properties and make the compounds suitable for electrode application. The addition of small amounts of Ru or Pt into LSF structure can be an effective approach to improve the electrocatalytic properties [4,5]. Specifically, we synthesized B-site doped LSF powders with very low amounts (15 m2/g). All compounds showed a single perovskite phase. As reported in Fig. (a), the addition of Ru and Pt in the structure causes a progressive shift of the XRD peaks to lower 2θ angles indicating the perovskite lattice expansion due to the substitution of Fe4+/ Fe3+ sites with larger Ru and Pt ions. To assess the electrocatalytic activity, the compounds were investigated in oxidizing conditions using electrochemical impedance spectroscopy (EIS) analysis. Fig. (b) shows the Arrhenius plot of area specific resistance (ASR) values of LSFRu and LSFPt perovskite oxides. The ASR values were measured on LSFM/La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM)/LSFM (M=Ru, Pt) symmetric cells in the temperature range 550-800 °C. The insertion of a very low amount (1%mol) of Pt or Ru significantly reduces the polarization resistance, confirming the beneficial effect of noble metal ions on ORR activity. All these features suggest that very low Pt and Ru doping positively affects the structural and electrocatalytic properties valuably for cathodic applications. [1] Hwang J, Rao R.R. (2017). Science 358:751-756 [2] Hansen KK, Mogensen M (2008). ECS Trans 13:153–160 [3] Chavan SV, Singh RN (2013). J Mater Sci 48:6597–6604 [4] Fan W, Sun Z. (2016) RSC Adv 6:34564 [5]Shaoli G., Hongjing Wu, (2015),Catalysts, 5, 366-391 Figure 1

Tungsten carbide (WC) is the most important tungsten compound, and the main component of WC-Co cermet composites. WC-Co are widely used engineering materials due to the combination of high hardness and strength of tungsten carbide with the toughness and plasticity of the metallic binder. The direct synthesis of WC from tungsten concentrate containing ∼70% WO3 has been achieved by carbothermic reduction. Mineral/carbon black mixtures were prepared by planetary ball milling and subjected to annealing at 1150 °C in flowing Ar. Specific leaching treatments have been developed to remove foreign phases and obtain pure WC powders. This new process allows about 50% energy saving, -34% CO2 emissions, and significantly lower amounts of industrial waste, with respect to the classical hydrometallurgical tungsten extraction and subsequent pyrometallurgical WC synthesis, widely used in tungsten industry. WC powders obtained by carbothermic reduction of the mineral were employed to prepare sintered WC-8 wt %Co samples that showed high density (>99%), hardness (1490 HV), and toughness (14.6 MPa·m1/2). These findings demonstrate, for the first time, that the carbothermic reduction of tungsten concentrates does represent a viable process for energy efficient and sustainable synthesis of WC powders to be used in the production of cemented carbides.

Reversible solid oxide cell (RSOC) technology allows use of a single device to efficiently derive chemicals from power (power-to-fuel) and power from chemicals (fuel-to-power). Fuel flexibility is a key aspect, as developing SOCs able to operate on fuels other than hydrogen can ease their integration into existing infrastructure. In addition, H2O and/or CO2 reduction is favorable in SOECs as polarization losses are reduced at high temperature. Here, a composite fuel electrode, 60 wt.% La0.6Sr0.4Fe0.8Mn0.2O3-δ (LSFMn) and 40 wt.% (5 wt.% Ni)-containing Ce0.85Sm0.15O2-δ (Ni-SDC) was investigated in H2-fueled, CO-fueled SOFCs and for CO2 reduction in SOEC mode. In reducing conditions, Fe exsolved from the LSFMn perovskite formed a Ni-Fe alloy with Ni present on SDC. The composite fuel electrode showed remarkable activity for CO2 reduction with a current density output of 1.40 A cm-2 (1.5 V) at 850 °C. SOFC/SOEC cell reversibility was obtained in different CO2:CO mixtures. Electrochemical impedance spectroscopy analysis was used to better understand cell mechanisms in SOFC and SOEC mode.

Thermal energy storage technology with Phase Change Materials (PCM) is an attractive option to optimise energy resources and to recover and promote excess heat. The phase change behaviour of PCM requires advanced research to understand and better control the thermal energy storage using PCM, which is a crucial step to develop a powerful latent storage system. This paper aims to analyse the multiphysics phenomena of three regenerator configurations, horizontal case and two injection direction of Heat Transfer Fluid (HTF): top and bottom in vertical case. The study is done for the charge and discharge cycles of the solid-solid and solid-liquid phase transitions of PCM. First, the temperature dependence of the thermal and physical properties of paraffin as PCM is characterised. Second, an experimental study of an annular latent storage system was carried out. Also, an experimental mesh method was introduced to compare the energy behaviour of the three cases. Third, a numerical analysis of the experimental storage unit with low thermal diffusion is performed. The experimental results are confronted with the numerical results obtained with ANSYS Fluent and COMSOL Multiphysics commercial software. Last, the three configurations are compared to a reference case without gravitational field. The results show that specific mechanisms control the thermal and energetic behaviour of the regenerator. Furthermore, several parameters, such as storage density, distribution of energy storage rate in the different regenerator components (PCM, HTF, and heat exchanger), were analysed. Altogether, the results supply important information to understand the dynamics of passive storage systems.

The production of electric energy from solar radiation is nowadays one of the most investigated and developed “carbon free” technology. A throughout investigation of the ceramics most commonly used as heat transfer fluids and/or heat storage materials for concentrating solar power systems (i.e. alkaline and heart alkaline nitrate/nitrite mixtures) is here reported. The study stems by the need to base materials selection on an accurate and critical knowledge of all their characteristics, including their thermophysical, environmental compatibility, and economic features. At this purpose, a rating criterion have been established, to readily show the advantages and disadvantages of each material, and to highlight which characteristics of the examined materials need to be further investigated and improved. Nitrate/nitrite mixtures have also been compared with other ceramics used for thermal storage, such as solid fillers, liquid metals, other salt mixtures, or phase change materials.

The vaporization/decomposition of single-phase BaCeO3 samples was studied by the Knudsen Effusion Mass Spectrometry technique in the overall temperature range 1647–1923 K. The partial pressures of the gaseous species BaO(g), CeO2(g) and CeO(g) were monitored as a function of temperature. The formation of reduced form of cerium oxide as a product of the high temperature decomposition of BaCeO3 under the given experimental conditions was suggested by the low value of the measured CeO2(g)/CeO(g) pressure ratio and confirmed by the XRD spectra of the vaporization residues. The equilibrium data were tentatively processed according to various heterogeneous equilibria that may be established in the cell: (i) BaCeO3(s) = BaO(g) + CeO2(s); (ii) BaCeO3(s) + CeO(g) = BaO(g) + Ce2O3(s); (iii) BaCeO3(s) = BaO(g) + CeO2(g). The corresponding enthalpy changes were calculated by the third-law method and the enthalpy of formation of BaCeO3 derived thereafter. The thermodynamic analysis confirms that the decomposition process forming CeO2(s) is very unlikely to occur under the high temperature, high vacuum conditions used in the present study. The analysis of process BaCeO3(s) = BaO(g) + CeO2(g), not involving solid products, was selected as the most reliable and leads to a value for the enthalpy of formation of barium cerate (Δf$$H_{{298}}^{^\circ }$$ (BaCeO3) = –1688.7 ± 6.2 kJ/mol) in agreement with the available calorimetric determinations.

Nanostructured scheelite (CaWO4) was synthesized directly from enriched wolframite (Fe1-xMnxWO4) ore (55.18 % WO3) and lime (CaO) by energetic planetary milling, with no need of high-temperature calcination. After 48 h milling, wolframite was fully converted into nanostructured CaWO4. The mechanochemically derived products, when refluxed overnight in boiling Na2CO3 0.7 M at atmospheric pressure, showed practically complete (> 95 %) dissolution of the calcium tungstate, leaving CaCO3 in the solid residue. In contrast, the very same leaching treatment, when applied to either bare enriched wolframite or pure micro-crystalline CaWO4, did cause a scarse or little solubilization of tungsten. These results confirm the much higher reactivity of nanostructured scheelite in leaching treatments. The observed mechanochemical synthetic route may lead to less energy-intensive and lower environmental impact of tungsten-bearing minerals processing.

Chemical storage systems are a promising innovative route to overcome the issue of the solar irradiation storage, resulting as cost effective and with high energy density. A main problem with these kinds of materials is to design a synthesis method for preparing stable reactive structures, presenting at the same time a high volumetric charging/discharging enthalpy. At this purpose, a size controlled spinel was produced, characterized and investigated regarding its thermophysical and kinetics properties. The obtained powder presents an average diameter between 100 and 200 µm and an energy density of 133 J/g and an experimental test was carried out to verify the spinel morphology stability under thermal cycles. The specific heat is similar to other structured chemical storage system and makes the spinel feasible to be used also as sensible accumulation medium. Despite the relatively high particles size, and the expected small exposed reactive area, the charging, and especially discharging reaction rates resulted particularly favourable and comparable with the reported behaviour of micrometric powders. The particularly simple preparation method plus the cost effectiveness of the precursors leads to a quite convenient expected cost for the storage material, absolutely similar to commercially available accumulation systems.

Reversible solid oxide cells (RSOCs) represent a promising technology for the efficient exploitation of intrinsically intermittent renewable energy sources. RSOCs allow to derive fuel and chemicals from power (power-to-gas technology, P2G) and power from fuel and chemicals (gas-to-power technology, GTP) and can be interchangeably operated either as a solid oxide fuel cell (SOFC) or as a solid oxide electrolyzer cell (SOEC). The key aspect to render these devices competitive on a market scale is the development of multi-tasking, reliable, cost-effective and long-lasting electrodes (1,2). Besides, to overcome the issues related to hydrogen production, storage and distribution (e.g. impractical conversion of the existing grid to hydrogen-based infrastructures), the fuel-electrode of RSOCs should ensure high catalytic activity and coking resistance toward carbon-containing species (3-4). Using a hydrocarbon-tolerant fuel electrode, energy can be obtained by natural gas and biogas (SOFC-mode), with useful recovery of CO2 in the exhausts (carbon capture and storage, CCS). Besides, if the electrode is also active towards CO2 electrolysis (SOEC mode), CO2 is reduced to CO and O2 (carbon capture and utilization, CCU). Ni-YSZ is the reference fuel-electrode material for both H2 fed SOFC and for CO2 electrolysis in SOEC. Nevertheless, Ni-based cermets cannot be used in SOFCs fed with methane-containing fuels, as they suffer from two main drawbacks: mechanical instability upon NiO-Ni redox cycles (5) and passivation due to coking, being Ni a catalyst for methane cracking (3, 4). Moreover, during Ni-YSZ operation in CO2-SOEC mode, ZrO2 reduction can occur at high cathodic potential, resulting in Ni-Zr compounds formation (6). In this work, a recently developed (7, 8) composite material containing La0.6Sr0.4Fe0.8Mn0.2O3-δ (LSFMn) and 5wt% Ni-containing Ce0.58Sm0.15O2-δ (NiSDC) is tested as fuel electrode for LSGM-electrolyte supported cells. In reducing conditions, Fe exsolved from the LSFMn perovskite forms a Fe-Ni alloy with Ni present on SDC. In SOFC mode, the composite is designed to operate in dry methane: Fe-Ni catalytic sites activate CH4, which is successively oxidized on Mn-containing LSFMn, while SDC increases the O2- supply at the anode to get rid of any carbonaceous deposits. As Fe-Ni alloy was reported to be highly active for CO2 reduction (9), the composite was also tested as SOEC cathode in different CO2:CO ratios. LSFMn+NiSDC was tested in SOFC-mode as anode for hydrogen, dry methane and carbon monoxide oxidation and showed power density outputs of 657, 668 and 527 mW/cm2, respectively (Fig. a), a redox stable behavior and coking resistance for over 120 h. LSFMn+NiSDC in SOEC-mode delivered 2.66 A/cm2 at 2 V in 95:5 CO2:CO mixture (Fig. b), keeping 1 A/cm2 of current density output for over 40 h. (1) - M. Mogensen, M. Chen, H. Frandsen, C. Graves, J. Hansen, K. Hansen, A. Hauch, T. Jacobsen, S. Jensen, T. Skafte, Reversible solid-oxide cells for clean and sustainable energy, Clean Energy, 3 (2019) 175-201. (2) - M.B. Mogensen, Materials for Reversible Solid Oxide Cells, Current Opinion in Electrochemistry, (2020). (3) - M. Mogensen, K. Kammer, Conversion of hydrocarbons in solid oxide fuel cells, Annual Review of Materials Research, 33 (2003) 321-331. (4) - S. McIntosh, R.J. Gorte, Direct hydrocarbon solid oxide fuel cells, Chemical reviews, 104 (2004) 4845-4866. (5) - J. Malzbender, R. Steinbrech, Advanced measurement techniques to characterize thermo-mechanical aspects of solid oxide fuel cells, Journal of Power Sources, 173 (2007) 60-67 (6) - A. Hauch, K. Brodersen, M. Chen, M.B. Mogensen, Ni/YSZ electrodes structures optimized for increased electrolysis performance and durability, Solid State Ionics, 293 (2016) 27-36 (7) - L. Duranti, I. Luisetto, S. Licoccia, C. Del Gaudio, E. Di Bartolomeo, Electrochemical performance and stability of LSFMn+ NiSDC anode in dry methane, Electrochimica Acta, (2020) 137116. (8) - L. Duranti, I.N. Sora, F. Zurlo, I. Luisetto, S. Licoccia, E. Di Bartolomeo, The role of manganese substitution on the redox behavior of La0.6Sr0.4Fe0.8Mn0.2O3-δ, Journal of the European Ceramic Society, (2020) ( 9 ) - Liu, S., Liu, Q., & Luo, J. L. (2016). Highly stable and efficient catalyst with in situ exsolved Fe–Ni alloy nanospheres socketed on an oxygen deficient perovskite for direct CO2 electrolysis. ACS Catalysis, 6(9), 6219-6228. Figure 1

Despite its large interesting as component for low melting HTF and HSM, very few thermodynamics information is available regarding calcium nitrate and its mixtures. In this paper the binaries between Ca(NO3)2 and both NaNO3 and KNO3 are experimentally investigate by DSC and Neutron scattering. The results show that the solid phase of the binaries is composed by a solid solution of single nitrates. The DSC pattern and the eutectic point were modeled by the regular solution theory and the fitting parameters are reported. © 2019 Author(s).

With the aim of supporting the thermodynamic modeling of phase equilibria of molten salt mixtures, this article investigates the solid phases present in NaNO3 and KNO3 binary mixtures. To that end, an innovative approach based on the combined use of high-temperature Neutron Scattering Analysis and Differential Scanning Calorimetry was proposed. A solid phase not reported before was detected close to the solidus curve in the central part of the phase diagram, and its diffraction pattern was assigned to a mixed nitrate phase, i.e. a solid solution of the two salts. © 2018 Author(s).

Molten salt (MS) mixtures are used for the transport (HTF-heat transfer fluid) and storage of heat (HSM-heat storage material) in Concentration Solar Plants (CSP). In general, alkaline and earth-alkaline nitrate/nitrite mixtures are employed. Along with its upper stability temperature, the melting point (liquidus point) of a MS mixture is one of the main parameters which defines its usefulness as a HTF and HSM medium. As a result, we would like to develop a predictive model which will allow us to forecast freezing points for different MS mixture compositions; thus circumventing the need to determine experimentally the phase diagram for each MS mixture. To model ternary/quaternary phase diagram, parameters for the binary subsystems are to be determined, which is the purpose of the concerned work. In a binary system with components A and B, in phase equilibrium conditions (e.g. liquid and solid) the chemical potentials (partial molar Gibbs energy) for each component in each phase are equal. For an ideal solution it is possible to calculate the mixing (A+B) Gibbs energy:ΔG = ΔH - TΔS = RT(xAlnxA + xBlnxB) In case of non-ideal solid/liquid mixtures, such as the nitrates/nitrites compositions investigated in this work, the actual value will differ from the ideal one by an amount defined as the "mixing" (mix) Gibbs free energy. If the resulting mixtures is assumed, as indicated in the previous literature, to follow a "regular solution" model, where all the non-ideality is considered included in the enthalpy of mixing value and considering, for instance, the A component: ΔG0=(ΔHA-TΔSA)+(ΔHmixAL-TΔSmixAL)-(ΔHmixAS-TΔSmixAS) where the molar partial amounts can be calculated from the total value by the Gibbs Duhem equation: (ΔHmixAL=ΔHmix-XBLdΔHmixdXBL)L;(ΔHmixAS=ΔHmix-XBSdΔHmixdXBS)S and, in general, it is possible to express the mixing enthalpy for solids and liquids as a function of the mol fraction: ΔHLmix=XALXBL(a1+b1XAL+c1XALXBL),ΔHSmix=XASXBS(a2+b2XAS+c2XASXBS) From the latter expressions it can be possible to modelize the phase diagram of a binary mixtures by using the a,b and c couples of parameters. To calculate those coefficients a method commonly employed in literature is to measure the mixing enthalpies, or to use one reported of the enthalpy of mixing (for instance for the liquid state) and calculate the other one using the phase diagram points. A direct ΔHmix (in solid or liquid phase) measurement can be difficult to carry out using common DSC equipment generally present in research laboratories. In fact, such determinations can be, in principle, performed, but the obtained data will be affected by large experimental errors. On the other hand, it is possible to obtain values with great precision regarding the algebraic sum of mixing enthalpies and the phase diagram trend. For this reason, only the phase diagrams are proposed to be used to calculate a, b, c parameters, and, subsequently, the total (liquid-solid algebraic sum) enthalpy of mixing will be employed to verify their validity. At this aim, a C++ code was assessed and used. Three binary mixtures were considered by combining NaNO3, KNO3 and NaNO2. © 2016 Author(s).

Structure stability and electrical conductivity of La 1-x Sr x Fe 0.8 Cu 0.2 O 3-δ with x = 0.2, 0.4 were investigated both in air and in hydrogen to explore their potential applications as symmetric electrodes for solid oxide fuel cells. La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ (LSGM) electrolyte supported symmetric fuel cells were fabricated and tested in air/hydrogen ambient in 650–800 °C temperature range achieving a maximum power density of 162 mW cm −2 . To improve the cell performance, a composite electrode (70 wt% La 1-x Sr x Fe 0.8 Cu 0.2 O 3-δ −30 wt% Gd 0.2 Ce 0.8 O 3-δ ) was successfully evaluated both at the anode and the cathode sides decreasing the cell polarization resistance to 0.454 Ω cm 2 at 800 °C and reaching a single cell maximum power density of 294 mW cm −2 .

The employment of parabolic trough solar power plants (PT-CSP) for electrical power and process heat generation is one of the most promising technologies for carbon free energy production. The selection of thermal fluids, both for the heat transfer (heat transfer fluid, HTF) and the storage (heat storage material, HSM), is a crucial point for increasing CSP efficiency and cost effectiveness. In this paper two different PT-CSP configurations, both presenting a double tanks storage system, are compared. In particular, two different medium size (50 MWe) plant schemes, presenting two different working fluids as HTF, are described and analysed. In the first scheme a “binary” molten salt mixture, composed of sodium and potassium nitrate, is considered, while, in the second one, the employment, as HTF, of a “ternary” mixture, consisting of sodium potassium and lithium nitrates, is investigated. In both cases, the binary mixture is used for thermal storage (HSM). The first scheme represents the configuration developed by ENEA and already used for the Archimede plant in Priolo Gargallo (Sicily-Italy). The second one is an innovative proposal, which aims to improve CSP plants performances and to reduce operating costs. In particular, since the ternary mixture has a considerably lower freezing temperature than the binary one, this solution allows to keep the system at a lower temperature overnight, so reducing thermal energy losses. In first instance, it is necessary to characterize the binary and ternary mixtures respect to their thermo-physical features. The two CSP configurations are then sized and, by a techno/economic evaluation, compared with respect to the calculated unit cost of electricity production.

Thermochemical water splitting cycles, where the H2O molecule is converted into hydrogen and oxygen by using recyclable and in general inorganic compounds as intermediates, basically consist of two separate sections, where, respectively, hydrogen and oxygen are produced. The most investigated cycles are based on the employment of sulphur containing species; generally, they differs with respect to how hydrogen is produced, but, basically, the step for oxygen formation is invariably a thermo-catalytical solar powered SO3 decomposition. Despite several important studies were dedicated to the development of a solar reactor for this task, the manageability of a solar receiver plant presenting a corrosive acid at high temperature is still a problematic issue. With the main target to reduce the materials cost of the necessary equipment, an intermediate metal oxide is employed; it is reacted with sulphuric acid or ammonium sulphate (according to the cycle considered) to produce the correspondent metal sulphate, which, in turn, is decomposed into sulphur dioxide and oxygen. The present article describes the experimental results obtained for each cycle step, two oxide/sulphate (iron (III) and Zn) systems are used and compared, and, all considered, the couple zinc oxide/sulphate appears to be the most feasible for the process, though, the use of iron (III) sulphate would allow to operate the process at a maximum temperature below 700 °C. A mass and thermal balances analysis for the proposed oxygen production steps were carried out, and results are compared with the reported values where sulphuric acid is directly decomposed, with a final discussion about advantages and drawbacks of both methods. © 2015 Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Barium cerate-based electrolytes containing different amounts of Nb5+ as a dopant were investigated with the aim of attaining materials with improved chemical stability. BaCe0.9-xNbxY0.1O3-x (BCYN) powders with different compositions (0 {less than or equal to} x {less than or equal to} 0.20) were synthesized by citrate-nitrate auto-combustion method and pure single phases were obtained at 1000 {degree sign}C. Dense pellets were obtained using sintering a temperature of 1450 {degree sign}C for 10 hours. The chemical stability was evaluated by XRD analysis after CO2 exposure at 700{degree sign}C for 3 hours. To investigate the effect of Nb5+ doping on conductivity, electrochemical impedance spectroscopy (EIS) measurements were carried out in the 400-700 {degree sign}C temperature range in different atmospheres.

Ta2O5 nanopowders to be used as sensing electrodes in high temperature electrochemical gas sensors for hydrocarbons detection were synthesized using a sol-gel method and their structural and microstructural properties were investigated. The as-synthesized powders were heated at different temperatures in the range 250-1000 degrees C and characterized by TG-DTA, XRD, SEM, TEM and FT-IR. This investigation allowed to identify the correct thermal treatments to achieve the microstructural, textural and functional stability of materials working at high temperature, preserving their nano-metric grain size. Planar sensors fabricated by using Ta2O5 powders treated at 750 degrees C showed promising results for the selective detection of propylene at high temperature (700 degrees C). The good stability of the sensing response after gas exposure at high temperature was correlated to the stable microstructure the electrodes. Thus, Ta2O5 powders seems good candidate as sensing electrode for sensors for automotive exhausts monitoring.

The development of proton exchange membranes as electrolytes for polymer electrolyte fuel cells operating at intermediate temperatures has been achieved combining two approaches: the preparation of a cross-linked polymer and the formation of covalent organic/inorganic hybrids. A covalently crosslinked sulfonated polyetheretherketone with elevated degree of sulfonation (DS ) 0.8) was prepared by reaction with HSO3Cl (SOPEEK). No degradation of PEEK was detected upon sulfonation, but only cross-linking via sulfonic groups with formation of SO2 moieties was observed. The extent of ramification was calculated by analyzing the 1 H nuclear magnetic resonance (NMR) spectra of the products and resulted in 20% of the total amount of -SO3H groups present in the polymer. The solubility of the -SO2Cl precursor in organic solvents allowed easy carrying out of functionalization reactions in homogeneous conditions by lithiation and subsequent reaction with SiCl 4, thus introducing covalenly linked silicon moieties (SOSiPEEK) at the ratios 1:0.25 and 1:0.50 per monomeric unit. The products were characterized by 1 H and 13 C NMR, attenuated total reflectance Fourier transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry.

Sulfonated poly ether ether ketone (SPEEK) with a high degree of sulfonation (DS = 0.9) was mixed with a modified silane bearing a sulfonic acid function (sulfonated diphenylsilanediole, SDPDO).Homogeneous composite membranes with several SPEEK:SDPDO ratios, were obtained. The addition of the ormosil significantly improved the water uptake and solubility properties of pure SPEEK.The structural and electrochemical characteristics of the composite membranes were investigated by means of thermogravimetric analysis (TG), field emission scanning electron microscopy (FE-SEM), and electrochemical impedance spectroscopy (EIS). The conductivity values of the composites SPEEK/SDPDO demonstrated that they possess good proton transport characteristics, thus being suitable for application in Polymer Electrolyte Fuel Cells operating at intermediate temperature.

Diphenylsilanediol (DPDO) reacts with triethoxysilane (TREOS) in anhydrous conditions and in the presence of pyridine, to form complex mixtures of linear and cyclic condensation products which were identified by 29Si NMR and ATR/FTIR spectroscopies. The distribution of products can be varied by modifying the reaction conditions. Spectroscopic analysis allowed to identify the optimal reagents ratio and concentration for the production of hetero-condensation products minimizing the number of residual –OH groups whose presence would affect the performance of optical waveguides based on the synthesised nano building blocks.

Four chloroiron meso -triphenyl-substituted corrolates have been synthesized and studied by 1 H NMR spectroscopy. As in the case of the β-pyrrole-octaalkylcorrolatoiron chloride complexes studied previously [Inorg. Chem. 39 (2000) 3466], these complexes were also found to be S=3/2 Fe(III) corrolate( 2− ) π-cation radical species, where the macrocycle radical electron is antiferromagnetically coupled to the metal electrons to give an overall S=1 complex. This conclusion is based upon the large alternating-sign contact shifts observed for the meso -phenyl protons. The 1 H isotropic shifts of the pyrrole-H of these chloroiron–triphenylcorrolate complexes are similar to those of the chloroiron tri-(pentafluorophenyl)corrolate complex reported previously and said to be a S=1 Fe(IV) complex bound to a simple corrolate( 3− ) ligand [Inorg. Chem. 39 (2000) 2704]. The 19 F NMR spectrum of the latter complex shows that it has small (negative) phenyl-F isotropic shifts for all phenyl-F, which might suggest that this single compound has a different electronic structure than all other chloroiron corrolates investigated thus far. However, there have as yet been very few NMR investigations of paramagnetic metal macrocycles having fluorine substituents, and thus it is premature to conclude that the small phenyl-F isotropic shifts are definitive proof of small spin density at the meso positions of the corrolate ring. It is concluded that pyrrole-H chemical shifts alone cannot differentiate the two possible electron configurations, simple S=1 Fe(IV) (Corr 3− ) and antiferromagnetically coupled S=3/2 Fe(III) (Corr 2− ), and that based on the 1 H investigations reported in this and two previous papers, all chloroiron corrolates reported thus far, with the exception of one, have the electron configuration S=3/2 Fe(III) (Corr 2− ), in which the corrolate unpaired electron is antiferromagnetically coupled to the three metal electrons, yielding an overall spin for the complex, S=1. The electron configuration of the one exception, the strongly electron-withdrawing tri-(pentafluorophenyl)corrolate complex of iron chloride, cannot as yet be definitively assigned.

A general, efficient and experimentally simple method for the synthesis of covalently crosslinked class II hybrid polymers based on PolyEtherEtherKetone (PEEK) with a high degree of sulfonation (DS = 0.8) was performed. The synthetic strategy foreseen two steps: the first one, direct sulfonation, led to the introduction of sulfonic acid groups and to the formation of sulfone bridges among repeat units. The second step, lithiation and silylation, led to the formation of covalent bonds between the organic backbone and Si(OH)3 moieties. The materials were characterized by 1H NMR Spectroscopy, ATR/FTIR Spectroscopy, Thermogravimetric Analysis (TGA) and Mass Spectrometry. Preliminary proton conduction measurements in dry conditions were performed. The introduction of silicon groups in the system improved thermal stability.