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1.
Ca3Co4O9 powder was prepared by a polyacrylamide gel route in this paper. The effect of the processing on microstructure and thermoelectric
properties of Ca3Co4O9 ceramics via spark plasma sintering were investigated. Electrical measurement shows that the Seebeck coefficient and conductivity
are 170 μV/K and 128 S/cm, respectively, at 700 °C, yielding a power factor value of 3.70 × 10−4 W m−1 K−2 at 700 °C, which is larger than that of Ca3Co4O9 ceramics via solid-state reaction processing. The polyacrylamide gel processing is a fast, cheap, reproducible and easily
scaled up chemical route to improve the thermoelectric properties of Ca3Co4O9 ceramics by preparing the homogeneous and pure Ca3Co4O9 phase. 相似文献
2.
Phase relations in
the solid state in the FeVO4–Co3V2O8
system, in the whole range of components concentration have been studied.
It was found that the composition of the phase of the howardevansite type
structure, formed in the investigated system, corresponds with the Co2.616Fe4.256V6O24 formula. The phase of the lyonsite type structure
has a homogeneity range with the Co3+1.5xFe4–xV6O24 formula (0.476 formula (0.476<x<1.667).
The melting temperature and the volume of the unit cell of the lyonsite type
structure phase increases together with the rise of cobalt quantity contained
in it. Basing on the results of the DTA and XRD measurements a phase diagram
of the FeVO4–Co3V2O8
system up to the solidus line was constructed. 相似文献
3.
CaAl2O4:Eu2+, Nd3+@TiO2 composite powders were synthesized by a sol–gel method under mild conditions (i.e. low temperature and ambient pressure).
The as-prepared powders were characterized by transmission electron microscopy (TEM) and analyzed by X-ray diffraction (XRD).
The photocatalytic behavior of the TiO2-base surfaces was evaluated by the degradation of nitrogen monoxide gas. It suggested that CaAl2O4:Eu2+, Nd3+@TiO2 composite powders were composed of anatase titania and that CaAl2O4:Eu2+, Nd3+. TiO2 particles were deposited on the surface of CaAl2O4:Eu2+, Nd3+ to form uniform film. CaAl2O4:Eu2+, Nd3+@TiO2 composite powders exhibited higher photocatalytic activity compared with pure TiO2 under visible light. And the result also clearly indicated that the long afterglow phosphor absorbed and stored lights for
the TiO2 to remain photocatalytic activity in the dark. 相似文献
4.
O. V. Nipruk N. G. Chernorukov E. L. Kostrova G. N. Chernorukov 《Russian Journal of Inorganic Chemistry》2016,61(5):572-574
Sodium triuranate Na2(UO2)3O3(OH)2 was synthesized by the reaction between aqueous uranyl acetate solution and aqueous sodium nitrate solution under hydrothermal conditions at 200°C. The composition and structure of the synthesized compound were determined, and its dehydration and thermal decomposition were studied, by chemical analysis, X-ray diffraction, IR spectroscopy, and thermal analysis. 相似文献
5.
Li-Na Xiao Xiang Ding Zhong-Feng Tang Xiao-Dong He Jia-Ying Liao Yan-Hua Cui Chun-Hua Chen 《Journal of Solid State Electrochemistry》2018,22(11):3431-3442
LiNi0.80Co0.15Al0.05O2 (NCA) is explored to be applied in a hybrid Li+/Na+ battery for the first time. The cell is constructed with NCA as the positive electrode, sodium metal as the negative electrode, and 1 M NaClO4 solution as the electrolyte. It is found that during electrochemical cycling both Na+ and Li+ ions are reversibly intercalated into/de-intercalated from NCA crystal lattice. The detailed electrochemical process is systematically investigated by inductively coupled plasma-optical emission spectrometry, ex situ X-ray diffraction, scanning electron microscopy, cyclic voltammetry, galvanostatic cycling, and electrochemical impedance spectroscopy. The NCA cathode can deliver initially a high capacity up to 174 mAh g?1 and 95% coulombic efficiency under 0.1 C (1 C?=?120 mA g?1) current rate between 1.5–4.1 V. It also shows excellent rate capability that reaches 92 mAh g?1 at 10 C. Furthermore, this hybrid battery displays superior long-term cycle life with a capacity retention of 81% after 300 cycles in the voltage range from 2.0 to 4.0 V, offering a promising application in energy storage. 相似文献
6.
In this work, highly chemiluminescent magnetic mesoporous carbon with yolk-shell structure was synthesized by encapsulating N-(4-aminobutyl)-N-ethylisoluminol (ABEI) and Co2+ into the magnetic mesoporous carbon composites (Co2+-ABEI-Fe3O4@ void@C). The synthetic Co2+-ABEI-Fe3O4@void@C showed a good magnetic separation property, which could remove residual ABEI molecules and Co2+ in less than 3 min under an external magnet. Moreover, the synthetic Co2+-ABEI-Fe3O4@void@C demonstrated good chemiluminescence (CL) property and good stability when interacted with alkaline H2O2 solution. The CL intensity of such Co2+-ABEI-Fe3O4@void@C was about 120 times higher than that of ABEI-Fe3O4@void@C. The Co2+-ABEIFe3O4@ void@C also exhibited good electrochemiluminescence (ECL) property in alkaline solution. The outstanding CL/ECL performance of the Co2+-ABEI-Fe3O4@void@C was attributed to the Co2+ immobilized in the Co2+-ABEI-Fe3O4@void@C, which catalyzed the decomposition of H2O2 to generate O2?? and HO?, expediting the CL/ECL reaction. The synthetic Co2+-ABEI-Fe3O4@void@C may be of great application for the development of new methodologies in bioanalysis. 相似文献
7.
Lin Zhou Jing Liu Lisi Huang Na Jiang Qiaoji Zheng Dunmin Lin 《Journal of Solid State Electrochemistry》2017,21(12):3467-3477
Sn-doped Li-rich layered oxides of Li1.2Mn0.54-x Ni0.13Co0.13Sn x O2 have been synthesized via a sol-gel method, and their microstructure and electrochemical performance have been studied. The addition of Sn4+ ions has no distinct influence on the crystal structure of the materials. After doped with an appropriate amount of Sn4+, the electrochemical performance of Li1.2Mn0.54-x Ni0.13Co0.13Sn x O2 cathode materials is significantly enhanced. The optimal electrochemical performance is obtained at x = 0.01. The Li1.2Mn0.53Ni0.13Co0.13Sn0.01O2 electrode delivers a high initial discharge capacity of 268.9 mAh g?1 with an initial coulombic efficiency of 76.5% and a reversible capacity of 199.8 mAh g?1 at 0.1 C with capacity retention of 75.2% after 100 cycles. In addition, the Li1.2Mn0.53Ni0.13Co0.13Sn0.01O2 electrode exhibits the superior rate capability with discharge capacities of 239.8, 198.6, 164.4, 133.4, and 88.8 mAh g?1 at 0.2, 0.5, 1, 2, and 5 C, respectively, which are much higher than those of Li1.2Mn0.54Ni0.13Co0.13O2 (196.2, 153.5, 117.5, 92.7, and 43.8 mAh g?1 at 0.2, 0.5, 1, 2, and 5 C, respectively). The substitution of Sn4+ for Mn4+ enlarges the Li+ diffusion channels due to its larger ionic radius compared to Mn4+ and enhances the structural stability of Li-rich oxides, leading to the improved electrochemical performance in the Sn-doped Li1.2Mn0.54Ni0.13Co0.13O2 cathode materials. 相似文献
8.
A new molybdophosphate (NH4)8{Mo2VO4[(Mo2VIO6)CH3C(O)(PO3)2]2}·14H2O (1), has been synthesized by the reaction of {Mo2VO4(H2O)6}2+ fragments with 1-hydroxyethylidenediphosphonate (hedp HOC(CH3)(PO3H2)2), and it is characterized by 31P NMR, IR, UV, element analysis, TG and single-crystal X-ray analysis. The structure analysis reveals that the polyoxoanion
can be described as two {(Mo2VIO6)(CH3C(O)(PO3)2} units connected by a {Mo2VO4}2+ moiety. In the structure, the six Mo atoms are arranged into a new “W-shaped” structure, which represents a new kind of molybdophosphate. 相似文献
9.
The electrochemical performances of Co3O4 nanopowders, obtained by the sol-gel method, were investigated and compared with those of commercial Co3O4 powders, for oxygen evolution reaction in alkaline solution. The active oxide powder was mixed with teflon and assembled
on Ti substrate to form thin catalyst film. Cyclic voltammetry, polarization curves, and electrochemical impedance spectroscopy
were used to assess the mechanism of oxygen evolution reaction, chemical structure, and morphology of the catalyst.
Presented at the 33rd International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 22–26 May
2006. 相似文献
10.
Ashok Kumar Chakraborty Md. Rashidul Islam Md. Helal Uddin Md. Masudur Rhaman 《Journal of Cluster Science》2018,29(1):67-74
A highly efficient and visible light (λ ≥ 420 nm) responsive composite photocatalyst, Co3O4/FeWO4 was prepared by simple impregnation method. The heterojunction semiconductors Co3O4/FeWO4 demonstrated notably high photocatalytic activity over a wide range of composition than the individual component Co3O4 or FeWO4 for the complete degradation of 1,4-dichlorobenzene (DCB) in aqueous phase under visible light irradiation. The photocatalytic activity of composite was optimized at 1/99 Co3O4/FeWO4 composition. After 2 h of visible light irradiation 51% decomposition of 1,4-dichlorobenzene (DCB) was observed utilizing 1/99 Co3O4/FeWO4 photocatalyst while the end members demonstrated a negligible degradation under the same experimental condition. The valence band (VB) and conduction band (CB) of Co3O4 is located above the VB and CB of FeWO4, respectively. Both the semiconductors Co3O4 and FeWO4 exhibit strong absorption over the wide range of visible light. The obviously enhanced photocatalytic performance of Co3O4/FeWO4 composite has been discussed on the hole (h+) as well as electron (e?) transfer mechanism between the VB and CB of individual semiconductors. 相似文献
11.
S. X. Wang L. X. Sun Z. C. Tan F. Xu Y. S. Li 《Journal of Thermal Analysis and Calorimetry》2007,89(2):609-612
Conducting polyaniline/Cobaltosic oxide (PANI/Co3O4) composites were synthesized for the first time, by in situ deposition technique in the presence of hydrochloric acid (HCl)
as a dopant by adding the fine grade powder (an average particle size of approximately 80 nm) of Co3O4 into the polymerization reaction mixture of aniline. The composites obtained were characterized by infrared spectra (IR)
and X-ray diffraction (XRD). The composition and the thermal stability of the composites were investigated by TG-DTG. The
results suggest that the thermal stability of the composites is higher than that of the pure PANI. The improvement in the
thermal stability for the composites is attributed to the interaction between PANI and nano-Co3O4. 相似文献
12.
Ag/Al2O3 is a promising catalyst for the selective catalytic reduction (SCR) by hydrocarbons (HC) of NO
x
in both laboratory and diesel engine bench tests. New developments of the HC-SCR of NO
x
over a Ag/Al2O3 catalyst are reviewed, including the efficiencies and sulfur tolerances of different Ag/Al2O3-reductant systems for the SCR of NO
x
; the low-temperature activity improvement of H2-assisted HC-SCR of NO
x
over Ag/Al2O3; and the application of a Ag/Al2O3-ethanol SCR system with a heavy-duty diesel engine. The discussions are focused on the reaction mechanisms of different Ag/Al2O3-reductant systems and H2-assisted HC-SCR of NO
x
over Ag/Al2O3. A SO2-resistant surface structure in situ synthesized on Ag/Al2O3 by using ethanol as a reductant is proposed based on the study of the sulfate formation. These results provide new insight
into the design of a high-efficiency NO
x
reduction system. The diesel engine bench test results showed that a Ag/Al2O3-ethanol system is promising for catalytic cleaning of NO
x
in diesel exhaust. 相似文献
13.
The kinetics of oxidation of CH4 to formaldehyde on the catalytic system Na4[PFeMo11O40]/SiO2 were studied, and a significant role of the redox potential of the CH4-O2 system with respect to the catalyst was shown. The density of centers participating in the reaction was determined, and dissociative competitive adsorption of methane and oxygen was established. The equation was deduced in the framework of the Langmuir-Hinshelwood theory taking into account the side conversion of formaldehyde. Possible participation of lattice oxygen in the reaction was suggested. 相似文献
14.
Composition and properties were studied of products formed in treatment of solid Na2CO3 with aqueous solutions containing acetic and citric acids with mass fractions of 0.40–0.60 and 0.33–0.49, respectively, at a Na2CO3/H x An molar ratio of 2–6, where H x An = CH3COOH and H3(C6H5O7). It was found that the content of water in the systems under study and the strength of an acid affect the yield of the double salt of carbonic acid, Na2CO3·NaHCO3·2H2O and the composition of derivative proton-containing compounds. It is noted that sodium sesquicarbonate can be formed both by the crystallization mechanism and via a transformation of the primary structure of sodium carbonate. In the resulting powder-like products, water introduced with the acid solution is predominantly consumed for formation of crystal hydrates of carbonate-containing and derivative proton-containing compounds. The hygroscopic point of the resulting salt formulations was determined to be at a level of 70–75%. It was noted that sesquicarbonate-containing salt formulation formed in “dry” neutralization of sodium carbonate by acid solutions can be regarded as a builder for obtaining synthetic household detergents. 相似文献
15.
G. Nenartaviciene K. Tõnsuaadu D. Jasaitis A. Beganskiene A. Kareiva 《Journal of Thermal Analysis and Calorimetry》2007,90(1):173-178
In this study the formation of chromium substituted YBa2Cu4O8 (Y-124) superconductors has been investigated by TG/DTA measurements. The YBa2(Cu1−xCrx)4O8 ceramics with nominal compositions of x=0.01, 0.03, 0.05, 0.10 and 0.20 have been prepared by an aqueous sol-gel method using aqueous mixtures of the corresponding
metal acetates and nitrates. Homogeneous precursor gels were obtained by complexing metal ions with tartaric acid. To assist
the interpretation of the results obtained the synthesis products were additionally characterized by X-ray powder diffraction
(XRD) and resistivity measurements. It was determined that doping the YBa2Cu4O8 phase with chromium has a strong effect on the phase purity and superconducting properties of the synthesis products. 相似文献
16.
Differential scanning calorimetry (DSC) and thermomechanical analysis (TMA) were used to study the thermal behaviour of (50-x)Na2O-xTiO2-50P2O5 and 45Na2O-yTiO2-(55-y)P2O5 glasses. The addition of TiO2 to the starting glasses (x=0 and y=5 mol% TiO2) resulted in a nonlinear increase of glass transition temperature and dilatation softening temperature, whereas the thermal
expansion coefficient decreased. All prepared glasses crystallize under heating within the temperature range of 300–610°C.
The contribution of the surface crystallization mechanism over the internal one increases with increasing TiO2 content. With increasing TiO2 content the temperature of maximum nucleation rate is also gradually shifted from a value close to the glass transition temperature
towards the crystallization temperature. X-ray diffraction measurements showed that the major compounds formed by glass crystallization
were NaPO3, TiP2O7 and NaTi2(PO4)3. The chemical durability of the glasses without titanium oxide is very poor, but with the replacement of Na2O or P2O5 by TiO2, it increases sharply. 相似文献
17.
YBaCo4O7 compound is capable to intake and release a large amount of oxygen in the temperature range of 200–400°C. In the present
study, the effect of Zn, Ga and Fe substitution for Co on the oxygen adsorption/desorption properties of YBaCo4O7 were investigated by thermogravimetry (TG) method. Due to fixed oxidation state of Zn2+ ions, the substitution of Zn2+ for Co2+ suppresses the oxygen adsorption of YBaCo4−xZnxO7. The substitution of Ga3+ for Co3+ also decreases the oxygen absorption capacity of YBaCo4−xGaxO7. This can be explained by the strong affinity of Ga3+ ions towards the GaO4 tetrahedron. Compared with Zn- and Ga-substituted samples, the drop of oxygen adsorption capacity is smallest for Fe-substituted
samples because of the similar changeability of oxidation states of Co and Fe ions. 相似文献
18.
New composite cathode materials xLiMn2O4/(1 ? x) LiCoO2(x = 0.7, 0.6, 0.5 и 0.4) were obtained by mechanical activation. According to scanning electron microscopy data, the process was accompanied by pronounced dispersion and fine mixing of the initial components. In the course of the preparation and electrochemical cycling of the composites, LiMn2O4 and LiCoO2 partially reacted, leading to the replacement of manganese with cobalt in the structure of spinel, which was detected by powder X-ray diffraction (XRD), IR and X-ray photoelectron spectroscopy (XPS), and cyclic chronopotentiometry. The specific discharge capacity of composites was ~100 mAh/g. 相似文献
19.
Co3O4 crystallites with particle, plate-, tube-, rod- and sheet-like morphologies were successfully prepared by the calcination
of the corresponding precursors synthesized via a precipitation or hydrothermal procedure. The morphologies of the precursors
and Co3O4 nano-tubes were detected by field emission scanning electron microscopy (FE-SEM). The as-obtained Co3O4 samples were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis
(TGA) and special surface area measurement (BET). The electrocatalytic activity of p-nitrophenol reduction with the Co3O4 products decorated on a glassy carbon electrode (GCE) was tested, respectively, using cyclic voltammetry (CV) in a basic
solution. The results indicated that p-nitrophenol was reduced with higher current density but almost at a constant potential on the Co3O4/GCE in contrast with that on a bare GCE at the same conditions. The highly catalytic activity of the as-prepared Co3O4 in a basic solution suggested their wide applications in environmental treatment or organic synthesis. 相似文献
20.
Z. A. Mikhailovskaya E. S. Buyanova S. A. Petrova M. V. Morozova R. G. Zakharov V. M. Zhukovskii 《Russian Journal of Inorganic Chemistry》2013,58(6):695-700
The existence boundaries, structures, and transport parameters of Bi1 ? x Co x [Bi12O14]Mo5O20 ± δ and Bi[Bi12O14]Mo5 ? y Co y O20 ± δ solid solutions, which have a unique columnar structure, were studied. Electrical conductivity in these solid solutions was studied by impedance spectroscopy. 相似文献