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Ni–P and Ni–P–Re coatings with various concentrations of P and Re were obtained on copper substrate by the electroless deposition from succinate baths. The influence of certain bath parameters on the alloys composition and the deposition rate is presented, followed by the relation between these process parameters as well as the rhenium addition on the surface morphology, microstructure, phase composition and thermal stability of the deposited films. The conditions for the formation of uniform, smooth and compact alloy films on copper substrate were defined. On the basis of X-ray diffraction analysis it can be stated that the alloy containing less than 5.5 wt.% of phosphorus exhibits fully crystalline microstructure for both studied cases: Ni–P and Ni–P–Re alloys. Differential scanning calorimetry analysis performed for the Ni-based alloy layers with and without rhenium additive and the same level of phosphorus are provided, proving, that the addition of rhenium to the Ni–P coatings results in the increase of the crystallization temperature. The increase of the crystallization temperature from 411 °C to 434 °C was noted for NiP5.0 alloy, where the addition of Re was only of 3.7 wt.%.

The lanthanum strontium cobalt ferrite (LSCF)-Ag composite cathode material was prepared in aqueous solution by new one-step method. In this method silver nanoparticles obtained by the reduction of [Ag(NH3)2]+ complex with sucrose were directly deposited onto the surface of LSCF powder. UV–Vis spectra of supernatant solution taken during synthesis showed the presence of a sharp excitation band near 397 nm attributed to the surface plasmon excitation of silver nanoparticles. Obtained composite powder was sintered to samaria doped ceria electrolyte in one step sintering procedure at 1000 °C. The presence of silver in LSCF cathode facilitates the oxygen reduction. The comparison of impedance spectra of LSCF-Ag cathodes with spectra reported in literature for similar LSCF cathodes shows that this effect is important at lower oxygen partial pressures. The analysis of the electrochemical impedance spectra recorded in the range 10−2–1010 Hz reveals that the second high frequency semicircle ascribed to the electrolyte grain boundary impedance is distorted due to process belonging to oxygen reduction reaction.

A proton-conducting membrane involving modified barium cerate BaCe0.9Y0.1O3 was obtained in the form of gas-tight ceramic tape. Monophase Ca0.05Ba0.95Ce0.9Y0.1O3 (5CBCY) powder and an organic medium consisting of polyvinyl butyral used as a binder, a plasticiser based on carboxylic acid esters, and a mixture of ethanol and methyl ethyl ketone were used to prepare slurry for the tape-casting process. Gas-tight ceramic tapes involving 5CBCY and sintered samples were tested as electrolytes in hydrogen–oxygen button solid oxide fuel cells within the temperature range 500–750 °C. Variations in OCV and ohmic resistance (Rs) were determined within this range. A considerable decrease in Rs value was recorded for 5CBCY tape compared to 5CBCY sintered samples. A series of symmetrical cells with 5CBCY electrolytes was analysed. The lowest ASR values for the investigated cells were found for a newly elaborated LSCF–5CBCY cathode as well as for a Ni–5CBCY anode. These electrode materials appear to be suitable for 5CBCY-electrolyte-supported solid oxide fuel cells.

Results on D. desulfuricans biofilm formation on austenitic-ferritic duplex (2205 DSS) and superaustenitic (904L) stainless steels are presented. Surface characterization including the structure, configuration and chemical composition of biofilms were carried out using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Electrochemical impedance spectroscopy (EIS) measurements were used to monitor the attachment activity of bacteria on the steels' surface and to determine the effect of bacteria on passivity. It was proved that investigated steels are rapidly colonized by bacteria. The presence of biofilm caused significant ennoblement of 904L steel surface, while retarded the attainment of high passive state of 2205 DSS. XPS analysis revealed significant sulphidation of the biofilm and its layered structure. Accumulation of sulphides and hydroxides was proved in the outermost layer, while the increasing contents of disulphides, organometallic and C N bonds were detected in the internal part of the biofilm. Irreversible bondings between steel matrix and biofilm had also been observed.

Silver is one of the most promising cathode materials for low temperature (300–500 °C) solid oxide fuel cells. The most important disadvantage of silver is its migration in the electric field. For better understanding of this phenomenon, an in situ observation of the migration mechanism was undertaken with the use of high-temperature microscopes. Scandia stabilised ceria doped zirconia CeScSZ electrolyte prepared from commercial powder was examined before and after silver migration experiments using scanning electron microscope. X-ray diffraction, broadband electrochemical impedance spectroscopy, and X-ray photoelectron spectroscopy. The silver electrodes for solid oxide fuel cells were prepared using magnetron sputtering. The described cells under polarisation were examined using a high-temperature low energy electron microscope. Reference cells and post-mortem cells were observed using a scanning electron microscope equipped with high temperature stage. Under polarisation, silver moved inside the electrolyte and along the surface towards the region between electrodes. The structures thus formed were similar to those previously described in the literature; however, direct observation of the deposit growth was unsuccessful. In situ scanning electron microscopy observations of the silver electrode at 650 °C revealed neither melting of the smallest silver particles nor movement of silver structures. Silver migration through the electrolyte caused a reduction in grain interior conductivity of the electrolyte, whereas its grain boundary conductivity remained unaffected.

Composite cathodes contain Ba0.5Sr0.5Co0.8Fe0.2O3–δ and La0.6Sr0.4Co0.8Fe0.2O3–δ were tested in different configuration for achieving cathode of area specific resistance lower than Ba0.5Sr0.5Co0.8Fe0.2O3–δ and La0.6Sr0.4Co0.8Fe0.2O3–δ cathodes. Electrodes were screen printed on samaria-doped ceria electrolyte half-discs and tested in the three electrode setup by the electrochemical impedance spectroscopy. Microstructure was observed by scanning electron microscopy. The lowest area specific resistance 0.46 and 2.77 Ω cm−2 at 700 °C and 600 °C respectively revealed composite cathode contain Ba0.5Sr0.5Co0.8Fe0.2O3–δ and La0.6Sr0.4Co0.8Fe0.2O3–δ in 1:1 weight ratio. The area specific resistance of this cathode is characterized by the lowest activation energy among tested cathodes.

Results on biofilm formation and microbiologically influenced corrosion induced by pure D. desulfuricans strain on 2205 duplex stainless steel (DSS) are presented. Biofilm development stimulated by DSM642 standard strain was evaluated with reference to their metabolic activity and to the surface characterization including the structure and configuration of the biofilm. Electrochemical techniques (open circuit potential, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves) and X-ray photoelectron spectroscopy (XPS) were carried out to determine the effect of bacteria on the passivity and corrosion resistance of 2205 DSS. The electrochemical results showed that the DSS corrosion resistance was affected in the presence of DSM642 biofilm. This statement was based on the significant decrease in the charge transfer resistance (R1) obtained from EIS and the increase in the measured current densities obtained from potentiodynamic polarization curves. Although the breakdown potentials (Eb) were still high, SEM observations revealed micropits as well as signs of crevice attack on the steel surface. Significant sulphidation of the passive film affected the nature of cathodic behaviour of steel and helped to impede micropit growth. XPS analysis revealed the layered structure of the biofilm. Accumulation of sulphides and hydroxides was proved in the outermost layer, while the increasing contents of disulphides, organometallic and C N bonds were detected along the biofilm thickness in the XPS analysis.

The gelcasting method was used to form gastight Ba0.95Ca0.05Ce0.9Y0.1O3 samples proposed for use as proton-conducting electrolytes in solid oxide fuel cells. Methylcellulose was used as an environmentally friendly shaping agent for Ba0.95Ca0.05Ce0.9Y0.1O3 powder in an ethanol solution. Samples of Ba0.95Ca0.05Ce0.9Y0.1O3 were also prepared from the same powder via traditional isostatic pressing, as a reference for cast samples, and sintered in the same conditions. Comparative studies of the physicochemical properties of Ba0.95Ca0.05Ce0.9Y0.1O3 electrolytes, formed by means of these two methods and then sintered at 1550 °C for 2.5 h, were presented and discussed. Using the X-ray diffraction method, only the pure orthorhombic phase of BaCe0.9Y0.1O3 was detected in the Ba0.95Ca0.05Ce0.9Y0.1O3 powder, as well as in the Ba0.95Ca0.05Ce0.9Y0.1O3 sintered pellets formed via both gelcasting (A) and isostatic pressing (B). Thermal effects occurring during heating of methylcellulose, as well as ceramic Ba0.95Ca0.05Ce0.9Y0.1O3 powder, dried cast samples obtained from the prepared slurry, and sintered Ba0.95Ca0.05Ce0.9Y0.1O3 samples, were examined by differential scanning calorimetry, differential thermal analysis, thermogravimetric analysis, and evolved gas analysis of volatile products using a quadrupole mass spectrometer. The measurements were performed within the temperature range of 20–1200 °C in air. Based on dilatometric tests, it was found that the Ba0.95Ca0.05Ce0.9Y0.1O3 cast samples exhibited slightly higher degree of sinterability than the 5CBCY samples obtained by isostatic pressing. In comparison with pressed pellets, higher values of total electrical conductivity in air or in a gas mixture of 5% H2 in Ar were also attained for Ba0.95Ca0.05Ce0.9Y0.1O3 cast samples. The Ba0.95Ca0.05Ce0.9Y0.1O3 samples were used to construct oxygen–hydrogen electrolytes for solid oxide fuel cells. The results of the electrochemical performance of solid oxide fuel cells with Ba0.95Ca0.05Ce0.9Y0.1O3 electrolytes were comparable to the data in the literature on BaCe0.9Y0.1O3 electrolytes. An electrochemical study of a Ba0.5Sr0.5Co0.8Fe0.2O3−δ|Ba0.95Ca0.05Ce0.9Y0.1O3 interface was also performed. Ba0.5Sr0.5Co0.8Fe0.2O3−δ appears to be a suitable cathode material for a Ba0.95Ca0.05Ce0.9Y0.1O3 electrolyte.

The Sm0.5Sr0.5CoO3–δ–La0.6Sr0.4FeO3–δ 1:1 composite, obtained by sintering mixture of components, was tested as a prospective cathode material for the oxygen reduction reaction in solid oxide fuel cells. Catalytic activity of the prepared material was characterized using electrochemical impedance spectroscopy at 400, 450, 500, 550, 600, 650, and 700 °C in oxygen and oxygen-argon mixtures in half-cells with Sm0.2Ce0.8O1.9 as the electrolyte. Relatively low activation energies (65.2, 66.9, and 56.3 kJ mol−1 for PO2/P = 1.0, 0.1, and 0.01, respectively) for the reaction polarization resistance were observed. The specific surface area and the pore distribution were measured by N2 adsorption method. The non-localized density functional theory was used in the analysis of the porosity data. The activity of the prepared composite depended on the pore structure which, in turns, depends on the sintering temperature. The best results were obtained for the composite sintered at the temperature of 1000 °C, where significant decrease in porosity is observed. The series of 53 thermal cycles, consisting of heating to 750 °C and cooling to room temperature confirmed the stability of the composite.

The behavior of a silver electrode contacting Ce0.8Sm0.2O1.9 (samaria-doped ceria or SDC) electrolyte under external cathodic polarization in the temperature range 350–700 °C was examined by means of long-term polarization experiments, scanning electron microscopy, and electrochemical impedance spectroscopy. A silver deposit is formed around the silver cathode via a surface migration mechanism without the occurrence of the gas-phase transport phenomenon during polarization. This results in an increase in both the electrode-electrolyte contact area and the triple-phase boundary length, which in turn causes decreases in charge transfer resistance and electrolyte resistance.

Composite cathodes Ag-La0.6Sr0.4Co0.2Fe0.8O3-δ were obtained by two different procedures. In the first procedure porous La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) matrix was prepared by sintering the LSCF paste, the matrix was then saturated with AgNO3 solution and sintered again. Introduced silver crystalized in the form of 10 nm crystallites in the whole LSCF matrix. In the second procedure the paste of silver powder was deposited on the surface of electrolyte and dried. The layer of silver paste was then covered by a layer of the LSCF paste and sintered at 850°C. The following cells were tested: H2|Ni-Ce0.8Gd0.2O1.9|Ce0.8Sm0.2O1.9 LSCF|O2, H2|Ni-Ce0.8Gd0.2O1.9|Ce0.8Sm0.2O1.9|LSCF-Ag|O2 and H2|Ni-Ce0.8Gd0.2O1.9|Ce0.8Sm-O1.9|Ag|LSCF|O2. Introduction of silver interlayer between cathode and electrolyte increased output power by 18-28% whereas introduction of metallic silver into porous LSCF caused increase in power by 14-18%.

Composite cathodes for solid oxide fuel cells composed of metallic silver dispersed in ceramic (La0:8Sr0:2MnO3-σ) matrix were prepared on the surface of solid electrolyte by two-step procedure. First the matrix of controlled porosity was created by sintering mixture of La0:8Sr0:2MnO3-σ powder with the organic polymer beads then the matrix was saturated with AgNO3 solution and sintered again. Such obtained cathodes showed higher electrical conductivity and lower charge transfer resistance in oxygen reduction reaction in comparison to pure ceramic cathodes

Singly-doped and co-doped ceria powders with the formula Ce0.8M0.2O1.9 or Ce0.8M0.15Y0.05O1.9, M = Gd, Sm were synthesized using the spray pyrolysis method at 700 °C. X-ray diffraction analysis showed that all obtained powders were pure cubic CeO2-based solid solutions. Scanning and transmission electron microscopy were used to characterize the morphology of CeO2-based powders. It was found that the prepared powders were composed of fully spherical particles ranging in size from ∼0.1 to 1.3 μm. Additional heat treatment of these powders in the temperature range of 700–1000 °C resulted only in small increased particle size. The particles lost their spherical shape at temperatures above 1200 °C. A study of sintering activity of powders prepared in this way was also performed, using the dilatometric method. Finally, CeO2-based samples were sintered at 1500 °C in air for 2 h. The ionic conductivity of Ce0.8M0.2O1.9 and Ce0.8M0.15Y0.05O1.9 M = Gd, Sm sintered samples were studied by AC impedance spectroscopy. It was found that the partial substitution of Y3+ for Gd3+ resulted in increased ionic conductivity of Ce0.8M0.15Y0.05O1.9, M = Gd, Sm compared to Ce0.8M0.2O1.9, M = Gd, Sm. The possibility of using spherical CeO2-based powders for the preparation of screen-printable paste (to be used in turn for the deposition of gas-tight electrolyte films for anode-supported solid oxide fuel cells) was also investigated. The performance of single anode supported solid oxide fuel cells, involving singly doped ceria as Ce0.8Sm0.2O1.9 or Ce0.8Sm0.15Y0.05O1.9 as oxide electrolytes fueled with gaseous hydrogen, was presented and analyzed. The authors also pointed out that the co-doped ceria electrolytes Ce0.8Sm0.15Y0.05O1.9, M = Gd, Sm seem to be also promising oxide electrolytes for construction solid oxide fuel cells, which utilized solid carbon as fuel.

The direct carbon fuel cells with solid oxide electrolyte (DC-SOFC) and anodes deposited by inject printing (EM/DCIJP) were studied. The cells were fed with carbon fuel obtained by the direct RF plasma splitting of methane. Since the (EM/DCIJP)M/DCIJP technology allows easy modification of electrode material, the effect of Cu addition to the Ni–YSZ anode was investigated. The significant improvement of the cell performance with the new anode was observed.

Influence of the short time external polarization of silver electrode contacted Ce0.8Sm0.2O1.9 electrolyte was studied. Silver is moving along the Ce0.8Sm0.2O1.9 surface during the -0.5 V cathodic polarization at 600°C. It caused both the increase of the electrode - electrolyte contact area and the triple phase boundary length but also decrease of electrolyte and polarization resistances. Deposit of silver oxide was found at the place where the electrode polarized at the potential of 0.5 V contacted the electrolyte and around. The decrease of electrolyte and polarization resistance was smaller but more stable in this case. Composite cathodes were obtained on Ce0.8Sm0.2O1.9 electrolyte with the double step sintering procedure. Silver introduced into a La0.6Sr0.4Co0.8Fe0.2O3 cathode improved a performance of a La0.6Sr0:4Co0.8Fe0.2O3|Ce0.8Sm0.2O1.9|Ni cell by 33%.

The Pechinni method (A) as well as hydrothermal treatment (B) of co-precipitated CeO2-based gels with NaOH solution were used to synthesise pure CeO2, and CeO2-based solid solutions with formula Ce1−xMxO2, Ce1−x(M0.5Ca0.5)xO2 M = Gd, Sm for 0.15

The processes occurring at NiO and CoO monocrystalline electrodes in a basic Li+Na carbonate melt have been investigated at 923 K by electrochemical impedance spectroscopy (EIS). Four various equivalent circuits (two for the NiO electrode and two for the CoO electrode) were employed to examine the data obtained. These equivalent circuits consist of elements that represent the reduction–oxidation of oxygen entities dissolved in the melt, incorporation–extraction of Li + ions into/from the crystallographic network of either Ni or Co oxides and semicondutance properties of electrode materials. The effect of time elapsing since the electrode immersion on the behaviours of these elements was analysed to verify a reliability of the applied models.

Silver-Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) cathodes were prepared in two ways. In the first method, Ag-BSCF composite powder was prepared in ethanol solution, where Ag nanoparticles serving as a component in the preparation of Ag-BSCF composite cathodes had been previously obtained via one-step synthesis in absolute ethanol using a neutral polymer (polyvinylpyrrolidone). To the best of our knowledge, this is the first study to use a Ag sol obtained by the above method for preparation of Ag-BSCF composite powder. Then, a paste containing this powder was screen-printed on a Sm0.2Ce0.8O1.9 electrolyte and sintered at 1,000 °C. In the second technique, an aqueous solution of AgNO3 was added to a previously sintered BSCF cathode, which was then sintered again at 800 °C. The oxygen reduction reaction at the quasi-point BSCF cathode on the Sm0.2Ce0.8O1.9 electrolyte was tested by electrochemical impedance spectroscopy at different oxygen concentrations in three electrode setup. The continuous decrease of polarization resistance was observed under polarization −0.5 V at 600 °C. The comparative studies of both obtained composite Ag-BSCF materials were performed in hydrogen-oxygen IT-SOFC involving samaria-doped ceria as an electrolyte and Ni-Gd0.2Ce0.8O1.9 anode. In both cases, the addition of silver to the cathode caused an increase in current and power density compared with an IT-SOFC built with the same components but involving a monophase BSFC cathode material.