Optimization on fabrication and performance of A-site-deficient La0.58Sr0.4Co0.2Fe0.8O3-δ cathode for SOFC

A-site-deficient perovskite cathode material La_0.58Sr_0.4Co_0.2Fe_0.8O_3 − δ (L58SCF) is coated on the yttria-stabilized zirconia electrolyte by screen-printing technique. Several key fabrication parameters including selection of additives (binder and pore former), effect of coating thickness, sintering temperature and time on the microstructure, and electrochemical performance of cathode are investigated by scanning electron microscopy and electrochemical impedance spectroscopy. We study the microstructure and the electrochemical property of the cathode with different kinds of additives. Results show that the cathode possesses fine microstructure, enough porosity, and ideal electrochemical property when polyvinyl butyral serves as both binder and pore former in the cathode. The cathode with three screen-printing coats (thickness 28 ± 7 μm, weight 6.07 ± 0.72 mg cm⁻²) sintering at 1,000 °C for 2 h shows lower polarization resistance of 0.183 Ω cm² at 800 °C. Based on the optimized parameters, the polarization resistances of the L58SCF–Ce_0.8Gd_0.2O_{1.9 – δ} composite cathode display the R _p values of 0.067 Ω cm² at 800 °C, 0.106 Ω cm² at 750 °C, 0.225 Ω cm² at 700 °C, and 0.550 Ω cm² at 650 °C.     

Electrochemical cell with solid oxide electrolyte and oxygen pump thereof

The paper presents the scientific basis and technical implementation of a method for obtaining oxygen by extraction from air using an electrochemical cell based on a solid oxide cell (SOC) with anion-conducting solid electrolyte. A nanopowder of a weak aggregate of the YSZ solid electrolyte and LSM fine powder was used to manufacture SOC. The electrolyte-electrode SOC structure was formed as a tube by joint pressing of functional layers and the further co-sintering at the temperature of 1200°C. The characteristics of an electrochemical cell of the oxygen pump based on a thin-wall tube of the YSZ supporting electrolyte (150 μm) with symmetrical electrodes based on LSM (∼20 μm) are studied. A prototype of a compact oxygen generator (oxygen pump) is developed and manufactured with an electrochemical part based on three serially connected SOCs. The connection is implemented in the form of metallic couplings of the Crofer 22 APU steel. The method of reaction magnetron sputtering was used to protect current leads from corrosion by applying a coating based on a Mn _x Co_{3 − x} O₄ spinel. The efficiency of a demonstration prototype at 800°C was 9 l/h at the power consumption of 50 W. The current density through SOC was 1.1 A/cm². The prototype was designed to contain no noble metal components. It is shown that the engineering approach applied allows manufacturing effective nanostructural SOCs and devices on their basis.     

Reversible Solid–Solid Conversion of Sulfurized Polyacrylonitrile Cathodes in Lithium–Sulfur Batteries by Weakly Solvating Ether Electrolytes

Despite carbonate electrolytes exhibiting good stability to sulfurized polyacrylonitrile (SPAN), their chemical incompatibility with lithium (Li) metal anode leads to poor electrochemical performance of Li||SPAN full cells. While the SPAN employs conventional ether electrolytes that suffer from the shuttle effect, leading to rapid capacity fading. Here, we tailor a dilute electrolyte based on a low solvating power ether solvent that is both compatible with SPAN and Li metal. Unlike conventional ether electrolytes, the weakly solvating ether electrolyte enables SPAN to undergo reversibly “solid–solid” conversion. It features an anion–rich solvation structure that allows for the formation of a robust cathode electrolyte interphase on the SPAN, effectively blocking the dissolution of polysulfides into the bulk electrolyte and avoiding the shuttle effect. What's more, the unique electrolyte chemistry endowed Li ions with fast electroplating kinetics and induced high reversibility Li deposition/stripping process from 25 °C to −40 °C. Based on tailored electrolyte, Li||SPAN full cells matched with high loading SPAN cathodes (≈3.6 mAh cm⁻²) and 50 μm Li foil can operate stably over a wide range of temperatures. Additionally, Li||SPAN pouch cell under lean electrolyte and 5 % excess Li conditions can continuously operate stably for over a month.     

Crystallographic and theoretical studies of 4,4′-dimethyl-7,7′-bi([1,2,5]thiadiazolo[3,4-b]pyridylidene)–chloranilic acid (1/1) with intermolecular O–H···N hydrogen bonds and S···O heteroatom interactions

Abstract  The molecular and crystal structure of a 1:1 co-crystal of 4,4′-dimethyl-7,7′-bi([1,2,5]thiadiazolo[3,4-b]pyridylidene)–chloranilic acid, (1), has been determined by X-ray diffraction at the monoclinic space group P2₁/c with cell parameters of a = 8.422(6), b = 7.343(4), c = 16.112(7) ?, β = 104.988(8)°, V = 962.5(10) ?³ and Z = 2. In the crystal structure, two components connect via the intermolecular O–H···N hydrogen bonds [2.804(4) ?] and S···O heteroatom interaction [2.945(3) ?] with R ₂ ²(7) couplings to form a unique and infinite one-dimensional supramolecular tape structure. The calculations of (1) at the HF/6-31G(d), MP2/6-31G(d), and B3LYP/6-31G(d) levels can almost reproduce X-ray geometry. In addition, the distances of the intermolecular O–H···N and S···O interactions by MP2/6-31G(d) and B3LYP/6-31G(d) levels agree well with those in the crystal. The calculated binding energies corrected BSSE and ZPE are −4.487 (HF), −7.473 (MP2), and −5.640 (B3LYP) kcal/mol. The results suggest that the complex (1) is very stable and the dispersion interaction is significantly important for the attractive intermolecular interaction in (1). The NBO analysis has revealed that the n(N) → σ*(O–H) interaction gives the strongest stabilization to the system and the major interaction for the intermolecular S···O contact is n(O) → σ*(S–N). Index Abstract  In the crystal structure of the title compound, the molecules are linked by intermolecular O–H···N hydrogen bonds and short S···O heteroatom interactions with R ₂ ²(7) couplings to construct a unique and infinite one-dimensional supramolecular tape structure.      

Electrochemical synthesis of ammonia using a cell with a Nafion membrane and SmFe0.7Cu0.3?xNixO3 (x = 0?0.3) cathode at atmospheric pressure and lower temperature

Samaria-doped ceria Ce_0.8Sm_0.2O_2−δ (SDC) and SmFe_0.7Cu_0.3−x Ni _x O₃ have been synthesized by the sol-gel method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The electrochemical synthesis of ammonia was investigated at atmospheric pressure and low temperature, using the SFCN materials as the cathode, a Nafion membrane as the electrolyte, nickel-doped SDC (Ni-SDC) as the anode and silver-platinum paste as the current collector. Ammonia was synthesized from 25 to 100°C when the SFCN materials were used as cathode, with SmFe_0.7Cu_0.1Ni_0.2O₃ giving the highest rates of ammonia formation. The maximum rate of evolution of ammonia was 1.13 × 10⁻⁸ mol·cm⁻²·s⁻¹ at 80°C, and the current efficiency reached as high as 90.4%. Supported by the National Natural Science Foundation of China (Grant No. 20863007)     

A synthetic iron phosphate mineral, spheniscidite, [NH4]+[Fe2(OH)(H2O)(PO4)2]?H2O, exhibiting reversible dehydration

Spheniscidite, a synthetic iron phosphate mineral has been synthesized by hydrothermal methods. The material is isotypic with another iron phosphate mineral, leucophosphite. Spheniscidite crystallizes in the monoclinic spacegroupP2₁/n. (a=9·845(1),b=9·771(3),c=9·897(1),β=102·9°,V=928·5(1),Z=4,M=372·2,d _calc=2·02 g cm⁻³ andR=0·02). The structure consists of a network of FeO₆ octahedra vertex-linked with PO₄ tetrahedra forming 8-membered one-dimensional channels in which the NH₄ ⁺ ions and H₂O molecules are located. The material exhibits reversible dehydration and good adsorption behaviour. Magnetic susceptibility measurements indicate that the solid orders antiferromagnetically.     

Electrochemical modification of Bi2S3 coatings in a nickel plating electrolyte

The electrochemical behavior of Bi₂S₃ coatings in Watts nickel plating electrolyte was investigated using the cyclic voltammetry, electrochemical quartz crystal microbalance, X-ray diffraction, and energy dispersive X-ray analysis methods. During the bismuth sulfide coating reduction in Watts background electrolyte in the potential region from −0.4 to −0.6 V, the Bi₂S₃ and Bi(III) oxygen compounds are reduced to metallic Bi, and the decrease in coating mass is related to the transfer of S²⁻ ions from the electrode surface. When the bismuth sulfide coating is reduced in Watts nickel plating electrolyte, the observed increase in coating mass in the potential region −0.1 to −0.4 V is conditioned by Ni²⁺ ions reduction before the bulk deposition of Ni, initiated by Bi₂S₃. In this potential region, the reduction of Bi(III) oxygen compounds can occur. After the treatment of as-deposited bismuth sulfide coating in nickel plating electrolyte at E = −0.3 V, the sheet resistance of the layer decreases from 10¹³ to 500–700 Ω cm. A metal-rich mixed sulfide Ni₃Bi₂S₂–parkerite is obtained when as-deposited bismuth sulfide coating is treated in Watts nickel plating electrolyte at a potential close to the equilibrium potential of the Ni/Ni²⁺ system and then annealed at temperatures higher than 120 °C.     

The effect of electrolyte on the micellar properties of an anionic-nonionic detergent in aqueous solution

Summary The effect of sodium chloride on the micellar properties of an anionic-nonionic detergent C₁₆H₃₃(OCH₂·CH₂)₇OSO₃Na has been investigated and the results have been compared with previous measurements on the nonionic analogue C₁₆H₃₃(OCH₂·CH₂)₇OH. Light scattering and viscosity measurements showed that, over the electrolyte concentration range studied (0–1.0M NaCl), the micelles were very much smaller (m.m.w.=74,800 in 0.1M NaCl) than those of the nonionie analogue and exhibited no similar variation of size, shape or hydration with temperature, indicating that addition of electrolyte caused insufficient shielding of the micellar charge to induce nonionic behaviour. Viscosity results suggested a reduction in the micellar hydration with increase in electrolyte concentration to a limiting value of 0.28 g H₂O/g of detergent for salt concentrations greater than 0.01M. A possible explanation of this effect is proposed. The effect of electrolyte on the c.m.c. was determined from surface tension measurements and was described by the equation, log c.m.c.=−6.4−0.54 log (c.m.c.+salt conc.) Comparison with data reported for sodium hexadecylpolyoxyethylene sulphates with shorter ethylene oxide chain lengths indicated a decrease in the c.m.c. in salt-free systems with increase in the chain length, the data obeying the equation, log c.m.c.=−3.5−0.20n wheren is the number of ethylene oxide groups in the chain.     

Electrochemical Study on Reactive Red 15 and its Interaction with Cyclodextrins

In this paper, the electrochemical behavior of the interaction of Reactive Brilliant Red K-2G (C.I. Reactive Red 15) with cyclodextrins in 0.1 mol · l⁻¹ NaCl (pH 6.9) has been studied by polarography and voltammetry. In a supporting electrolyte of NaCl (pH 6.9), a sensitive second derivative reduction peak (i _p ″) of Reactive Red 15 was found by linear sweep voltammetry (LSV). The peak potential is about −0.78 V (versus SCE). On the addition of CDs into the Reactive Red 15 solution, the reduction peak current (i _p ″) of Reactive Red 15 decreases and the peak potential (E _p ) shifts to a more positive potential. The study shows that Reactive Red 15 can form 1:1 inclusion complexes with nine CDs. The inclusion constants were calculated by “electric current method”. Furthermore, the inclusion ability of different kinds of cyclodextrins was compared, which provided some elemental data for application of Reactive Red 15 and cyclodextrins.     

Mechanistic aspects of the substrate ionization step in aminium salt catalyzed cyclopropanation

The cyclopropanations of a series of m- and p-substituted trans-β-methylstyrenes (3) by ethyl diazoacetate (4), catalyzed by tris(4-bromophenyl)aminium hexachloroantimonate (1 ^·+) and also by tris(2,4-dibromphenyl) aminium hexachloroantimonate (2 ^·+) have been studied by competition kinetics. For the reactions catalyzed by the milder aminium salt (1 ^·+), the Hammett-Brown ρ values and the fact that the absolute rates are independent of the concentration of 4 establish that ionization to 3 ^·+ is not reversible, but rate-determining. The dependence of the magnitude of ρ upon the absolute concentration of 3 indicates the operation of competing chain and catalytic mechanisms, i.e. the ionization of 3 by both product cation radicals and by the catalyst. The extremely low ρ value observed in the reactions catalyzed by 2 ^·+ indicates the exclusive operation of a relatively unselective chain mechanism. These mechanistic assignments are further supported by the observation of the formation of the same products under electrochemical conditions, in the absence of a chemical catalyst, in closely comparable diastereoisomer ratios and with ρ values which correspond nicely with the ρ values observed for equipotential aminium salt catalysts.     

Thermochemical study on ternary complex of dysprosium <Emphasis Type="Italic">m</Emphasis>-nitrobenzoic acid with <Emphasis Type="Italic">o</Emphasis>-phenanthroline

A ternary binuclear complex of dysprosium chloride hexahydrate with m-nitrobenzoic acid and 1,10-phenanthroline, [Dy(m-NBA)₃phen]₂·4H₂O (m-NBA: m-nitrobenzoate; phen: 1,10-phenanthroline) was synthesized. The dissolution enthalpies of [2phen·H₂O(s)], [6m-HNBA(s)], [2DyCl₃·6H₂O(s)], and [Dy(m-NBA)₃phen]₂·4H₂O(s) in the calorimetric solvent (V_DMSO:V_MeOH = 3:2) were determined by the solution–reaction isoperibol calorimeter at 298.15 K to be \Updelta_\texts H_\textm^q \Updelta_{\text{s}} H_{\text{m}}^{\theta } [2phen·H₂O(s), 298.15 K] = 21.7367 ± 0.3150 kJ·mol⁻¹, \Updelta_\texts H_\textm^q \Updelta_{\text{s}} H_{\text{m}}^{\theta } [6m-HNBA(s), 298.15 K] = 15.3635 ± 0.2235 kJ·mol⁻¹, \Updelta_\texts H_\textm^q \Updelta_{\text{s}} H_{\text{m}}^{\theta } [2DyCl₃·6H₂O(s), 298.15 K] = −203.5331 ± 0.2200 kJ·mol⁻¹, and \Updelta_\texts H_\textm^q \Updelta_{\text{s}} H_{\text{m}}^{\theta } [[Dy(m-NBA)₃phen]₂·4H₂O(s), 298.15 K] = 53.5965 ± 0.2367 kJ·mol⁻¹, respectively. The enthalpy change of the reaction was determined to be \Updelta_\textr H_\textm^q = 3 6 9. 4 9 ±0. 5 6   \textkJ·\textmol ^{- 1} . \Updelta_{\text{r}} H_{\text{m}}^{\theta } = 3 6 9. 4 9 \pm 0. 5 6 \;{\text{kJ}}\cdot {\text{mol}}^{ - 1} . According to the above results and the relevant data in the literature, through Hess’ law, the standard molar enthalpy of formation of [Dy(m-NBA)₃phen]₂·4H₂O(s) was estimated to be \Updelta_\textf H_\textm^q \Updelta_{\text{f}} H_{\text{m}}^{\theta } [[Dy(m-NBA)₃phen]₂·4H₂O(s), 298.15 K] = −5525 ± 6 kJ·mol⁻¹.     

AFM study of morphological changes associated with electrochemical solid–solid transformation of three-dimensional crystals of TCNQ to metal derivatives (metal = Cu, Co, Ni; TCNQ = tetracyanoquinodimethane)

In situ atomic force microscopy (AFM) allows images from the upper face and sides of TCNQ crystals to be monitored during the course of the electrochemical solid–solid state conversion of 50 × 50 μm² three-dimensional drop cast crystals of TCNQ to CuTCNQ or M[TCNQ]₂(H₂O)₂ (M = Co, Ni). Ex situ images obtained by scanning electron microscopy (SEM) also allow the bottom face of the TCNQ crystals, in contact with the indium tin oxide or gold electrode surface and aqueous metal electrolyte solution, to be examined. Results show that by carefully controlling the reaction conditions, nearly mono-dispersed, rod-like phase I CuTCNQ or M[TCNQ]₂(H₂O)₂ can be achieved on all faces. However, CuTCNQ has two different phases, and the transformation of rod-like phase 1 to rhombic-like phase 2 achieved under conditions of cyclic voltammetry was monitored in situ by AFM. The similarity of in situ AFM results with ex situ SEM studies accomplished previously implies that the morphology of the samples remains unchanged when the solvent environment is removed. In the process of crystal transformation, the triple phase solid∣electrode∣electrolyte junction is confirmed to be the initial nucleation site. Raman spectra and AFM images suggest that 100% interconversion is not always achieved, even after extended electrolysis of large 50 × 50 μm² TCNQ crystals.     

Combined DFT with NBO and QTAIM studies on the hydrogen bonds in (CH<Subscript>3</Subscript>OH)<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript> (<Emphasis Type="Italic">n</Emphasis> = 2–8) clusters

The (CH₃OH) _n (n = 2–8) clusters formed via hydrogen bond (H-bonds) interactions have been studied systemically by density functional theory (DFT). The relevant geometries, energies, and IR characteristics of the intermolecular OH···O H-bonds have been investigated. The quantum theory of atoms in molecule (QTAIM) and natural bond orbital (NBO) analysis have also been applied to understand the nature of the hydrogen bonding interactions in clusters. The results show that both the strength of H-bonds and the deformation are important factors for the stability of (CH₃OH) _n clusters. The weakest H-bond was found in the dimer. The strengths of H-bonds in clusters increase from n = 2 to 8, moreover, the strengths of H-bonds in (CH₃OH) _n (n = 4–8) clusters are remarkably stronger than those in (CH₃OH) _n (n = 2, 3) clusters. The small differences of the strengths of H-bonds among (CH₃OH) _n (n = 6–8) clusters indicate that a partial covalent character is attributed to the H-bonds in these clusters. The linear relationships between the electron density of BCP (ρ_b) and the H···O bond length of H-bonds as well as the second-perturbation energies E(2) have also been investigated and used to study the nature of H-bonds, respectively.     

Crystal Structures of Na3PO2S2 · 11H2O and Na3POS3 · 11H2O

Summary.  Single crystals of sodium dithiophosphate undecahydrate (Na₃PO₂S₂ · 11H₂O) and sodium trithiophosphate undecahydrate (Na₃POS₃ · 11H₂O) were grown from aqueous solution. The crystal structures of Na₃PO₂S₂ · 11H₂O (P2₁2₁2₁; a = 1248.1(1), b = 945.2(1), c = 1383.1(1) pm; R ₁ = 0.0202, wR ₂ = 0.0502) and Na₃POS₃ · 11H₂O (Pna2₁; a = 1262.0(2), b = 947.6(2), c = 1431.5(2) pm; R ₁ = 0.0720, wR ₂ = 0.1371) are related to each other in a sense that all constituting units are arranged in similar positions and with similar orientations. The geometries of the anions were determined with high accuracy; thus, the structural parameters of the POS³⁻ ₃ anion were measured for the first time. Received September 25, 2001. Accepted January 21, 2002     

Synthesis,spectroscopic, thermal and biological aspect of mixed ligand copper(II) complexes

Derivative of 8-hydroxyquinoline i.e. Clioquinol is well known for its antibiotic properties, drug design and coordinating ability towards metal ion such as Copper(II). The structure of mixed ligand complexes has been investigated using spectral, elemental and thermal analysis. In vitro anti microbial activity against four bacterial species were performed i.e. Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens, Bacillus substilis and found that synthesized complexes (15–37 mm) were found to be significant potent compared to standard drugs (clioquinol i.e. 10–26 mm), parental ligands and metal salts employed for complexation. The kinetic parameters such as order of reaction (n = 0.96–1.49), and the energy of activation (E _a = 3.065–142.9 kJ mol⁻¹), have been calculated using Freeman–Carroll method. The range found for the pre-exponential factor (A), the activation entropy (S* = −91.03 to−102.6 JK⁻¹ mol⁻¹), the activation enthalpy (H* = 0.380–135.15 kJ mol⁻¹), and the free energy (G* = 33.52–222.4 kJ mol⁻¹) of activation reveals that the complexes are more stable. Order of stability of complexes were found to be [Cu(A⁴)(CQ)OH] · 4H₂O > [Cu(A³)(CQ)OH] · 5H₂O > [Cu(A¹)(CQ)OH] · H₂O > [Cu(A²)(CQ)OH] · 3H₂O     

Synthesis and properties of nanosized tin-zinc composite oxides as lithium storage materials

After preparing the precursor by a liquid precipitation method, a series of tin-zinc composite oxides with different components and structures were synthesized as the anode materials for lithium ion batteries when the precursor was pyrolyzed at different temperatures. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and electrochemical measurements. The reversible capacity of amorphous ZnSnO₃ is 844 mA · h/g in the first cycle and the charge capacity is 695 mA · h/g in the tenth cycle. The reversible capacity of ZnO · SnO₂ is 845 mA · h/g in the first cycle and the charge capacity is 508 mA · h/g in the tenth cycle. The reversible capacity of SnO₂ · Zn₂SnO₄ is 758 mA · h/g in the first cycle and the charge capacity is 455 mA · h/g in the tenth cycle. Results show that amorphous ZnSnO₃ exhibits the best electrochemical property among all of the tin-zinc composite oxides. With the formation of crystallites in the samples, the electrochemical property of the tin-zinc composite oxides decreases. Translated from Chem J Chin Univ, 2006, 27(12): 2252–2255 [译自: 高等学校化学学报]     

Metal complexes of fenoterol drug

Metal complexes of fenoterol (FEN) drug are prepared and characterized based on elemental analyses, IR, ¹H NMR, magnetic moment, molar conductance, and thermal analyses (TG and DTA) techniques. From the elemental analyses data, the complexes are formed in 1:2 [Metal]:[FEN] ratio and they are proposed to have the general formula [Cu(FEN)₂]·2H₂O; [M(FEN)₂(H₂O)₂]·yH₂O (where M = Mn(II) (y = 2), Co(II) (y = 4), Ni(II) (y = 4), and Zn(II) (y = 0) and [Cr(FEN)₂(H₂O)₂]Cl·H₂O. The molar conductance data reveal that all the metal chelates are non-electrolytes except Cr(III) complex, having 1:1 electrolyte. IR spectra show that FEN is coordinated to the metal ions in a uninegative bidentate manner with ON donor sites of the aliphatic –OH and secondary amine –NH. From the magnetic moment measurements, it is found that the geometrical structures of these complexes are octahedral (Cr(III), Mn(II), Co(II), Ni(II), and Zn(II)) and square planar (Cu(II)). The thermal behavior of these chelates is studied using thermogravimetric and differential thermal analyses (TG and DTA) techniques. The results obtained show that the hydrated complexes lose water molecules of hydration followed immediately by decomposition of the coordinated water and ligand molecules in the successive unseparate steps. The FEN drug, in comparison to its metal complexes is also screened for their antibacterial activity against bacterial species (Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Salmonella typhi), Yeasts (Candida albicans and Saccharomyces cervisiae), and Fungi (Aspergillus niger and Aspergillus flavus). The activity data show that the metal complexes have antibacterial activity like that of the parent FEN drug against one or more species.     

Preparation, characterization, and application of electrodes modified with electropolymerized one-dimensional Magnus' green salts: Pt(NH3)4 · PtCl4 and Pt(NH3)4 · PtCl6

We report the modification of various electrode surfaces with electropolymerized Magnus' green salts, [Pt(NH₃)₄ · PtCl₄] _n and [Pt(NH₃)₄ · PtCl₆] _n . The modified electrodes were prepared by cyclic scanning of the electrode potential in an aqueous solution containing Pt(NH₃)₄ ²⁺ and PtCl₄ ²⁻ or PtCl₆ ²⁻ and the supporting electrolyte. The conditions for the film deposition were studied in detail. Several surface analytical techniques, including micro-Raman scattering and X-ray diffraction, were employed to characterize the modifier film. The electrochemical behavior of the modified electrode was studied in detail and the modified electrodes display very good electrocatalytic activity in the oxidation of ascorbic acid, hydrogen peroxide, thiosulfate, and especially nitric oxide. Received: 22 April 1999 / Accepted: 30 June 1999