Enhanced electrochemical properties of Bi-layer La0.5Sr0.5CoO3−δ cathode prepared by a hybrid method

Bi-layer La_0.5Sr_0.5CoO_3−δ (LSCO) cathodes are processed by a hybrid method that combines a seed layer prepared by a pulsed laser deposition (PLD) technique and a conventional cathode layer (∼7 μm in thickness) by a screen printing method. By inserting the PLD seed layer with the thickness of ∼500 nm or less, robust cathode films with desired microstructure and excellent adhesion properties with the underlying electrolyte layer, are successfully fabricated. The area specific resistance (ASR) of the hybrid cathode layers decreases about 5 times compared with that of the single layer cathode films prepared by the conventional screen printing method. The hybrid approach provides a cost-effective way to fabricate thick cathode films with significantly enhanced electrochemical properties for solid oxide fuel cells (SOFCs).     

氯氧化锆生产排放碱液及硅渣制层状结晶二硅酸钠研究

利用氯氧化锆生产过程中排放的稀碱液、酸性硅渣辅加少量石英砂制备δ-层状结晶二硅酸钠,产品达到国家GB/T19421-2003标准;同时可从硅渣中回收附加值高的锆英砂和偏锆酸钠等锆组分返回氯氧化锆生产系统二次使用.该工艺具有资源利用合理、产品效益显著的特点.     

Novel doped barium cerate–carbonate composite electrolyte material for low temperature solid oxide fuel cells

A composite of a perovskite oxide proton conductor (BaCe_0.7Zr_0.1Y_0.2O_3−δ, BCZ10Y20) and alkali carbonates (2Li₂CO₃:1Na₂CO₃, LNC) is investigated with respect to its morphology, conductivity and fuel cell performance. The morphology shows that the presence of carbonate phase improves the densification of oxide matrix. The conductivity is measured by AC impedance in air, nitrogen, wet nitrogen, hydrogen, and wet hydrogen, respectively. A sharp increase of the conductivity at certain temperature is seen, which relates to the superionic phase transition at the interface phases between oxide and carbonates. Single cell with the composite electrolyte is fabricated by dry-pressing technique, using nickel oxide as anode and lithiated nickel oxide as cathode, respectively. The cell shows a maximum power density of 957 mW cm⁻² at 600 °C with hydrogen as the fuel and oxygen as the oxidant. The remarkable proton conductivity and excellent cell performance make this kind of composite material a good candidate electrolyte for low temperature solid oxide fuel cells (SOFCs).     

Instrumental Textural Characteristics of Restructured Carrot Cubes

Studies were carried out on the instrumental textural evaluation of restructured carrot cubes. The experiment was conducted by incorporating different levels of alginate, glucono delta lactone (GDL), and calcium salt to the carrot pulp. Investigations showed that as pulp level increased from 0 to 90%, there was a corresponding decrease in failure stress, failure strain, and deformability modulus. Instrumental textural profile analysis (TPA) parameters viz. hardness, springiness, gumminess, cohesiveness, chewiness, and resilience also showed a similar trend. Effect of formulation variables, i.e., alginate, GDL, and calcium salt on hardness (response variable) were evaluated by the application of response surface methodology. All the three ingredients showed a significant (P < 0.05) influence on hardness of carrot gel. Heat treatment of restructured carrot samples resulted in an increased hardness, cohesiveness, gumminess, and chewiness while springiness, cohesiveness, and resilience decreased. The data indicated that the shrinkage during thermal treatment may be responsible for the change in textural attributes. The authors concluded that a thermally stable restructured product with appreciable textural integrity can be obtained from carrot pulp.     

La substituted Sr2MnO4 as a possible cathode material in SOFC

Sr_2−xLa_xMnO_4+δ (x = 0.4, 0.5, 0.6) oxides were studied as the cathode material for solid oxide fuel cells (SOFC). The reactivity tests indicated that no reaction occurred between Sr_2−xLa_xMnO_4+δ and CGO at annealing temperature of 1000 °C, and the electrode formed good contact with the electrolyte after being sintered at 1000 °C for 4 h. The total electrical conductivity, which has strong effect on the electrode properties, was determined in a temperature range from 100 to 800 °C. The maximum value of 5.7 S cm⁻¹ was found for the x = 0.6 phase at 800 °C in air. The cathode polarization and AC impedance results showed that Sr_1.4La_0.6MnO_4+δ exhibited the lowest cathode overpotential. The area specific resistance (ASR) was 0.39 Ω cm² at 800 °C in air. The charge transfer process is the rate-limiting step for oxygen reduction reaction on Sr_1.4La_0.6MnO_4+δ electrode.     

Novel nano-network cathodes for solid oxide fuel cells

A novel nano-network of Sm_0.5Sr_0.5CoO_3−δ (SSC) is successfully fabricated as the cathodes for intermediate-temperature solid oxide fuel cells (SOFCs) operated at 500–600 °C. The cathode is composed of SSC nanowires formed from nanobeads of less than 50 nm thus exhibiting high surface area and porosity, forming straight path for oxygen ion and electron transportation, resulting in high three-phase boundaries, and consequently showing remarkably high electrode performance. An anode-supported cell with the nano-network cathode demonstrates a peak power density of 0.44 W cm⁻² at 500 °C and displays exceptional performance with cell operating time. The result suggests a new direction to significantly improve the SOFC performance.     

Chemical stability and hydrogen permeation performance of Ni–BaZr0.1Ce0.7Y0.2O3−δ in an H2S-containing atmosphere

Composite membranes based on Ni and Zr-doped BaCeO₃ are promising for hydrogen separation. Such composites show high proton conductivity and adequate chemical stability in H₂O and CO₂, but may be unstable in H₂S. In this work, the hydrogen permeation performance of Ni–BaZr_0.1Ce_0.7Y_0.2O_3−δ was measured in an H₂S-containing atmosphere at 900 °C. The hydrogen permeation flux began to degrade in 60 ppm H₂S and decreased by about 45% in 300 ppm H₂S. After hydrogen permeation tests, X-ray diffraction analysis revealed the formation of BaS, doped CeO₂, Ni₃S₂ and Ce₂O₂S. Analysis of the microstructure and phase composition, and results of thermodynamic calculations suggest that reaction between H₂S and doped BaCeO₃ caused the performance loss of the Ni–BaZr_0.1Ce_0.7Y_0.2O_3−δ.     

Synthesis,electrical and electrochemical properties of Ba0.5Sr0.5Zn0.2Fe0.8O3−δ perovskite oxide for IT-SOFC cathode

The Ba_0.5Sr_0.5Zn_0.2Fe_0.8O_3−δ (BSZF) complex oxide with cubic perovskite structure was synthesized and examined as a new cobalt-free cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The electrical conductivity was relatively low with a peak value of 9.4 S cm⁻¹ at about 590 °C, which was mainly caused by the high concentration of oxygen vacancy and the doping of bivalent zinc in B-sites. At 650 °C and under open circuit condition, symmetrical BSZF cathode on Sm-doped ceria (SDC) electrolyte showed polarization resistances (R_p) of 0.48 Ω cm² and 0.35 Ω cm² in air and oxygen, respectively. The dependence of R_p with oxygen partial pressure indicated that the rate-limiting step for oxygen reduction was oxygen adsorption/desorption kinetics. Using BSZF as the cathode, the wet hydrogen fueled Ni + SDC anode-supported single cell exhibited peak power densities of 392 mW cm⁻² and 626 mW cm⁻² at 650 °C when stationary air and oxygen flux were used as oxidants, respectively.     

硬岩层对岩移参数的影响规律

在整理和分析大量实测资料基础上 ,应用数理统计方法对覆岩中硬岩层对岩移参数的影响进行了研究 ,找出了硬岩层在覆岩中所占比例与岩移参数统计规律 ,对开采沉陷的进一步研究具有重要的意义。     

牦牛服装革制造的理论与实践

本文系统地总结了拉萨皮革厂生产牦牛服装革的经验,并从生皮化学、组织学、物理化学等学科深度阐明制革理论。