High-performance polymer ionomer–ionic liquid membrane IPMC actuator

A high-performance ionic polymer–metal composite (IPMC) actuator based on a polyelectrolyte membrane has been constructed from a poly((t-butyl-styrene)-b-(ethylene-r-propylene)-b-(styrene-r-styrene sulfonate)-b-(ethylene-r-propylene)-b-(t-butyl-styrene)) (tBS-EP-SS-EP-tBS; SSPB) pentablock copolymer ionomer and the ionic liquid (IL) 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMImTFSI). The SSPB copolymer ionomer had microphase-separated morphology comprising alternating styrene-rich ionic channel regions and aliphatic EP-rich non-ionic regions, on the several tens of nanometers scale (average diameter of ionic channel regions ca. 20 nm), whereas the most commonly used Nafion contained narrow ion clusters of less than 4 nm. The large ionic channels of SSPB enabled better transport of such bulky ions as IL ions, and endowed the SSPB–BMImTFSI membrane with ionic conductivity superior to that of the Nafion–BMImTFSI membrane (SSPB–BMImTFSI: 1.01 × 10^?4 S/cm, Nafion–BMImTFSI: 0.49 × 10^?4 S/cm). The SSPB–BMImTFSI membrane-based IPMC actuator generated a larger and faster electromechanical response than the Nafion-based IPMC.     

Effect of cobalt on the activity of dual phase “(Gd0.6Sr0.4)0.99Fe1-xCoxO3-δ” SOFC cathodes

Journal of Solid State Electrochemistry - The effect of the amount of cobalt in (Gd0.6Sr0.4)0.99Fe1-xCoxO3-δ solid oxide fuel cell (SOFC) cathodes (x = 0.00, 0.05, 0.10, 0.15, 0.20...     

Pressure–voltage oscillations as a diagnostic tool for PEFC cathodes

In this work, pressure-induced voltage oscillations are explored as a novel diagnostic tool for PEFC cathodes. In this method, a small signal oscillation is imposed on the cathode outlet pressure. As a response to this pressure perturbation, the fuel cell voltage exhibits oscillations with the same frequency. The amplitude ratio and phase difference between the voltage and pressure oscillations embody diagnostic information about the operating conditions and processes in the PEFC cathode.     

Effects of cobalt carbide on Fischer–Tropsch synthesis with MnO supported Co-based catalysts

Cobalt carbide(Co_2C)was considered as potential catalysts available for large-scale industrialization of transforming syngas(H_2 and CO)to clean fuels.Herein,we successfully synthesized Co-based catalysts with MnO supported,to comprehend the effects of Co_2C for Fischer–Tropsch synthesis(FTS)under ambient conditions.The huge variety of product selectivity which was contained by different active sites(Co and Co_2C)has been found.Furthermore,density functional theory(DFT)shows that Co_2C is efficacious of CO adsorption,whereas is weaker for H adsorption than Co.Combining the advantages of Co and Co_2C,the catalyst herein can not only obtain more C_(5+)products but also suppress methane selectivity.It can be a commendable guide for the design of industrial application products in FTS.     

Structural Arrangement of Fe–Sb–O Catalysts

In iron–antimony catalysts containing excess antimony oxide and consisting of a mixture of FeSbO₄ and -Sb₂O₄ phases, the structure of iron antimonate changes compared to the catalyst with an equimolar composition, which is the pure FeSbO₄ phase. In the presence of excess antimony oxide in the near-surface layer of iron antimonate, extended defects with a structure of crystallographic shift are formed. These accumulate overstoichiometric antimony. Such a structural change is associated with changes in the acid–base properties and the surface oxygen binding strength.     

High-performance three-dimensional flower-like CoS/MWCNT composite host for Li–S batteries

Journal of Solid State Electrochemistry - Although lithium–sulfur batteries are promising replacements for conventional lithium-ion batteries, their commercial applications have been limited...     

Sintering studies on Ni–Cu–YSZ SOFC anode cermet processed by mechanical alloying

New 40 vol%[(Cu)–Ni]–YSZ cermet materials processed by mechanical alloying (MA) of the row powders are prepared. The powder compacts are sintered in air, hydrogen and inert (argon) atmospheres at a dilatometer and tubular furnace up to 1,350 °C. Sintering by activated surface concept (SAS) can anticipate and enhance the densification in such powders. Stepwise isothermal dilatometry (SID) sintering kinetics study is performed allowing determining kinetic parameters for Ni–YSZ and Ni–Cu–YSZ pellets. Two-steps sintering processes is indicated while Cu-bearing material features the smallest activation energy for sintering. The allied MA–SAS method is a promising route to prepare SOFC fuel cell anode materials.     

Determination of Caseinomacropeptide in Brazilian Bovine Milk by High-performance Liquid Chromatography–Mass Spectrometry

Milk adulteration is a concern in many countries, including Brazil. There are many compounds used as adulterants, including cheese whey, a by-product of cheese. Recently, we have developed a proteomic-like technique for separation and characterization of caseinomacropeptide using liquid chromatography coupled to mass spectrometry with electrospray ionization. Caseinomacropeptide is important because it can be used as marker when cheese whey adulteration is performed in bovine milk. Furthermore, it is difficult to establish reference values for caseinomacropeptide levels because of the variation of milk composition. The aim of this study was to verify the average value for caseinomacropeptide present in bovine raw milk collected by Federal Inspection Service from five regions of Brazil (north, northwest, west central, south, southeast). Survey sampling was divided into two stages: first one, a data set 1 (regional sampling) was collected only from the south during a year. This data sampling was used to estimate the data set 2 (national sampling). A largest extreme value was suggested as a model for caseinomacropeptide distributions for national sampling. The data set showed 2.52?mg?L^?1 as the mean and 4.80?mg?L^?1 for the standard deviation based on a sampling size of 170?units collected across Brazil. The findings are useful to understand the presence of caseinomacropeptide, especially when no adulteration or the absence of good practices is present.     

Determination of Aristocularine Enantiomers by Dispersive Liquid–Liquid Microextraction and Chiral High-performance Liquid Chromatography

Here is reported a novel analytical approach for the extractive separation and determination of enantiomeric ratios of aristocularine in bovine serum albumin. The results demonstrate suitable analytical performances. The separation was performed by chiral high-performance liquid chromatography with a 5-µm column using a mobile phase of 1:1 n-hexane:ethanol at a flow rate of 0.7?mL?min^?1 with ultraviolet–visible absorption, circular dichroism, and polarimetric detection. The enantiomers were eluted at 13.2 and 15.6?min for (+) and (?)-aristocularine, with a resolution of 1.58 and a separation factor of 1.27. The analytical parameters for the dispersive liquid–liquid microextraction were optimized; under these conditions, the extraction recoveries were from 88.6% to 93.9% for a two-step extraction. The precision, reported as the percent relative standard deviation, had values from 2.9% to 3.2% for 0.5?µg?mL^?1 of analyte for five replicate measurements using ultraviolet–visible absorption and circular dichroism detection. The limits of detection were between 0.05 and 0.08?µg?mL^?1 with enrichment ratios up to a value of 12.     

Recent developments in Ruddlesden–Popper nickelate systems for solid oxide fuel cell cathodes

Motivated by recent work on the Ruddlesden–Popper material, which was shown to be a superior oxide-ion conductor than conventional solid-oxide fuel cell cathode perovskite materials, we undertook A- and B-site doping studies of the Ruddlesden–Popper nickelate series in an attempt to identify other candidates for cathode application. In this paper, we summarize our most significant results for the and systems and more recently, the higher-order Ruddlesden–Popper phases La _n+1Ni _n O_3n+1 (n=2 and 3), which show greater promise as cathode materials than the n=1 compositions.     

Electrochemical and microgravimetric characterization of magnetron-sputtered Fe–Cr–Ni–Ta and Fe–Cr–Ni alloy films in neutral and strongly acidic media

The Fe–Cr–Ni and Fe–Cr–Ni–Ta alloy films were deposited on quartz substrates by magnetron-sputtering using targets of AISI 316 stainless steel and in combination with pure tantalum. The conventional melting of the Fe–Cr–Ni–Ta alloy formed is virtually impossible because the melting point of tantalum is higher than the boiling points of the other components. Elemental content of the films was determined by XPS analysis. Corrosion behaviour of both alloy films was studied in 5% NaCl and 10 M HCl by electrochemical quartz crystal microgravimetry (EQCM), electrochemical impedance spectroscopy (EIS) and dc-voltammetry. The corrosion resistance of Fe–Cr–Ni–Ta appeared to be significantly higher than that of Fe–Cr–Ni in both neutral (5% NaCl) and strongly acidic (10 M HCl) media. The Fe–Cr–Ni–Ta specimen exhibited an extremely high corrosion resistance in 10 M HCl, where the corrosion rates were about one order of magnitude lower than those of Fe–Cr–Ni in neutral solution. EQCM measurements in NaCl solution indicated accumulation of corrosion products on the Fe–Cr–Ni–Ta surface, which was evident from a distinctive increase in electrode mass. By contrast, the mass of the tantalum-free alloy film decreased with a constant rate, which indicated alloy dissolution to prevail. The corrosion current calculated from the mass decrease was in good agreement with that derived from voltammetric measurements. The EQCM data showed that the corrosion resistance of the Fe–Cr–Ni–Ta alloy film in 10 M HCl was about two orders of magnitude higher than that of the Fe–Cr–Ni.     

Electrochemical reactivity of Li–Mn–O and Li–Fe–Mn–O spinels

Electrochemical reductive dissolution of Li–Mn–O and Li–Fe–Mn–O spinels and Li⁺ extraction/insertion in these oxides were performed using voltammetry of microparticles. Both electrochemical reactions are sensitive to the Fe/(Fe+Mn) ratio, specific surface area, Li content in tetrahedral positions, and Mn valence, and can be used for electrochemical analysis of the homogeneity of the elemental and phase composition of synthetic samples. The peak potential (E _P) of the reductive dissolution of the Li–Mn–O spinel is directly proportional to the logarithm of the specific surface area. E _P of Li–Fe–Mn–O spinels is mainly controlled by the Fe/(Fe+Mn) ratio. Li⁺ insertion/extraction can be performed with Mn-rich Li–Fe–Mn–O spinels in aqueous solution under an ambient atmosphere and it is sensitive to the regularity of the spinel structure, in particularly to the amount of Li in tetrahedral positions and the Mn valence. Electronic Publication     

A novel design of single-chamber SOFC micro-stack operated in methane–oxygen mixture

In this paper, a novel design of single-chamber solid oxide fuel cell (SC-SOFC) micro-stack with star-shape was presented and operated successfully in methane–oxygen mixture. This stack consisted of four anode-supported single cells connected in series, and generated a maximum power output of 421 mW (total active area: 1 cm²) at the furnace temperature of 750 °C, which powered an USB fan stably. The symmetric design can ensure the identical operation of each cell, and good capacity for scale-up of the stack.     

Specific features of phase equilibriums in Ln–Ba–Fe–O systems

Formation of five-layered Ln_2–εBa_3+εFe₅O_15–δ phases [exhibiting nanoscale ordering with layer-by-layer location of the cations in the Ln–Ba–(Ln,Ba)–(Ln,Ba)–Ba–Ln perovskite-type structure] has occurred in the Ln–Ba–Fe–O (Ln = Y, Pr, Nd, Sm, Eu, and Gd) systems at 1100°С in air. Partial substitution of iron with cobalt (Ln_2–εBa_3+εFe_5–yCo_yO_15–δ, Ln = Nd, Sm, Eu) has stabilized formation of the ordered structure. The oxygen content in the complex oxides has been determined in air over a wide temperature range by means of high-temperature thermogravimetry and iodometric titration. The change in oxygen content with temperature for the phases with five-layered ordering was significantly smaller than for the disordered phases.     

Synthesis of quasi-crystalline phases in the Al–Cu–Fe–Cr system

Phase equilibria in the Al–Cu–Fe system alloyed with 5% Cr were studied. Based on the data of X-ray powder diffraction analysis, electron microscopy, and differential thermal analysis, the effect of temperature on i ? d phase transitions in alloys Al₆₅Cu₂₅Fe₅Cr₅ and Al₇₀Cu₂₀Fe₅Cr₅. In the Al–Cu–Fe–Cr system, multiphase structures were detected; these structures are mixtures of quasi-crystalline and approximant phases, the contents and morphologies of which depend on the composition of the initial mixture and the crystallization rate.     

High-performance liquid chromatographic determination of diltiazem in human plasma after solid-phase and liquid–liquid extraction

A selective, sensitive, and accurate high-performance liquid chromatographic method for determination of diltiazem in plasma samples has been developed and validated. The effects of mobile phase composition, buffer concentration, mobile phase pH, and concentration of organic modifiers on retention of diltiazem and internal standard were investigated. Solid-phase and liquid–liquid extraction were examined and proposed for isolation of the drug and elimination of endogenous plasma interferences. A 5 m Lichrocart Lichrospher 60 RP-select B chromatographic column was used; the mobile phase was acetonitrile–0.025 mol L^–1 KH₂PO₄ (pH 5.5), 35:65 ( v / v) at a flow-rate of 1.5 mL min^–1. The detection wavelength was 215 nm. The calibration plots were linear in the concentration range 20.0–500.0 ng mL^–1. The method has been implemented to monitor diltiazem levels in patient samples.     

Bayesian Optimization-guided Discovery of High-performance Methane Combustion Catalysts based on Multi-component PtPd@CeZrOx Core–Shell Nanospheres

Formula regulation of multi-component catalysts by manual search is undoubtedly a time-consuming task, which has severely impeded the development efficiency of high-performance catalysts. In this work, PtPd@CeZrO_x core–shell nanospheres, as a successful case study, is explicitly demonstrated how Bayesian optimization (BO) accelerates the discovery of methane combustion catalysts with the optimal formula ratio (the Pt/Pd mole ratio ranges from 1/2.33–1/9.09, and Ce/Zr from 1/0.22–1/0.35), which directly results in a lower conversion temperature (T₅₀ approaching to 330 °C) than ones reported hitherto. Consequently, the best sample obtained could be efficiently developed after two rounds of iterations, containing only 18 experiments in all that is far less than the common human workload via the traditional trial-and-error search for optimal compositions. Further, this BO-based machine learning strategy can be straightforward extended to serve the autonomous discovery in multi-component material systems, for other desired properties, showing promising opportunities to practical applications in future.     

Chromium poisoning and degradation at LaNi0.6Fe0.4O3 cathode with LaNi0.6Fe0.4O3–Gd0.2Ce0.8O2 functional layer for SOFC under open circuit condition

Journal of Solid State Electrochemistry - We fabricate symmetrical cells adopting LaNi0.6Fe0.4O3–δ (LNF) cathode with LNF–Gd0.2Ce0.8O2 (GDC) functional layer on scandia-stabilized...     

Evaluation of stability of silica-supported Fe–Pd and Fe–Pt nanoparticles in aerobic conditions using thermal analysis

The applications of zerovalent iron nanoparticles (nZVI) exploit their high reactivity which decreases due to oxidation in aerobic conditions during manufacture, application, and storage. In this study, we present the new procedure for estimation of the nZVI stability to oxidation in air. The procedure is suitable for characterization of the novel materials based on the supported nZVI. Nanoscale particles were synthesized inside porous silica supports by incipient wetness impregnation with the metal precursor solutions followed by thermal treatment. The TG–DTA studies revealed the decomposition temperature of the supported precursors, as well as the interaction of Fe and precious metal precursors, which resulted in the formation of alloy nanoparticles. Characterization of the samples by XRD confirmed the formation of the nanoparticles of the metallic Pd, Pt, and Fe phases supported on SiO₂ carriers, as well as the formation of solid solutions based on the structure of precious metals. The new procedure for estimation of the nZVI stability included (1) TPR with hydrogen up to 400–425 °C followed by isothermal reduction at these temperatures; (2) in situ reoxidation with oxygen at room temperature. The samples were reduced “as obtained” and after in situ reoxidation. The results of the TPR studies exhibited that introduction of both Pd and Pt protected the Fe nanoparticles from oxidation with oxygen and air at ambient conditions.