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Abstract: Ba0.5Sr0.5Co0.8Fe0.2O3−δ –xSm0.5Sr0.5CoO3−δ (BSCF–xSSC, x =0–40wt%) composite cathodes supported on Sm0.2Ce0.8O1.9 (SDC) electrolyte were studied for applications in IT-SOFCs. X-ray diffraction patterns showed obvious solid-state reactions between BSCF and SSC. However, the composite materials exhibited higher conductivity than that of pure BSCF, e.g., around 176Scm−1 at 500°C for the x =30wt% composite, which was nearly seven times higher than that of BSCF. The thermal expansion coefficients of the BSCF–SSC were between (18.0 and 21.9)×10−6 K−1 from 30 to 800°C, which was slightly higher than that of BSCF. In addition, electrochemical impedance spectra exhibited the better performance of BSCF–SSC composite cathodes than pure BSCF. The results of the polarization resistance indicated that the optimum content of SSC in the composite cathodes was about 30wt%, e.g., the polarization resistance value of BSCF–30wt%SSC was only 0.71Ωcm2 at 550°C, about one seventh of that BSCF at 550°C. [Copyright &y& Elsevier]

Abstract: In order to increase the three phase boundary (TPB) length through lowering the NiO particles to submicro-size, NiO powder was synthesized by the precipitation method and the corresponding NiO-YSZ (8mol% yttria-stabilized zirconia) composite anodes were investigated in this paper. The crystallite size of the as-synthesized NiO particle was 20–30nm. The particles were agglomerated, but the agglomerates could be partially broken by grinding. The powder has an average particle size of 0.36μm after grinding. NiO-YSZ anodes were fabricated by mixing the as-prepared NiO with commercial YSZ powders together. In order to form suitable porosity, flour was used as the pore-former, which played a key role in affecting the anode performance. Characteristics of the anodes, namely, shrinkage behavior, temperature-programmed reduction (TPR) measurement at a constant temperature (i.e., a modified TPR technique) and resistance characteristic during reduction were investigated. The maximum power density of the anode-supported YSZ film single cell was 905mW/cm2 at 750°C based on the Anode-30 (NiO, YSZ and flour was mixed in the weight ratio of 5:5:3). As a summary, high cell performance could be achieved at reduced temperature with the as-fabricated NiO-YSZ anode containing a suitable microstructure. [Copyright &y& Elsevier]

Abstract: The mixed conductor GdBaCo2O5+δ (GBCO) was studied as a promising cathode candidate for IT-SOFCs. It exhibited good chemical compatibility with Sm0.2Ce0.8O1.9 (samaria-doped ceria, SDC) electrolyte as proved by XRD results. Its conductivity was about 512–290Scm−1 in the temperature range 500–800°C. The thermal expansion coefficient (TEC) was about 20.1×10−6 K−1 between 30°C and 900°C in air, which was similar to other cobaltite perovskite cathodes. The sintering temperature had a strong effect on the electrochemical properties of GBCO. DC polarization and ac impedance spectroscopy results confirmed that 1050°C was the optimum sintering temperature. Polarization resistance values for the GBCO cathode on SDC electrolyte were 0.15Ωcm2 at 750°C and 1.11Ωcm2 at 600°C, respectively. [Copyright &y& Elsevier]

Abstract: Composite materials Ba0.5Sr0.5Co0.6Fe0.4O3−δ (BSCF4)–Ce0.8Sm0.2O1.9 (SDC) (BSCF4–SDC) were prepared and characterized as cathode for intermediate temperature SOFC (IT-SOFC). The powder X-ray diffraction (XRD), thermal expansion coefficient (TEC), electrical conductivity and electrochemical property measurement were employed to study the materials. The XRD result proved the reaction between BSCF4 and SDC in BSCF4–SDC. The conductivity of BSCF4–SDC was higher than that of BSCF4; in additions the thermal expansion coefficient of the BSCF4–SDC was about 18% lower than BSCF4 from 30 to 800°C in air. Polarization curves and impedance spectra measured at intermediate temperatures showed the BSCF4–SDC electrode yielded lower resistance values than that of BSCF4 electrode. And the addition of 30wt% SDC to BSCF4 had the best electrochemical properties; e.g., polarization resistance of BSCF4–SDC30 was 0.298Ωcm2 at 550°C, which was nearly 85% lower than that of BSCF electrode. [Copyright &y& Elsevier]

Abstract: In this study, nano-scale rare-earth co-doped Ce0.8Sm0.1Y0.1O1.9 material was prepared by the sol–gel method. When sintered after 1300, 1400, 1500 and 1600°C, the samples all presented well single phase. The SEM result exhibited that when sintered after 1300 and 1400°C, the pellets were denser with fewer pores than those sintered after 1500 and 1600°C; and the sample was over-sintered after sintered over 1500°C. Impedance spectroscopy analyses of the samples sintered at various temperatures were performed at 300–850°C. And electrical conductivity and activation energy of bulk, grain boundary and the whole electrolyte were calculated. The results displayed that, for all samples treated at different temperatures, the activity energies of grain-boundary conduction all presented higher values (1.02–1.20eV) than those of the bulk (0.78–0.85eV); and the samples sintered at 1300 and 1400°C showed much higher total conductivity and lower activation energy than those sintered at 1500 and 1600°C. It demonstrated that rare-earth co-doped Ce0.8Sm0.1Y0.1O1.9 material prepared by the sol–gel method could be easy to sinter at lower temperature dense ceramic electrolyte with better electrical property. [Copyright &y& Elsevier]

Abstract: A glass system based on SiO2–B2O3–Al2O3–BaCO3–PbO2–ZnO was prepared and a sort of compounding was optimized to determine the composition with best performance named AF8. The technical thermal expansion coefficient (t-TEC) is 10.58×10−6 K−1 between 323 and 773K. The resistivity of AF8 is 1.95×104 Ωcm at 800°C. The optimum sealing temperature range was 850–880°C. AF8 glass sealant could adhere with electrolyte of yttria stabilized zirconia (YSZ) well and there were no perforative pores in the sealant. The leak rate of AF8 glass was 0.81×10−7 mbarls−1 cm−1 at 800°C tested by oxygen coulometric titration which was closed to the required value. Around the sealing temperature, contact angle of AF8 on YSZ is about 110°. This angle can make them adhere well under a suitable pressure, and also avoids glass spreading freely on surface of the electrolyte. All measured results approved that AF8 may become a practical sealant for SOFCs. [Copyright &y& Elsevier]

Abstract: Co-doped ceria electrolytes of Ce0.8La0.2−x Y x O1.9 (x =0.02, 0.06, 0.10, 0.14, 0.20) fine powders were prepared with the sol–gel method. The results of X-ray diffraction and Raman spectroscopy showed that all powders crystallite calcined at 800°C were single phase with cubic fluorite structure, the average crystallite sizes calculated by the Scherrer formula were between 27 and 34nm, which was in good agreement with the results of TEM and particle size distribution measurements. The thermal expansion curves of were measured and the thermal expansion coefficients (TEC) between 100 and 800°C were calculated. For the samples of Ce0.8La0.2−x Y x O1.9, in the temperature range of 700–850°C, when x =0.06, 0.10 and 0.14, much higher ionic conductivity was observed than those of the singly doped ceria with same dopant concentration (20% trivalent rare earth) and when x =0.06, maximal conductivity is obtained. It suggested that co-doping with appropriate ratio of lanthanum and yttrium can further improve the electrical performance of ceria-based electrolytes, and these co-doped samples may be the better electrolytes for intermediate-temperature solid oxide fuel cells. [Copyright &y& Elsevier]

Abstract: Perovskite oxides LaTi1−x Li x O3 (x =0.2, 1/3) were synthesized using high-pressure and high-temperature method. This new synthesis route has some advantages. XRD analysis showed that the x =0.2 sample belongs to cubic perovskite-type structure and the x =1/3 sample belongs to orthorhombic perovskite-type structure. EPR measurement indicated that Ti ions were in mixed valence of +3 and +4. IR measurement indicated that the vibration frequency and width of BO6 octahedron stretching vibration absorption band decreases with the increasing of x. Valence of Ti ions can be altered by high-pressure and high-temperature. [Copyright &y& Elsevier]

Abstract: Weakly agglomerated nanocrystalline NiO was synthesized by a homogeneous precipitation method in the presence of urea as the precipitation agent. The reaction mechanism about the hydrolyzation of urea, the precipitate process of the as-synthesized precursor, and the decomposition of the precursor during heating treatment was discussed. The effects of the ions concentration and the calcinations temperature on the powder properties were investigated. The as-synthesized precursor was characterized as hydrated basic carbonate by IR spectrum and TG analysis. The results revealed that crystallization started at about 350°C, and the nanoparticles with the average crystallite size of 5nm were obtained. With increasing the molar ratio of urea to Ni2+ ion, the crystalline size showed a slight increase, and then decrease, however the pH and the yield indicated a pronounced increase. During heating, an enhanced crystallite growth was observed. [Copyright &y& Elsevier]

Abstract: (Ba0.5Sr0.5)1− x Sm x Co0.8Fe0.2O3− δ (BSSCF; x =0.05–0.15) compounds were synthesized with EDTA-Pechini method and characterized by powder X-ray diffraction (XRD), electrical conductivity and thermal expansion coefficient (TEC) measurements, as well as the electrochemical impedance spectra measurement. According to the XRD results, the main phase of the material belongs to the cubic perovskite-type, and the lattice contracting with the increasing contents of Sm3+. The TEC of the compounds is 19.1–20.3×10−6 K−1 from 30 to 800°C, which close to the values of Co-based materials, such as Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF). And the conductivity of BSSCF is higher than that of BSCF; e.g., about 212% higher at 500°C for the x =0.15 compound. Electrochemical impedance spectra at intermediate temperature revealed the better electrochemical performance of BSSCF than BSCF; e.g., the total resistance values of BSSCF electrode is 2.98Ωcm2 at 500°C, nearly 50% lower than that of BSCF. [Copyright &y& Elsevier]

Abstract: Nanocrystalline yttria-stabilized zirconia (YSZ) was synthesized by a homogeneous precipitation process using urea as the precipitation agent. The effects of powders calcinations temperature on the phase evolution, crystalline sizes and electrical properties were investigated. Characterizations revealed that crystallization started at about 773K. Finely dispersed and weakly agglomerated nanocrystalline YSZ with the average crystalline size of 7nm was obtained. During heating, a better crystallization and enhanced crystallite growth was observed. Sintering curves revealed that a densification process appeared in the temperature range of 773–1573K with a well-defined maximum of shrinkage rate at around 1411K. Raman scattering results at room temperature suggested that the major phase was cubic, and the minor one was tetragonal. On reducing the calcinations temperature of powders, the sintered ceramic density increased, corresponding to an increase in the pre-exponential factor and the conductivity. [Copyright &y& Elsevier]

Abstract: Ceria-rare earth solid solutions are known as solid electrolytes with potential applications in solid oxide fuel cell (SOFC). Trivalent rare earth ions enter into solid solution introducing anion vacancies for charge compensation. These oxygen vacancies are quite mobile at moderate temperatures giving rise to a comparatively high ionic conduction. In this study, rare-earth co-doped Ce0.8Sm0.2−x Y x O1.9 (x =0.0–0.20) fine powders were prepared by a sol–gel method. The XRD results showed that all powders crystallite calcined at 800°C were single phase with cubic fluorite structure; the average crystallite size was between 24 and 35nm, which was in good agreement with the results of TEM and particle size distribution measurements. The SEM results exhibited that electrolyte pellets sintered at 1400°C were dense, and the relative densities of these pellets were over 99%. Impedance spectra analysis of these electrolytes has been performed at 250–850°C. The results displayed that Ce0.8Sm0.15Y0.05O1.9 and Ce0.8Sm0.1Y0.1O1.9 appeared higher conductivity and lower activation energy than the singly doped ceria with the same dopant concentration (20% trivalent rare earth) at the temperature range of 550–700°C. The maximum power density and the maximum current density for the single SOFC based on the two samples were higher than singly doped sample with the same vacancy concentration. Therefore, it is concluded that co-doping with an appropriate ratio of samarium and yttrium can further improve the electrical performance of ceria-based electrolytes. [Copyright &y& Elsevier]

Abstract: An electrophoretic deposition (EPD) method was applied for the preparation of yttria-stabilized zirconia (YSZ) thin film on a NiO–YSZ porous anode substrate for solid oxide fuel cell (SOFC) applications. Dense YSZ film with uniform thickness can be readily prepared with the EPD method using isopropanol as solvent and iodine as dispersant. As EPD electrode, the NiO–YSZ substrate was covered with a graphite layer to obtain enough electric conductivity. A series of experiments, such as suspension concentration, sintering shrinkage, and so on, were conducted in order to optimize the EPD technique. A planar-type SOFC was fabricated using La0.4Sr0.6Co0.2Fe0.8O3 (LSCF) as the cathode and YSZ film deposited onto the NiO–YSZ anode substrate as the electrolyte. The fuel cell exhibited an open circuit voltage of about 1.0V and a maximum power density of 440mW/cm2 at 900°C. Thus, the EPD method was a suitable technology for the formation of gas-tight YSZ film. [Copyright &y& Elsevier]

Abstract: A new mixed valence perovskite oxide Eu0.62K0.38TiO3 was synthesized using a high pressure and high temperature method. XRD analysis showed that the sample is single phase and has a cubic structure. EPR and Mössbauer measurements indicated that the Eu ions are in mixed valence state between +3 and +2 in the sample. The high pressure and high temperature synthesis method has some advantages. [Copyright &y& Elsevier]

Abstract: PrGa0.9Mg0.1O3 was synthesized by using a citric acid method. Compared with the sample prepared by the solid state technique, the sample synthesized by the citric acid method crystallized at a lower temperature. X-ray diffraction data indicated that a pure orthorhombic phase was formed at 1300°C. PrGa0.9Mg0.1O3 showed a conductivity of 0.076S/cm at 800°C and an activation energy of 32.98kJ/mol. Its average thermal expansion coefficient from 600 to 1000°C was 11.9×10−6 K−1, which well matches with the NiO/YSZ anode and doped LaMnO3 cathode. A power density of 55mW/cm2 and a short circuit current density of 200mA/cm2 were obtained at 900°C in a single fuel cell experiment by using PrGa0.9Mg0.1O3 as an electrolyte. This could be attributed to the existence of hole conduction in the sample. [Copyright &y& Elsevier]

Abstract: By using a high-pressure and high-temperature method, perovskite oxides of the type La1-xKxTiO3 (x = 0.30, 0.35, 0.40, 0.45, 0.50) with mixed valence state were synthesized. This new synthesis route has several advantages. XRD analysis shows a cubic cell for the samples. XPS of the surface and EPR measurements indicate that the Ti ions have a mixed valence of 3+ and 4+ and that A-cation vacancies exist in the samples. As x increases, the amount of Ti3+ ions and A-cation vacancies decreases. The valence state of the Ti ions can be altered by changing both pressure and temperature. [Copyright &y& Elsevier]

A series of new Ni–Cu–YSZ cermet made of oxide raw materials was employed as the anode of a SOFC. The reducing properties of these materials were first investigated. The open circuit voltage was over 1.1 V, and the output power density was about 33–43 mW/cm2 at 900°C. Altering the fuel gas between H2 and city coal gas shows that the output voltage and power are affected by fuel, and the response of fuel cell to the fuel gas is rapid. When pitch exists in the fuel gas, a tar-liked carbon is deposited on the Al2O3 tubes of the cell but not on the anode. It has been proved that the anode with Cu has a self-cleaning function. [Copyright &y& Elsevier]

A key obstacle to commercialization of solid oxide fuel cells is the sluggish oxygen reduction on the cathodes. In this work, a series of calcium-doped La 0.5- x Ca x Ba 0.5 FeO 3-δ (x = 0–0.2) are developed as highly active cathode materials and systematically evaluated their physicochemical properties. Among all the components, the La 0.35 Ca 0.15 Ba 0.5 FeO 3-δ cathode delivers the minimal polarization resistance (0.059 Ω cm2) and maximum power densities (452 mW cm−2) at 800 °C, and possesses better stability after long-term operation. Based on the analysis results of electrochemical impedance spectra and distribution of relaxation time, the adsorption process of oxygen on the La 0.35 Ca 0.15 Ba 0.5 FeO 3-δ cathode surface is proved to be the major rate-limiting step. These results suggest that La 0.35 Ca 0.15 Ba 0.5 FeO 3-δ can be used as a candidate cathode material for solid oxide fuel cells. • Ca-doped La 0.5−x Ca x Ba 0.5 FeO 3-δ powders are synthesized and characterized. • The La 0.35 Ca 0.15 Ba 0.5 FeO 3-δ cathode shows excellent ORR catalytic activity. • The lowest R p of 0.059 Ω cm2 is achieved at 800 °C. [ABSTRACT FROM AUTHOR]

Abstract: The GdBaCo2O5+δ –Sm0.2Ce0.8O1.9 (GBCO–SDC) composite cathodes were prepared, their thermogravimetric measurement, thermal expansion coefficient (TEC), electrical conductivity and electrochemical performance were studied as function of temperature and SDC content. The adjustment of TEC to electrolyte, which is one of the main problems of GBCO cathode, could be achieved to lower TEC values with more SDC addition, while maintaining reasonable high electrical conductivity. By means of DC polarization and AC impedance spectroscopy, the electrochemical performance of GBCO–SDC composite cathodes on SDC electrolyte was examined. Results indicated that the proper addition of SDC could improve the performance of GBCO cathode. The optimum content of SDC in the composite cathodes was 40wt.% with the polarization resistance (Rp) of 1.39Ωcm2 at 500°C, which was significantly lower than that of pure GBCO cathode (7.26Ωcm2). [Copyright &y& Elsevier]

In this article, we propose a simple redox process to in-situ create a cellular architecture on Ni solid sheet by the direct oxidization (O 2 ) and subsequent reduction (H 2 ) at 750 °C. Nanocrystalline Ni(OH) 2 is fabricated on the micro-porous Ni sheet (MPNS) using cathodic electrodeposition method to form a MPNS-Ni(OH) 2 electrode for supercapacitor. The obtained results indicate that the created micro-porous architectures expand the contact interfaces between the Ni(OH) 2 and Ni substrate and enhance its supercapacitor performance and cyclic stability. [ABSTRACT FROM AUTHOR]

In this paper, a composite cathode material consisted of 70 wt % La 2 NiO 4+δ and 30 wt % Ce 0.55 La 0.45 O 2-δ (LNO-LDC) was synthesized by co-synthesized method. The LNO-LDC composite cathode was coated on Sm 0.2 Ce 0.8 O 1.9 electrolyte and its electrochemical performance was evaluated. The co-synthesized LNO-LDC cathode showed excellent electrochemical performance, demonstrating a polarization resistance of 0.06 Ω cm 2 at 800 °C, which is significantly lower than that of physically mixed LNO-LDC composite cathode under the same operating condition. The enhanced electrochemical performance was mainly due to the reduced particle size and improved dispersion uniformity of the two phases, leading to increase of the two phase boundary (2 PB) and triple-phase boundary (3 PB). Furthermore, impedance spectra under various oxygen partial pressure determined that the rate-determining step of the co-synthesized LNO-LDC cathode is the charge transfer process. The obtained results indicated that co-synthesized method is a simple and effective method to fabricate high-performance LNO-LDC composite for intermediate temperature solid oxide fuel cells (IT-SOFCs). [ABSTRACT FROM AUTHOR]

Sulfur poisoning and subsequent oxidative regeneration of La 0.75 Sr 0.25 Cr 0.5 Mn 0.5 O 3−δ (LSCrM) anode by pure O 2 were studied using a model solid oxide fuel cell with yttria-stabilized zirconia (YSZ) electrolyte. Utilization of H 2 fuel containing 50 ppm (v) of H 2 S was found to result in increasing polarization resistance of LSCrM anode and degradation of overall cell performance, mainly due to absorption of sulfur and formation of metal sulfides. The electrochemical performance of the cell can be recovered after first two poisoning-oxidative regeneration cycles. Oxidative treatment made it possible to remove the absorbed sulfur and to oxidize metal sulfide. Progressing microstructure changes in LSCrM anode with increasing number of alternative poisoning-regeneration cycles lead however to irreversible degradation. [ABSTRACT FROM AUTHOR]

Copper-doped Pr 0.6 Sr 0.4 Fe 0.8 Cu 0.1 W 0.1 O 3-δ (PSFCuW) as a symmetric electrode material is investigated for La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ (LSGM)-based symmetric solid oxide fuel cells (SSOFCs). The effect of Cu-doping on stability and mechanism of hydrogen oxidation reaction (HOR) and oxygen reduction reaction (ORR) is investigated and analyzed. Fe partially replaced by Cu on the B-site could also keep the phase structure stable after treatment under reducing conditions and improve the electrical conductivity, which reaches 30.3 and 0.78-1 under oxidizing and reducing conditions at 800 oC, respectively. The distribution of relaxation times (DRT) indicates that the rate-limiting step processes under oxidation conditions are oxygen adsorption and diffusion, while hydrogen adsorption and charge transfer have important influences on the rate-limiting step under reduced atmospheres, respectively. Finally, the LSGM-supported SSOFC (PSFCuW|LSGM|PSFCuW) shows excellent stability and reversibility. These results imply that PSFCuW is an up-to-coming symmetric electrode material for application in SSOFCs. • Cu-doped PSFW as symmetric electrodes are investigated for SSOFCs systematically. • Mechanisms of HOR and ORR are analyzed using distribution of relaxation times. • The symmetric electrodes exhibit different electro-catalytic ability. • The cell with different symmetric electrodes shows considerable stability and reversibility. [ABSTRACT FROM AUTHOR]

The design of active anode materials with abundant active sites for fuel oxidation reaction is highly desirable. In-situ exsolution of nanoparticles from perovskite oxides is an effective approach to maintain its nanoscale dimensions and provide efficient active sites. Herein, a promising anode material decorated with copper-iron bimetallic nanoparticles is prepared by in-situ exsolution from A-site deficient Sr 1.9 Fe 1.5 Mo 0.5−x Cu x O 6-δ double perovskite. With the doping of Cu, the agglomeration of iron nanoparticles is highly inhibited under reducing environment and copper-iron bimetallic nanoparticles can be uniformly formed. Through high temperature reduction, Sr 1.9 Fe 1.5 Mo 0.5 O 6-δ substrate is transferred to heterostructure consisting of a Ruddlesden-Popper phase (Sr 3 FeMoO 6.5) and a perovskite phase. The in-situ exsolved copper-iron bimetallic nanoparticles on the heterostructure can provide abundant active sites for fuel oxidation and lead to an improvement of polarization resistance from 0.41 Ω·cm2 to 0.22 Ω·cm2 at 800 °C under H 2. In addition, the maximum power density is increased to 574 mW cm−2, which is about 37% higher than that of Sr 1.9 Fe 1.5 Mo 0.5 O 6-δ. The present study provides a potential strategy for developing efficient anode materials for solid oxide fuel cells. • The design of active anode materials with abundant active sites. • With the doping of Cu, the agglomeration of iron nanoparticles is highly inhibited. • Cu Doped SFM Improves Electrical Conductivity in Oxidation and Reduction Atmospheres. • The maximum power density of SFMC0.1 is about 37% higher than that of SFMC0. [ABSTRACT FROM AUTHOR]

Abstract: Red Gd2O3:Eu nanophosphors were prepared by novel sucrose-assisted combustion method. The sucrose hydrolysis and complexing procedures were discussed by the Fourier transform infrared spectroscopy (FTIR) analysis. The effect of sucrose-to-metal ratio (S:M) on morphology and luminescence intensity of Gd2O3:Eu nanocrystals were investigated. And the optimum ratio was found to be S:M=7:1, as confirmed by the results of scanning electron microscope (SEM), transmission electron microscope (TEM) and photoluminescence (PL) measurements. The highest photoluminescence emission from the particles obtained at S:M=7:1 was about 85% of the commercial red phosphors. [Copyright &y& Elsevier]

Abstract: The effect of Fe doping (0≤ y ≤0.10) in Mn site was studied for the colossal magnetoresistance material La5/6Na1/6MnO3. The same size of Fe3+ and Mn3+ causes no structure change in the series, yet conduction and ferromagnetism have been consistently suppressed by Fe doping. Doping with Fe causes no dominant lattice effects. It depopulates the hopping electrons and weakens the double exchange. ZFC and FC magnetization curve at 0.01T field shows irreversibility. The temperature dependence of resistivity shows that all samples undergo a transition from paramagnetic to ferromagnetic with the decrease of temperature. However, for y =0.10 sample, two obvious peaks are observed in the magnetoresistance versus temperature curve at 5T field. The high-field MR effect may have its origin in a small canting of the manganese moments inside each domain even for H > H s. The canting angle becomes smaller and therefore electrons transfer more easily between pairs of Mn3+ and Mn4+ions under high field. This will lead to a MR effect. [Copyright &y& Elsevier]

Developing efficient and nonprecious electrocatalysts for oxygen evolution reaction (OER) is crucial for the hydrogen generation via water splitting. Here we report the direct growth of heterostructural Ni 2 P–Fe 2 P hybrid electrocatalysts on NiFe foams. The redox engineered NiFe foam (rNF) significantly enhances the OER performance. Among prepared catalysts, Ni 2 P–Fe 2 P/rNF performs the highest OER activity, driving the current densities of 10 and 100 mA cm−2 at low overpotentials of 218 and 270 mV in 1 M KOH, respectively. Meanwhile, it can maintain 100 mA cm−2 for 24 h without obvious degradation. The morphology and composition of NFP/rNF after OER test were carefully studied. This work suggests that self-supported bimetal phosphides of NFP/rNF is an efficient and durable electrode material for water oxidation. Heterostructural Ni2P-Fe2P hybrid electrocatalysts were direct grown on NiFe foams, which show excellent oxygen evolution activity and stability. Image 1 • The formation of micro-sized pores on the skeleton of NiFe foam (NF) substrate can enlarge surface area. • The heterogeneous Ni2P-Fe2P structure provides plentiful active sites for OER. • The Ni2P-Fe2P/ rNF foam exhibits an extraordinary electro catalytic performance. [ABSTRACT FROM AUTHOR]

In this work, we report FeCo 2 O 4 - x Ce 0.8 Sm 0.2 O 1.9 (x = 0, 30, 40, 50, 60, 70 wt%), catalyst/electrolyte composite oxides, as cathode materials for application in solid oxide fuel cells. Herein a systematic investigation represents the effect of Ce 0.8 Sm 0.2 O 1.9 incorporation on physical and electrochemical properties. The obtained results indicate that the addition of Ce 0.8 Sm 0.2 O 1.9 to form FeCo 2 O 4 –Ce 0.8 Sm 0.2 O 1.9 composite material plays a key role in physical and electrochemical properties. Among all the components, the FeCo 2 O 4 –60Ce 0.8 Sm 0.2 O 1.9 composite cathode has the lowest polarization resistance of ∼0.094 Ω cm2 at 800 °C in air, which is much smaller than that of the FeCo 2 O 4 cathode (4.18 Ω cm2). In comparison with the FeCo 2 O 4 cathode, the FeCo 2 O 4 –60Ce 0.8 Sm 0.2 O 1.9 composite cathode has a better electrocatalytic activity and a larger power density of 397 mWcm−2 based an electrolyte-supported single-cell configuration at 800 °C. The oxygen partial pressure dependence studies indicate that rate limiting steps of the FeCo 2 O 4 –60Ce 0.8 Sm 0.2 O 1.9 composite cathode are the adsorption process of the molecular oxygen on the electrode surface and the charge-transfer process. In consequence of these superior properties, it is reasonable to believe that the FeCo 2 O 4 –60Ce 0.8 Sm 0.2 O 1.9 oxide has great potential to become a cathode material for solid oxide fuel cells. Image 1 • The FeCo 2 O 4 composite spinel oxides are first applied as solid oxide fuel cell cathode materials. • A novel FeCo 2 O 4 spinel composite cathode materials show better high temperature chemical compatibility and catalytic activity. • The polarization resistance of FeCo 2 O 4 –60Ce 0.8 Sm 0.2 O 1.9 composite cathode is reduced down to 0.094 Ω cm2 at 800 °C. [ABSTRACT FROM AUTHOR]

In this study, the valence state of Pr in Mg doped PrGaO3 perovskites was investigated. It is found that Pr4+ ions are created in samples doped with low-valence ions, for example, with Mg2+. The color of the doped samples changes from black to light green after being treated in H2 atmosphere, which shows that the Pr4+ ions in the sample are reduced to Pr3+ ions. The open circuit voltage of the solid oxide fuel cell (SOFC) using PrGa0.95Mg0.05O3 as the electrolyte increases with time and the X-ray photoelectron spectroscopy (XPS) data of PrGa0.9Mg0.1O3 also show the existence of Pr4+ ions in Mg doped PrGaO3. [Copyright &y& Elsevier]