Zirconium dioxide-based solid electrolyte as a means of oxidation of organic compounds during isotopic assay of carbon

It is demonstrated that a high-temperature electrochemical reactor on the basis of zirconium dioxide (0.9ZrO₂ · 0.1Y₂O₃) with platinum electrodes may be promising as a device for preparing samples of organic gases for isotopic assay of carbon. Owing to a high catalytic activity of the surface of a porous platinum coating, it is possible to realize full oxidation of organic gases to stoichiometric oxides at 900–950°C and an oxygen flux equivalent to an electric current of 100 μA and higher. The reproducibility of the results of isotopic assay is better than that yielded by a standard oxidation reactor. Use of the solid-electrolyte reactor in a new device as a sensor makes it possible to simultaneously measure the concentration of organic gases passing through the reactor on the basis of the charge transported by oxygen ions through the wall of a ceramic tube. Simultaneously one can monitor purity of the carrier gas. Original Russian Text ? V.S. Sevast’yanov, E.M. Galimov, N.E. Babulevich, A.A. Arzhannikov, 2007, published in Elektrokhimiya, 2007, Vol. 43, No. 4, pp. 472–478.     

Electrode potentials of electrochemical cells with oxide-conducting solid electrolyte in chemically nonequilibrium gas mixtures

A wide range of electrodes for solid oxide electrolyte cells in chemically nonequilibrium gas media simultaneously containing oxygen and combustible gases is systematically studied. The concentration dependences are investigated for the potential response of electrodes made of conducting oxides, noble metals (platinum, gold, silver), and also composite electrodes containing dispersed oxide semiconductor phases, apart from the main conducting material. Besides, dynamic characteristics of these electrodes are investigated. The studies are performed in the temperature range from 450 to 800°C. The content of combustible gases in the mixture was varied from 10 ppm to 2%. The research results are of interest for development of sensors for combustible gases and for studying kinetics and mechanisms of catalytic oxidation reactions.     

薄膜型中温固体氧化物燃料电池 (SOFC)研制及性能考察

用一种廉价的湿化学方法 ,在Ni_YSZ阳极基膜上制备出致密的YttriaStabilizedZirconia(YSZ)薄膜 .薄膜的厚度约为 10 μm ,致密均匀 ,无裂纹等缺陷 .以Ni_YSZ阳极基膜 ,YSZ薄膜和锶掺杂锰酸镧阴极 (LSM )组装的SOFC单电池 ,在 80 0℃下功率密度达 0 1W /cm2 .研究分析表明 ,YSZ薄膜的IR降 (包括电极 /YSZ薄膜的接触电阻 )较小 ,不是影响电池性能的主要因素 ,大的阳极过电位是影响电池性能的主要因素 .     

The Ag(s)/AgI(s)/graphite solid cell as iodine sensor: speed of response and use of Cs-doped AgI as electrolyte

The time response of a Ag(s)/AgI(s)/graphite(s), I₂(g) galvanic cell as iodine sensor was studied using both pure AgI and CsI doped AgI as electrolyte. The use of doped silver iodide expanded considerably the working temperature. An analytical modeling of the sensor response is presented. Electronic Publication     

Solid-state electrochemical lithium cells with oxide electrodes and composite solid electrolyte

The LiClO₄-Al₂O₃ composite solid electrolyte and solid solutions LiFe _x Mn_2?x O₄ and Li₅Ti₄O₁₂ compositions are synthesized and their physicochemical properties are studied using the x-ray diffraction and electrical measurements. Based on composition 0.5LiClO₄-0.5Al₂O₃, whose conductivity is the highest, first experiments on the elaboration of model electrochemical solid-electrolyte lithium cells with LiMn₂O₄, LiFeMnO₄, LiFe_0.8Mn_0.2O₄, and Li₅Ti₄O₁₂ oxide spinel electrodes are performed.     

Effect of anodic current on carbon dioxide reforming of methane on Pt electrode in a cell with solid oxide electrolyte

The carbon dioxide reforming of methane in a cell with a solid oxygen-conducting electrolyte:

Effect of sulfolane on the morphology and chemical composition of the solid electrolyte interphase layer in lithium bis(oxalato)borate‐based electrolyte

To discuss the source of sulfolane (SL) in decreasing the interface resistance of Li/mesophase carbon microbeads cell with lithium bis(oxalate)borate (LiBOB)‐based electrolyte, the morphology and the composition of the solid electrolyte interphase (SEI) layer on the surface of carbonaceous anode material have been investigated. Compared with the cell with 0.7 mol l^?1 LiBOB‐ethylene carbonate/ethyl methyl carbonate (EMC) (1 : 1, v/v) electrolyte, the cell with 0.7 mol l^?1 LiBOB‐SL/EMC (1 : 1, v/v) electrolyte shows better film‐forming characteristics in SEM (SEI) spectra. According to the results obtained from Fourier transform infrared spectroscopy, XPS, and density functional theory calculations, SL is reduced to Li₂SO₃ and LiO₂S(CH₂)₈SO₂Li through electrochemical processes, which happens prior to the reduction of either ethylene carbonate or EMC. It is believed that the root of impedance reduction benefits from the rich existence of sulfurous compounds in SEI layer, which are better conductors of Li⁺ ions than analogical carbonates. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis and test of palladium-based nanostructured anodic electrocatalysts for hydrogen fuel cells with solid polymer electrolyte

Palladium-based nanostructured electrocatalysts on the Vulcan XC-72 carbon support for fuel cells with solid polymer electrolyte are synthesized and studied. In particular, electrochemical studies of the synthesized catalysts are carried out and membrane-electrode assemblies are assembled on their basis and tested. The test results indicate that platinum can be replaced with palladium in the hydrogen electrode of the fuel cells.     

Electrostatic interaction between a charge-regulated particle and a solid surface in electrolyte solution: effect of cationic electrolytes

The effect of cations on the electrostatic interaction between a negative charge-regulated particle and a solid surface of constant negative potential in electrolyte solution is analyzed. Here, we assume that the rate of approach of a particle to a solid surface is faster than that of the dissociation of the ionogenic groups on the surface of particle. In other words, the effect of the time-dependent dissociation of ionogenic groups on the surface of a particle is taken into account. The result of the present study reveals that, although the solid surface is negatively charged, the presence of cations in the suspension medium has a negative effect on the rate of adhesion. The qualitative behaviors in the variation of the interaction force between a particle and a solid surface as a function of separation distance between them predicted by a kinetic model and the corresponding equilibrium model and constant charge density model are entirely different. The rate of approach of a particle to a solid surface is on the order (constant charge density model)>(kinetic model)>(equilibrium model).     

Melt crystallization and segmental dynamics of poly(ethylene oxide) confined in a solid electrolyte composite

The isothermal melt crystallization and the corresponding segmental dynamics, of a high molecular weight poly(ethylene oxide) (PEO) confined by Li₇La₃Zr₂O₁₂ (LLZO) particles in solid electrolyte composites, were monitored by differential scanning calorimetry (DSC) and dielectric relaxation spectroscopy (DRS), respectively. Our results show that the overall crystallinity is positively correlated with the surface area of LLZO particles. The primary and secondary crystallization processes are identified by a modified Avrami equation, while two dynamic modes, the α relaxation and α′ relaxation, were in the DRS measurements. The results reveal an unambiguous correlation between the primary crystallization and the α relaxation, while a correlation between the second crystallization and the α′ relaxation concurrently exist in the electrolyte composites. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 466–477     

Preparation of polypseudorotaxane composed of linear and cyclic polyethylene oxides and its application to solid polymer electrolyte

The mixture of linear polyethylene glycol with molecular weight of 20,000 (l-PEG_20K) and cyclic polyethylene glycol with molecular weight of 1,000 (c-PEG_1K) was ultrasonicated in acetonitrile. After evaporating the solvent, the residue was analyzed by DSC to show a remarkable decrease of crystallization temperature. Such a large crystallization suppression was not observed when linear polyethylene glycol with molecular weight of 1,000 (l-PEG_1K) was added instead of c-PEG_1K. Further, the mixture of cyclic polyethylene glycols (c-PEG_6K and c-PEG_1K) did not exhibit a significant crystallization suppression. These experimental results indicated that formation of polypseudorotaxane through ultrasonication-assisted ring penetration played an important role in the crystallization suppression. Ionic conductivities of the polypseudorotaxane-based polymer electrolytes prepared from polyethylene oxide with molecular weight of 600,000 (PEO_600K) and c-PEG_1K showed conductivity enhancement especially at low Li salt concentration.     

Ambient imaging mass spectrometry by electrospray ionization using solid needle as sampling probe

Although being an atmospheric pressure ion source, electrospray ionization (ESI) has rarely been used directly for ambient imaging mass spectrometry because the sample has to be introduced as liquid solution through the capillary. Instead of capillary, probe electrospray ionization (PESI), which has been developed recently, uses a solid needle as the sampling probe, as well as the electrospray emitter, and has been applied not only for liquid solutions but also for the direct sampling on wet samples. Biological tissues are composed of cells that contain 70–90% water, and when the surface is probed by the needle tip, the biological fluid adhering to the needle can be electrosprayed directly or assisted by additional solvent added onto the needle surface. Here, we demonstrate ambient imaging mass spectrometry of mouse brain section using PESI, incorporated with an auxiliary heated capillary sprayer. The solvent vapor generated from the sprayer condensed on the needle tip, re‐dissolving the adhered sample, and at the same time, providing an indirect means for needle cleaning. The histological sections were prepared by fixation using paraformaldehyde, and the spatial analysis was automated by maintaining an equal sampling depth into the sample in addition to raster scan. Phospholipids and galactosylceramides were readily detected from the mouse brain section in the positive ion mode, and were mapped with 60 µm lateral resolution to form mass spectrometric images. Copyright © 2009 John Wiley & Sons, Ltd.     

Active layer of the cathode of a fuel cell with a solid polymer electrolyte: The effect of the Nafion concentration on the overall characteristics

A computer-aided simulation of the structure of the active layer of the cathode of a fuel cell with a solid polymer electrolyte (Nafion) is performed under the assumption about equidimensionalness of dimensions of grains of the substrate (with platinum crystallites in them) and grains (agglomerates of molecules) of Nafion. It is analyzed how the Nafion concentration affects principal parameters, which include the specific surface area, in the vicinity of which electrochemical process goes on; the effective ionic electroconductivity, and the effective diffusion coefficient of a gas. It is demonstrated how one can determine the Nafion concentration at which the overall current takes on a maximum value. Dependences of the optimum value of the overall current and the thickness of the active layer and the weight of platinum, which correspond to it, on the Nafion concentration are calculated. It is demonstrated that there in principle cannot exist one individual optimum concentration of Nafion, which is suitable for all techniques used for the preparation of the active layer. The mutual relationship between values of the effective diffusion coefficient of a gas and the effective ionic electroconductivity of Nafion determines the value of the optimum of the Nafion concentration.     

Sol-gel synthesis and characterization of LiNO3-Al2O3 composite solid electrolyte

Composite solid electrolytes in the system (1 − x)LiNO₃-xAl₂O₃, with x = 0.0-0.5 were synthesized by sol-gel method. The synthesis carried out at low temperature resulted in voluminous and fluffy products. The obtained materials were characterized by X-ray diffraction, differential scanning calorimetry, scanning electron microscopy/energy dispersive X-ray, Fourier transform infrared spectroscopy and AC impedance spectroscopy. Structural analysis of the samples showed base centred cell type of point lattice of LiNO₃ for the composite samples with x = 0.1-0.2 and body centred cell for the sample with x = 0.3. A trace amount of α-LiAlO₂ crystal phase was also present in these composite samples. The thermal analysis showed that the samples were in a stable phase between 48 °C and 230-260 °C. Morphological analysis indicated the presence of amorphous phase and particles with sizes ranging from micro to nanometre scale for the composite sample with x = 0.1. The conductivities of the composites were in the order of 10⁻³ and 10⁻² S cm⁻¹ at room temperature and 150 °C, respectively.     

Mass transfer in porous systems, flooded in part with water, of gas diffusion and catalytic layers of the cathode of a fuel cell with a solid polymer electrolyte

Mass transfer in porous gas diffusion and catalytic layers of the cathode of a hydrogen-air fuel cell with a solid polymer electrolyte is considered. The transport processes are considered with allowance made for the partial flooding of porous systems of these layers with water, which forms during the fuel cell operation. The consideration also allows for the influence of the diluent gas present when air oxygen is used as the oxidant. The fraction of water-flooded pores is calculated within percolation theory as a function of structural parameters of the porous system. Conditions leading to the beginning of the gas diffusion layer flooding are presented.     

Low temperature preparation and fuel cell properties of rare earth doped barium cerate solid electrolytes

The solid electrolytes, BaCe_(0.8) Ln_(0.2)O_(2.9) (Ln: Gd, Sm, Eu), were prepared by the sol-gel method. XRD indicated that a pure orthorhombic phase was formed at 900℃. The synthesis temperature by the sol-gel method was about 600℃ lower than the high temperature solid phase reaction method, The electrical conductivity and impedance spectra were measured and the conduction mechanism was studied. The grain-boundary resistance of the solid electrolyte could be reduced or eliminated by the sol-gel method. The conductivity of BaCe_(0.8)Gd_(0.2)O_(2.9) is 7.87×10~(-2) S·cm~(-1) at 800℃. The open-circuit voltage of hydrogen-oxygen fuel cell using BaCe_(0.8) Gd_(0.2)O_(2.9) as electrolyte was near to 1 V and its maximum power density was 30 mW·cm~(-2).     

Cathode of a fuel cell with a solid polymer electrolyte: Calculating overall currents in the presence of a gas-diffusion layer

Mathematical apparatus, which makes it possible to perform calculations of the current-voltage characteristics of cathodes of fuel cells with a solid polymer electrolyte in conditions where there are present extraneous diffusion restrictions is proposed. In so doing, the partial pressure of oxygen and the absolute pressure of gas in the gas chamber may assume any values. First of all presented are the results of calculations of the current-voltage characteristics intrinsic to active layers of the air and oxygen cathodes, which are performed under the assumption that the extraneous diffusion restrictions are absent altogether. Thereafter, in the same conditions (at the same parameters that characterize the active layer of a cathode), obtained are results of a calculation of the current-voltage characteristics inherent in the air and oxygen cathodes in the presence of extraneous diffusion restrictions. Afterward there is performed an analysis of the way a gas-diffusion layer restricts the process of generation of current in a cathode and of what measures should be taken in order for the extraneous diffusion restrictions to become less significant.     

Discrimination and characterization of the volatile organic compounds of Acori tatarinowii rhizoma based on headspace-gas chromatography-ion mobility spectrometry and headspace solid phase microextraction-gas chromatography-mass spectrometry

Acori tatarinowii rhizome (ATR) is a Traditional Chinese Medicine (TCM), which has multiple effects, such as neuroprotective activity, antidepressant and other activity. However, the widespread cultivation of ATR has led to it varying quality. Therefore, it is important to find a method to quickly identify the components of ATR. Headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) and headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC–MS) were applied to analyze and characterize the volatile organic compounds (VOCs) of ATR. 33 VOCs were identified by HS-GC-IMS and 95 VOCs were identified by HS-SPME-GC–MS from 15 batches of ATR. Then, quantification of estragole, methyleugenol, γ-asarone, β-asarone and asarone by gas chromatography-mass spectrometry (GC–MS). The fingerprint of HS-GC-IMS and the heatmap of HS-SPME-GC–MS were established. Which compared differential components of ATR. In addition, principal component analysis (PCA) was performed on the results of both instruments. The VOCs in the ATR were significantly correlated with β-asarone and asarone by PatternHunter analysis. It assisted HS-GC-IMS determine ATR quality. It is the first report regarding the method development of HS-GC-IMS and HS-SPME-GC–MS that targets the VOCs characterization of ATR, and the findings obtained would benefit the quality control and distinguish the complex analytical objects of ATR.     

Hydrogen-oxygen (air) fuel cell with nafion and platinum: Calculating overall characteristics,comparing the performance of a cathode with polymeric electrolyte with a hydrophobized cathode with liquid electrolyte

Results of calculating the major overall characteristics of both an individual cathode and the whole hydrogen-oxygen (air) fuel cell with Nafion and platinum are shown. The effect of varying the parameters of both the active layer and the polymeric-electrolyte membrane on the overall characteristics of such a fuel cell is analyzed. The mechanisms of operation of active layers of hydrophobized cathodes and cathodes containing Nafion are compared. These two electrode types demonstrate a qualitative difference in the current generation mechanisms. As a result, the current in cathodes with Nafion increases more actively with the increase in over-potential (in proportion with exp [η₀/2], where η₀ is the cathodic overpotential) as compared with the case of hydrophobized cathodes (here the current ～ exp[η₀/4]). This explains the fact that a fuel cell with Nafion demonstrates so high power characteristics as compared with a fuel cell with hydrophobized electrodes and liquid electrolyte.     

Determination of flunitrazepam and 7-aminoflunitrazepam in human urine by on-line solid phase extraction liquid chromatography-electrospray-tandem mass spectrometry

A method using an on-line solid phase extraction (SPE) and liquid chromatography with electrospray-tandem mass spectrometry (LC-ES-MS/MS) for the determination of flunitrazepam (FM2) and 7-aminoflunitrazepam (7-aminoFM2) in urine was developed. A mixed mode Oasis HLB SPE cartridge column was utilized for on-line extraction. A reversed phase C₁₈ LC column was employed for LC separation and MS/MS was used for detection. Sample extraction, clean-up and elution were performed automatically and controlled by a six-port valve. Recoveries ranging from 94.8 to 101.3% were measured. For both 7-aminoFM2 and FM2, dual linear ranges were determined from 20 to 200 and 200-2000 ng/ml, respectively. The detection limit for each analyte based on a signal-to-noise ratio of 3 ranged from 1 to 3 ng/ml. The intra-day and inter-day precision showed coefficients of variance (CV) ranging from 4.6 to 8.5 and 2.6-9.2%, respectively. The applicability of this newly developed method was examined by analyzing several urine samples.