Search

To determine the optimal combination of NiO and Ba 0.8 Sr 0.2 Ce 0.6 Zr 0.2 Y 0.2 O 3-δ (BSCZY) for fabricating anode materials, Ni-BSCZY samples were prepared using the solid state reaction process. The porous structure of anode substrates not only provides mechanical strength to the fuel cells to enable fuel gases to flow to the electrolyte membrane but also creates an excess surface area on which to form a larger triple-phase boundary when NiO is added to the anode sample. The effect of NiO content on the microstructures, surface area, and electric conductivity of these Ni-BSCZY (NiO55-BSCZY, NiO60-BSCZY, and NiO65-BSCZY) anode materials were systematically investigated using X-ray diffraction, scanning electron microscopy, an analytic technique based on the Brunauer–Emmett–Teller surface area theory, and four-probe conductivity analysis. In addition, three anode-supported cells containing identical electrolytes but various combinations of NiO and BSCZY anode materials were fabricated and used for performance and electrochemical impedance measurement. The results revealed that the reactive surface area of the anode in contact with the electrolyte plays a crucial role in total cell performance. The cell containing the anode material (NiO60-BSCZY) with the highest surface area of 6.91 m 2 g −1 and the lowest total resistance of 2.19 Ω cm 2 exhibited the highest power density of 169.2 mW cm −2 at 800 °C.

In the present study, a nanocomposite cathode comprising Fe rich La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF) based pervoskite semiconductor oxide and Sm-Gd co-doped ceria rich Ce 0.8 Sm 0.1 Gd 0.1 O 1.90 (CSGO) in the ratio of 1:1 has been successfully synthesized by a simple glycine nitrate auto combustion method. The structural properties of the two phase nanocomposite were evaluated by X-ray diffraction and Raman spectroscopy. A detailed electrical properties of co-doped LSCF-CSGO nanocomposites have been studied with a comparison of LSCF added with 10 mol% and 20 mol% Gd singly doped ceria (LSCF-GDC10 and LSCF-GDC20) nanocomposites as a function of temperature in the range of 673–1073 K at air atmosphere by AC impedance spectroscopy. The total electrical conductivity of the co-doped LSCF-CSGO nanocomposites has been found to be 0.043 S cm −1 at 973 K which is higher than that of the LSCF composite containing singly doped compositions. The Sm co-doping in GDC phase has effectively helped to reduce the undesired electronic conduction produced in the doped ceria as the electron concentration of LSCF-CSGO was found to be − 2.62 × 10 15 cm −3 which was lower than the electron concentration of LSCF containing singly doped nanocomposite (LSCF-GDC20, − 2 ×10 16 cm −3 ) estimated by Hall-Effect measurement. The activation energy of LSCF-CSGO nanocomposite has been found to be 0.05 eV for the oxygen reduction reaction by temperature dependent Arrhenius equation. The improved electrical properties in terms of high ionic conductivity and low activation energy have been achieved through the incorporation of Sm into GDC10 electrolyte phase in LSCF nanocomposite. The combustion synthesis method has also effectively helped to produce microstructure containing large grain size (~ 6 µm) which is beneficial for enlarging triple phase boundary (TPB) area of cathodes utilized in solid oxide fuel cells (SOFC) operated at reduced/intermediate temperature (673–973 K).

An atmospheric-pressure plasma jet (APPJ) is applied to prepare porous perovskite materials, particularly of lanthanum strontium manganite La0.5Sr0.5MnO3 (LSM551) oxide powder and film. LSM nano powder around 50.0 nm is obtained, and characterized by X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscope. A spherical morphology with hydrangea-like shape is observed as associates to the pure tetragonal phase. LSM film is deposited onto yttria-stabilized zirconia (YSZ) electrolyte-support substrate as cathode layer for the operation in a solid oxide fuel cell at 600–900 °C operating temperatures. A series of symmetrical cells possessing high exchange current density of 30.12 mA/cm2 at 800 °C. The prepared samples are assessed as an object to discover the diffusion mechanism of oxygen pathways for LSM/YSZ system based on the microstructural (particles size, and porosities) and electrochemical (kinetic and impedance) data. The mechanism of oxygen pathways is directly associated with the triple phase boundary lengthiness, in which the surface and bulk pathways occurring in APPJ-prepared LSM layer on YSZ lead to an increasing in activity of oxygen reduction reaction. Moreover, a fabrication of desirable ternary metal oxide, LSM, with highly porous structure via an advance-innovative APPJ preparation is outlined.

In this study，nanocomposites of LaCePr-oxide (LCP) and Ni 0.8 Co 0.15 Al 0.05 LiO 2-δ (NCAL) with different contents of polyvinylidene fluoride (PVDF) were prepared and applied to solid oxide fuel cells. The composite materials were characterized by X-ray diffraction analysis (XRD), scanning electron microscope (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and electrochemical impedance spectrum (EIS). The effect of PVDF concentration on the conductivity and performance of the fuel cells was investigated. It was found that PVDF plays a template role of pore forming in the nanocomposites, and the changed microstructure by as-formed pores greatly influences the electrochemical property of the nanocomposites. The cell with 3 wt% PVDF heat-treated at 210 °C achieved the highest power density of 982 mW cm −2 at 520 °C, which enhanced performance by more than 57% than when no heat-treatment was implemented. It is 66% higher than the cell with no PVDF and no heat-treatment. Pores formed by PVDF after heat-treatment enlarged the triple phase boundary (TPB), which results in improved fuel cell performance.

Perovskite-type oxide La0.75Sr0.25Cr0.5Mn0.5O3−δ (LSCM) as sensing electrode for detection of NO2 was fabricated by impregnating the porous Ce0.9Gd0.1O1.95 (CGO) backbone with LSCM precursor solution. The sensing performances of the amperometric type sensor prepared under different conditions were investigated. The results indicated that the sensitivity of the sensor was strongly dependent on the LSCM loading level, CGO porous layer thickness, polarization potential and LSCM fabricating temperature. The influences of the LSCM loading and porous backbone thickness on the sensing performance of the sensor suggested that the porous structure of CGO backbone was not only appropriate for preparing nano-structure LSCM sensing electrode by impregnation, but also helpful for the mass transfer of NO2 to the triple phase boundary. When the applied potential moved negatively, the response current and sensitivity increased. Increasing the calcining temperature could improve the adhesion of LSCM to CGO backbone which was in favor of better sensing performance while increasing the LSCM particle size which resulted in the dropping of response current and sensitivity.

To improve the performance of the cathode, many groups have studied the relationship between the cathode microstructure and the electrochemical performance. In this study, a porous La 0.8 Sr 0.2 MnO 3± δ (LSM) cathode film with primary particles of under 10 nm diameters was prepared by aerosol flame deposition (AFD). The AFD technique was applied to synthesize the spherical particles and dense LSM thin film. The cathode performance was improved, and the polarization resistance was decreased by extending the active triple phase boundary. The electrochemical characteristics were investigated in the temperature range of 600–900 °C and oxygen partial pressure range of 0.1–1.0 atm. For oxygen reduction reaction on the LSM cathode, it was turned out that both oxygen atom diffusion and oxygen ion transfer from the three phase boundary to the yttria-stabilized zirconia electrolyte lattice were the rate-determining steps with comparable contributions. The polarization resistance of the prepared LSM film decreased from 206 to 1.7 Ω cm 2 with increasing temperature from about 600 to 900 °C and the activation energy was 1.48 eV.

This paper reports a facile microwave-assisted complex-gel auto-combustion method synthesis of La1.67Sr0.33NiO4 and YSZ composite powders and their utilization for the fabrication of high performance potentiometric NOx sensors. The synthesized composite powders with different YSZ concentrations (5 wt%, 10 wt% and 20 wt%) were characterized using Fourier transformed infrared (FTIR) spectrum and X-ray diffraction (XRD). The gas sensing property of the composites to NO was tested at temperatures ranging from 400 °C to 600 °C. The sensor fabricated with 10 wt% YSZ addition composite sensing electrode exhibited the biggest response (about 27 mV for 700 ppm NO) at 400 °C. Moreover, the response time and recovery time were within 4–18 s and 6–35 s, respectively. The enhanced gas sensing performance of the sensor to NO may be attributed to the larger superficial area of triple phase boundary. This work demonstrated that the simply synthesized La1.67Sr0.33NiO4 and YSZ composite powders can be effectively used for the fabrication of potentiometric NOx sensors.

The influence of electrospinning parameters including polymer content and applied voltage on microstructural features of 8 mol% Y 2 O 3 stabilized ZrO 2 (8YSZ) nanofiber were investigated in this work. Cathode catalyst of nano-La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3−δ (LSCF) particles mixed with nano-8YSZ electrolyte fiber was coated onto 8YSZ electrolyte to study its catalytic property, compared to the powder cathode. The experimental results show that a uniform 8YSZ nanofiber of 100 nm diameter could be spun at the concentration of polyvinyl pyrrolidone (PVP) of approximately 9.89 wt% and at an applied voltage of 20 kV. The exchange current of the LSCF–8YSZ nanofiber composite cathode which is 145.06 mA/cm 2 is much better than that of the LSCF–8YSZ powder cathode which is 81.82 mA/cm 2 . It is due to the increase of triple phase boundary by fiber structure to increment oxygen reduction reaction.