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The electrochemical properties and stability during storage of pristine and AlPO4-coated LiCoO2 thin films were characterized. The wide and smooth surface of the thin film electrode might provide an opportunity for one
to observe surface reactions with an electrolyte. The rate capability and cyclic performance of the LiCoO2 thin film were enhanced by AlPO4 surface coating. Based on secondary ion mass spectrometry analysis and scanning electron microscopy images of the surface,
it was confirmed that the coating layer was successfully protected from the reactive electrolyte during storage at 90°C. In
contrast, the surface of the pristine sample was severely damaged after storage. 相似文献
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Bong Gill Choi Gyo Hee Kim Kwang Bok Yi Jong-Nam Kim Won Hi Hong 《Korean Journal of Chemical Engineering》2012,29(4):478-482
Although aqueous ammonia solution has been focused on the removal of CO2 from flue gas, there have been very few reports regarding the underlying analysis of the reaction between CO2 and NH3. In this work, we explored the reaction of CO2-NH3-H2O system at various operating temperatures: 40 °C, 20 °C, and 5 °C. The CO2 removal efficiency and the loss of ammonia were influenced by the operating temperatures. Also, infrared spectroscopy measurement
was used in order to understand the formation mechanism of ion species in absorbent, such as NH2COO−, HCO3−, CO32−, and NH4+, during CO2, NH3, and H2O reaction. The reactions of CO2-NH3-H2O system at 20 °C and 40 °C have similar reaction routes. However, a different reaction route was observed at 5 °C compared
to the other operating temperatures, showing the solid products of ammonium bicarbonates, relatively. The CO2 removal efficiency and the formation of carbamate and bicarbonate were strongly influenced by the operating temperatures.
In particular, the analysis of the formation carbamate and bicarbonate by infrared spectroscopy measurement provides useful
information on the reaction mechanism of CO2 in an aqueous ammonia solution. 相似文献
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The electrochemical properties of fluoride-coated lithium cobalt oxide [LiCoO2] thin films were characterized. Aluminum fluoride [AlF3] and lanthanum fluoride [LaF3] coating layers were fabricated on a pristine LiCoO2 thin film by using a spin-coating process. The AlF3- and LaF3-coated films exhibited a higher rate capability, cyclic performance, and stability at high temperature than the pristine
film. This indicates that the AlF3 and LaF3 layers effectively protected the surface of the pristine LiCoO2 film from the reactive electrolyte. 相似文献
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F. Lian P. Axmann C. Stinner Q. G. Liu M. Wohlfahrt-Mehrens 《Journal of Applied Electrochemistry》2008,38(5):613-617
Positive electrode material LiNi1/2Mn1/2O2 was synthesized via the carbonate co-precipitation method and the hydroxide precipitation route to study the effects of the
precursor on its structural and electrochemical properties. The results of X-ray diffraction and Rietveld refinement show
that the carbonate precursor of Ni2+ and Mn2+ exhibits one phase at a pH of 8.5, while the hydroxide deposit separates into Ni(OH)2 and Mn(OH)2 phases under the same experimental conditions. LiNi1/2Mn1/2O2 material prepared from the hydroxide precursor shows 8.9% Li/Ni exchange and a large capacity loss of 11.3% in the first
10 cycles. By contrast, more uniform distribution of transition metal ions and stable Mn2+ in the carbonate precursor contribute to only 7.8% Li/Ni disorder in the obtained LiNi1/2Mn1/2O2, which delivers a reversible capacity of about 182 mAh g−1 at a current rate of 14 mA g−1 between 2.5 and 4.8 V. 相似文献
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Rasoul Khosravi Ahmad Zarei Mohsen Heidari Ali Ahmadfazeli Mehdi Vosughi Mehdi Fazlzadeh 《Korean Journal of Chemical Engineering》2018,35(4):1000-1008
This study considers the feasibility of uptake of cephalexin, an emerging contaminant, from aqueous solutions by using green local montmorillonite (GLM), montmorillonite coated with ZnO (ZnO/GLM) and montmorillonite coated with TiO2 (TiO2/GLM) in the presence of H2O2. Batch adsorption experiments were carried out as a function of pH, initial concentration of the cephalexin, adsorbent dosage, contact time, and temperature. Finally, the adsorbents were characterized by XRD, SEM and FTIR analyses. XRD patterns showed dramatic changes in the adsorbents after loading with the nanoparticles, confirming successful placing of the nanoparticles onto GLM. The GLM mineral surface after nanoparticle loading appears to be fully exposed and more porous with irregular shapes in particles diameters of 1-50 microns. FTIR analyses also confirmed dramatic changes in surface functional groups after modification with these nanoparticles. The results showed that the removal efficiency of cephalexin was better at lower pH values. Totally, the removal efficiency increased with increase in adsorbent dosage and contact time and decreased with concentration and temperature increase. The thermodynamics values of ΔG o and ΔH o revealed that the adsorption process was spontaneous and exothermic. In isotherm study, the maximum adsorption capacities (qm) were obtained to be 7.82, 17.09 and 49.26 mg/g for GLM, ZnO/GLM and TiO2/GLM, respectively. Temkin constant (B T ) showed that adsorption of cephalexin from solution was exothermic for all three adsorbents. 相似文献
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Ho-Sung Yoon Kyung Woo Chung Chul-Joo Kim Jin-Ho Kim Hyung-Seop Lee Seok-Jong Kim Se-Il Lee Seung-Joon Yoo Byung-Chul Lim 《Korean Journal of Chemical Engineering》2018,35(2):470-478
Ferric hydroxide adsorbent was prepared by a chemical treatment process with H2O2, NaOH, and aeration from a Fe2(SO4)3 aqueous solution as a side product discharged from the hydrometallurgical process used to extract neodymium. The ferric hydroxide was used as an adsorbent to prevent eutrophication in water. At the time of synthesis, the most important process variable is the pH condition, which, in this experiment, was changed from pH 3 to 13. The cost of synthesizing ferric hydroxide was sharply reduced by using ferric sulfate, which is considered a side product of the aforementioned hydrometallurgical process, as a starting material, and an adsorbent with high adsorption ability was prepared by controlling the pH level. Microstructural characterization of the synthesized ferric hydroxide revealed particles with a specific surface area of 194.2 m2/g and an average pore diameter of 2.66 nm at pH 6 and 298 K. A column-type packed-bed adsorption experiment was conducted under the following conditions: a flow rate of 0.567 BV/min (3.2 mL/min), 298 K, and atmospheric pressure. The results of the adsorption performance test indicated that the adsorption efficiency of phosphate at concentrations of 10 ppm was 100% at a flow rate of 0.567 BV/min within a contact time of 2 min, and the maximum adsorption capacity for phosphate ions was 65 mg/g. 相似文献
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Shengyao Chen Changhuan Mi Linghao Su Bo Gao Qingbin Fu Xiaogang Zhang 《Journal of Applied Electrochemistry》2009,39(10):1943-1948
LiMn2O4/multi-walled carbon nanotubes (MWNTs) composite was synthesized by mechanical activation reaction followed by a heat-treatment
(500 °C). The LiMn2O4 and LiMn2O4/MWNTs as cathodes were investigated in 1 M Li2SO4 by cyclic voltammetry (CV), galvanostatic charge/discharge (GC), and electrochemical impedance spectroscopy (EIS). The LiMn2O4/MWNTs cathode delivered higher discharge capacity (117 mAh g−1) than LiMn2O4 (84.6 mAh g−1). Furthermore, the results from EIS showed that LiMn2O4/MWNTs had a faster kinetic process for lithium ion intercalation/de-intercalation than LiMn2O4. Besides, LiMn2O4/MWNTs had better cycling stability and rate capability than LiMn2O4, which was confirmed by GC testing. SEM images showed that a three-dimensional network structure was formed during the mechanical
activation, giving a decrease of particle size. 相似文献
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V. M. Talanov V. B. Shirokov V. I. Torgashev G. A. Berger V. A. Burtsev 《Glass Physics and Chemistry》2007,33(6):596-607
The structural mechanisms of formation of the low-symmetry phases of the LiCoO2 compound from the praphase with a sodium chloride structure are investigated in the framework of the Landau phenomenological theory of phase transitions. The possibility of forming new modifications of the LiCoO2 compound is predicted. The calculated structures of some possible low-symmetry phases of lithium cobaltite are described, and the possible phase diagrams are calculated. It is demonstrated that the most stable modifications of the LiCoO2 compound (the spinel-like and rhombohedral modifications) can transform into each other through a first-order phase transition. 相似文献
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The equilibrium composition of the Fe2O3-H2-CO system depending on temperature and pressure was calculated by the methods of chemical thermodynamics at different molar
ratios between the system components. It was found that the equilibrium composition of the mixtures formed in this system
mainly depends on ratios between the system components. The effect of the partial pressures of H2 and CO on the equilibrium
composition of products in the Fischer-Tropsch synthesis was determined. 相似文献
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Won-Joon Choi Jong-Beom Seo Sang-Won Cho Sang-Wook Park Kwang-Joong Oh 《Korean Journal of Chemical Engineering》2009,26(3):705-710
To enhance the absorption rate for CO2 and SO2, aqueous ammonia (NH3) solution was added to an aqueous 2-amino-2-methyl-1-propanol (AMP) solution. The simultaneous absorption rates of AMP and
a blend of AMP+ NH3 for CO2 and SO2 were measured by using a stirred-cell reactor at 303 K. The process operating parameters of interest in this study were the
solvent and concentration, and the partial pressures of CO2 and SO2. As a result, the addition of NH3 solution into aqueous AMP solution increased the reaction rate constants of CO2 and SO2 by 144 and 109%, respectively, compared to that of AMP solution alone. The simultaneous absorption rate of CO2/SO2 on the addition of 1 wt% NH3 into 10 wt% AMP at a p
A1 of 15 kPa and p
A2 of 1 kPa was 5.50×10−6 kmol m−2 s−1, with an increase of 15.5% compared to 10 wt% AMP alone. Consequently, the addition of NH3 solution into an aqueous AMP solution would be expected to be an excellent absorbent for the simultaneous removal of CO2/SO2 from the composition of flue gas emitted from thermoelectric power plants. 相似文献
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The hydrogel of the mixed oxide Al2O3-30% Y0.1Zr0.9O2 was prepared by precipitation of ammonia from a water-alcohol mixture (1 : 5). The Al2O3-30% Y0.1Zr0.9O2 compound thus synthesized was characterized using differential scanning calorimetry, transmission electron microscopy, and
the BET adsorption method. The obtained sample consisted of spherical particles with an average size of 16–20 nm and a specific
surface area of 167 m2/g. The Al2O3-30% Y0.1Zr0.9O2 powder was pressed at 300 MPa and then calcinated at 1600°C for 2 h in air. The topographic and structural features of the
prepared ceramics were determined using atomic force microscopy and X-ray electron probe microanalysis. The porosity, the
Vickers microhardness, and the tensile strength were determined by mercury porometry. 相似文献
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Junyeong Kim Jeong Yeon Do No-Kuk Park Seung Jong Lee Jin-Pyo Hong Misook Kang 《Korean Journal of Chemical Engineering》2018,35(5):1089-1098
Nano-sized bismuth sulfide (Bi2S3) and titanium dioxide (TiO2) with the orthorhombic and anatase tetragonal structures, respectively, were synthesized for application as catalysts for the reduction of carbon dioxide (CO2) to methane (CH4). Four double-layered dense films were fabricated with different coating sequences—TiO2 (bottom layer)/Bi2S3 (top layer), Bi2S3/TiO2, TiO2/Bi2S3: TiO2 (1 : 1) mix, and Bi2S3: TiO2 (1 : 1) mix/Bi2S3: TiO2 (1 : 1) mix—and applied to the photoreduction of CO2 to CH4; the catalytic activity of the fabricated films was compared to that of the pure TiO2/TiO2 and Bi2S3/Bi2S3 doubled-layered films. The TiO2/Bi2S3 double-layered film exhibited superior photocatalytic behavior, and higher CH4 production was obtained with the TiO2/Bi2S3 double-layered film than with the other films. A model of the mechanism underlying the enhanced photoactivity of the TiO2/Bi2S3 double-layered film was proposed, and it was attributed in effective charge separation. 相似文献
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I. E. Gerasimov D. A. Knyazkov A. G. Shmakov A. A. Paletsky V. M. Shvartsberg T. A. Bolshova O. P. Korobeinichev 《Combustion, Explosion, and Shock Waves》2011,47(1):1-11
This paper presents the measurement and simulation data on the thermal and chemical structure of an atmospheric-pressure premixed
H2/O2/N2 flame doped with iron pentacarbonyl Fe(CO)5. Soft ionization molecular beam mass spectrometry was used to measure concentration profiles of the combustion products of
iron pentacarbonyl: Fe, FeO2, FeOH, and Fe(OH)2. A comparison of experimental and simulated concentration profiles showed that they are in satisfactory agreement for FeO2 and Fe(OH)2 and differ significantly for Fe and FeOH. Thus, the previously proposed kinetic model for the oxidation of iron pentacarbonyl
was tested and it was shown that the mechanism needs further elaboration. 相似文献
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L. F. Grigor’eva S. A. Petrov O. Yu. Sinel’shchikova I. A. Drozdova V. V. Gusarov 《Glass Physics and Chemistry》2007,33(1):72-79
The mechanism of formation of barium titanate Ba2Ti9O20 in the BaO-TiO2 and BaO-SrO-TiO2 systems is investigated using initial mixtures prepared by three methods, namely, mechanical grinding of the initial reactants, coprecipitation from aqueous solutions of salts, and the sol-gel technique. It is established that, irrespective of the preparation procedure, the formation of Ba2Ti9O20 proceeds through the formation of the intermediate phases BaTi4O9 and BaTi5O11. The nature of the intermediate phases is determined by the homogeneity and dispersion of the initial mixture, as well as by the stability of the intermediate phase. The most optimum conditions for the synthesis of Ba2Ti9O20 are provided by the formation of BaTi5O11 as an intermediate phase upon heat treatment of the coprecipitation products in the nanocrystalline state. The metastability and structural defects in the BaTi5O11 intermediate phase encourage a decrease in the temperature of the final heat treatment by 100–150°C in the course of the preparation of Ba2Ti9O20 single-phase ceramics. 相似文献
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G. J. Wang L. J. Fu B. Wang N. H. Zhao Y. P. Wu R. Holze 《Journal of Applied Electrochemistry》2008,38(4):579-581
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Wei-Dong Xiang Guo-Yuan Ji Jing Wei Yu-Xiang Yang Xiang-Nong Liu 《Glass Physics and Chemistry》2012,38(2):245-253
Water-soluble Sb2S3 sub-microspheres were synthesized by aqueous-phase arrested precipitation using mercaptoacetic acid as capping agent and
thioacetamide (TAA) as sulfur source. The effects of the experimental conditions, such as temperature, sulfur source, reactants
concentration and reaction time, on the shapes, structures and properties of the products were studied. FESEM, TEM showed
the products have uniform size distribution. In addition, ultraviolet-visible spectrophotometry (UV-vis) and photoluminescence
(PL) showed the resulting products have excellent optical properties. 相似文献
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Nanopowders of solid solutions with different compositions are prepared in the zirconia-enriched region of the ZrO2-CeO2 system. The crystallization of these powders and the formation of the monoclinic, cubic, and tetragonal solid solutions of the composition (Zr1 – x
Cex)O2 are investigated. It is found that the unit cell parameters of the solid solutions increase as the cerium content increases. This confirms the fact that cerium ions [r(Ce4+) = 1.11 ] substitute for zirconium ions [r(Zr4+) = 0.98 ] in these solid solutions. The average size of crystallites of the solid solutions under investigation increases from 5 to 60 nm in the temperature range 500–1200°C.Original Russian Text Copyright © 2005 by Fizika i Khimiya Stekla, Panova, Glushkova, Nefedova. 相似文献
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O. V. Belyaeva T. A. Krasnova S. A. Semenova O. S. Gladkova 《Solid Fuel Chemistry》2011,45(6):418-421
The results of the modification of AG-OV-1 activated carbon under various conditions (by atmospheric oxygen at elevated temperatures
and by hydrogen peroxide or ozone) are given. The effect of the used modifier on changes in the porosity, surface state, and
adsorption capacity of activated carbon is evaluated. 相似文献