NO2 adsorption behaviour on LaFeO3 electrodes of YSZ-based non-nernstian electrochemical sensors

X-ray photoelectron spectroscopy (XPS) was used to examine the NO₂ adsorption behaviour on the LaFeO₃ and Pt electrodes of planar yttria stabilized zirconia non-Nernstian gas sensors. The electrochemical sensors were exposed to the same gas atmosphere containing 1000 ppm NO₂ at 650°C. XPS of the as-prepared sensors and sensors after exposure to NO₂ revealed bonded nitrogen peaks on the surface of the semiconducting oxide but no nitrogen peaks on the Pt electrode. Therefore, NO₂ adsorption on a LaFeO₃ electrode plays an important role in the NO₂ detection mechanism.     

Simulation of capacity loss in carbon electrode for lithium-ion cells during storage

A mathematical model was developed which simulates the self-discharge capacity losses in the carbon anode for a SONY 18650 lithium-ion battery. The model determines the capacity loss during storage on the basis of a continuous reduction of organic solvent and de-intercalation of lithium at the carbon/electrolyte interface. The state of charge, open circuit potential, capacity loss and film resistance on the carbon electrode were calculated as a function of storage time using different values of rate constant governing the solvent reduction reaction.     

Spectroscopic investigation,cage occupancy,and gas storage capacity of hydroquinone clathrates formed with H<Subscript>2</Subscript>S-N<Subscript>2</Subscript> and COS-N<Subscript>2</Subscript> binary gas mixtures

The objective of this investigation was to determine whether hydroquinone (HQ) can form clathrate compounds with two sulfides (hydrogen sulfide (H₂S) and carbonyl sulfide (COS)) at their diluted concentrations. Hydroquinone samples obtained at ambient temperature and at two pressures (40 and 80 bar) for binary gas mixtures consisting of H₂S-N₂ and COS-N₂, were analyzed using solid-state ¹³C NMR and Raman spectroscopy. An elemental analyzer was also used to obtain quantitative information regarding the kind and amount of gas captured in the solid samples. Results show that H₂S can be concentrated within the solid clathrate from H₂S-containing gas, while COS is little captured after reaction with the COS-containing gas. This suggests that the HQ clathrate can be used to remove H₂S, and that selective separation can be achieved when two sulfides of H₂S and COS coexist. On the basis of the calculated cage occupancies of the gas components in the solid clathrate, the enclathration preference of the gas components used in this research was found to be the order of H₂S>N₂>COS.     

Electrochemical synthesis of birnessite-type layered manganese oxides for rechargeable lithium batteries

Layered manganese dioxide (MnO₂) films intercalated with Li⁺, Na⁺ or Mg²⁺ ions were synthesized by a one-step electrochemical method. The electrodeposition was potentiostatically performed by applying an anodic potential of 1.0 V vs. Ag/AgCl in an aqueous MnSO₄ solution containing a perchlorate salt of the cation. The electrodeposited oxide films have a birnessite-type layered structure with alkali cations and water molecules between manganese oxide layers. The galvanostatic charge–discharge experiments performed in 1 M LiPF₆-DME/PC solution indicated that the Mg²⁺-intercalated MnO₂ electrode exhibits an initial discharge capacity as large as 140 mAh g⁻¹ and it shows a better capacity retention during cycling as compared with the Li⁺- or Na⁺-intercalated MnO₂ electrode.     

A review of gas diffusion layer in PEM fuel cells: Materials and designs

The gas diffusion layer (GDL) plays a key role on reactant gas diffusion and water management in proton exchange membrane (PEM) fuel cells. This paper reviews recent developments of single- and dual-layer GDLs for PEM fuel cells and various materials and approaches used for development of novel GDL. A variety of carbon- and metal-based macroporous substrates are presented. Hydrophobic treatments using different fluorinated polymers are addressed. Engineering parameters which control the performance of microporous layer such as carbon treatment, wettability, thickness, and microstructure are also reviewed. In addition, future prospects for development of new GDL development are discussed.     

Development of nonequilibrium pressurizer model with noncondensable gas

To investigate thermal–hydraulic characteristics of a steam–gas pressurizer in the integral type reactor, the steam–gas pressurizer model based on the two-region nonequilibrium concept was developed and introduced into RETRAN-3D/INT code. The model includes an explicit solution method for the one-dimensional governing equations and the equation of the state solution method to determine the thermal–hydraulic state of the steam–gas pressurizer volume. In addition, the wall condensation model based on the diffusion layer modeling was included to consider the effect of the noncondensable gas. The developed model was verified with the results from the pressurizer insurge experiment conducted at Massachusetts Institute of Technology. From the verification results, it was concluded that the developed steam–gas pressurizer model can sufficiently predict the pressurizer transient and it can be used as a component model of the one-dimensional system code based on the homogeneous equilibrium model.     

Effect of glass contents on the electrical and sintering property of La0.8Ca0.2CrO3/glass composite interconnects for solid oxide fuel cells

In order to improve the sintering ability and electrical conductivity of La_0.8Ca_0.2CrO₃ (LCC), LCC/glass composite interconnect materials for high temperature solid oxide fuel cells (SOFCs) were studied in this paper. Glass is known as a sintering aid for improving sintering ability. It promotes liquid phase sintering and improves densification during the sintering process. The components of the glass used in this study are B₂O₃, SrO, La₂O₃, SiO₂ and Al₂O₃.The phase stability, microstructure, electrical conductivity and thermal expansion coefficient (TEC) were measured to determine the optimal glass content in the composite materials. All of the tested composite materials showed perovskite structures and dense microstructures. It was found that the addition of up to 5 wt.% glass increased the sintering ability and the electrical conductivity in both air and hydrogen atmospheres. The glass powder enhances the sintering behavior because it acts as a liquid phase sintering aid and the Sr²⁺ ion in glass powder generates and . These lead to improvement in the electrical conductivity of the material. The TEC of the composites indicated compatibility with other cell components. The above results present that LCC/glass composite materials are suitable to be used as interconnects for SOFCs.     

Pure color and stable blue-light emission-alternating copolymer based on fluorene and dialkoxynaphthalene

A new blue-light emitting polymer that alternates between fluorene and alkoxynaphthalene structure has been developed. The fluorene and naphthalene units were highly distorted with an angle of 76.22° according to theoretical calculations. The obtained polymer has a weight average molecular weight of 273,800 with a polydispersity index of 2.35, good solubility and high thermal stability with a T_g of 176 °C. The film photoluminescence (PL) spectrum (405 nm) is consistent with that of solution and the PL spectra of the polymer did not show any peak in the long wavelength region even after annealing for 24 h at 100 °C. The double-layered device with an ITO/PEDOT/polymer/LiF/Al structure has a turn-on voltage of about 5.4 V, maximum brightness of 110 cd/m² and an electroluminescent efficiency of 0.09 cd/A. The OLED generates pure blue EL emission (λ_max = 405 nm) with excellent CIE coordinates (x = 0.15, y = 0.10) as well as stable blue EL emission that is not altered by voltage increase.