共查询到12条相似文献,搜索用时 0 毫秒
1.
In situ solvothermally synthesized composite (SSC) and mechanically blended composite (MBC) of nanosized CoSb3 and multiwalled carbon nanotubes (MWNTs) were prepared and investigated as potential anode materials for Li-ion batteries. It was found that SSC exhibits an entanglement structure of nanosized CoSb3 and MWNTs and shows significantly better cycling stability than MBC. The reversible capacity of SSC electrode reaches 312 mA h g−1 at the first cycle and remains above 265 mA h g−1 after 30 cycles. 相似文献
2.
Grigory B. Andreev Nina A. Budantseva Ivan G. Tananaev Boris F. Myasoedov 《Inorganic chemistry communications》2008,11(7):802-804
The reaction of Np(V) methanesulfonate solution with imidazole led to the in situ formation of oxalic acid and the reduction of Np(V) to Np(IV). As a result, the novel organically templated organic polymer, (ImidazoleH)[Np(C2O4)(CH3SO3)3(H2O)2], was formed. The structure consists of infinite chains of [Np(C2O4)(CH3SO3)3(H2O)2]− and imidazolium cations. The crystal structure is confirmed by IR and UV–vis spectroscopic data. This complex is the first example of structurally characterized 1:1 An(IV) oxalate. 相似文献
3.
FTIR spectroscopic investigations coupled with ionic conductivity and viscosity measurements on lithium imide (LiN(CF3SO2)2)-propylene carbonate (PC)-poly(methyl methacrylate) (PMMA) based liquid and gel electrolytes over a wide range of salt (0.025-3 M) and polymer (5-25 wt.%) concentration range furnish a novel insight into the ion-ion and ion-solvent-polymer interactions. Vibrational spectral data for LiN(CF3SO2)2-PC electrolytes reveal that the solvation of lithium ions manifests from Li+OC and Li+O (ring oxygens) interactions as the νs(CO), the ring breathing and the δ(CH) modes of the pentagonal solvent ring are strongly perturbed for all salt concentrations. The split of the ν(SO2) mode (that appears at 1355 cm−1 for the “free imide ion”) into two components at 1337 and 1359 cm−1 confirms the existence of contact ion-pairs possessing two different stable optimized geometries wherein the Li+ ion coordinates in a bidentate fashion in liquid and gel electrolytes of 3 M LiN(CF3SO2)2-PC strength. Perturbations observed for the νa(SNS) and νs(SNS) modes of the imide ion and the symmetric ring deformation mode of PC confirms the presence of ion-pairs in both 2 and 3 M electrolytes. Incorporation of even upto 25 wt.% of PMMA in a solution of LiN(CF3SO2)2-PC of 3 M strength results in an insignificant conductivity decline (as σ25>10−3 S cm−1) which is simultaneously accompanied by a massive increase in its macroscopic viscosity (as η25>108 cSt). Gels containing 25 wt.% of PMMA exhibit a complex pattern of Li+-PMMA interactions through the carbonyl oxygen of its ester group which is evidenced from the perturbations observed for the νs(CO) mode of PMMA. Ionic conductivity decline that occurs at salt concentrations ≥1.25 M LiN(CF3SO2)2-PC in both liquid and gel electrolytes, is therefore attributable to (i) ion-pairing phenomenon and (ii) an enhancement in the solution viscosity due to a high salt proportion. 相似文献
4.
LaxSr2−xMnO4 (0 ≤ x ≤ 0.8) oxides were synthesized and single-phase K2NiF4-type oxides were obtained in the range of 0.1 ≤ x < 0.5. The catalytic activity of LaxSr2−xMnO4 for NO–CO reaction increased with increasing x in the range of solubility limit of La. La0.5Sr1.5MnO4 showed the highest activity among LaxSr2−xMnO4 prepared in this study, but its activity was inferior to perovskite-type La0.5Sr0.5MnO3. Among the Pd-loaded catalysts, however, Pd/La0.8Sr1.2MnO4 showed the higher activity and the selectivity to N2 than Pd/La0.5Sr0.5MnO3 and Pd/γ-Al2O3. The excellent catalytic performance of Pd/La0.2Sr1.2MnO4 could be ascribable to the formation of SrPd3O4 which was detected by XRD in the catalyst but not in the other two catalysts. 相似文献
5.
A μ-Br-bridged dicopper(II) complex, namely [Cu2(μ-Br)2·6H2O](ClO4)2, has been prepared by metal ion grafting. A supported complex catalyst Cu2(II)(μ-Br)2/SiO2was prepared by modifying the silica surface with NaOEt and anchoring the dicopper(II) complex precursor on the surface of the support. The structure of the complex catalyst has been characterized by elemental analysis, IR spectra and UV–VIS diffusion reflection spectra. Obtained data were compared with published data of the complex. TPD-MS and TPD-IR investigations indicated that CO2 and ethylene oxide (EO) can be chemisorbed on the surface of the catalyst reversibly in a bridged state and can be desorbed from the surface at 105 and 115 K, respectively. In the high temperature range of 450–573 K, another reversible absorption state for CO2 was also discovered. For EO, however, a decomposition absorption state was found which gave the dissociated species of CH4 and CO. TPSR-MS experiments have shown that CO2 and EO reacted on the surface effectively in the range of 343–413 K. An in situ IR method has been used to study the reactivity of the reactants on the surface of the catalyst, and the target product ethylene carbonate (EC) was detected in the range of 333–413 K. Catalytic experiments indicated that the one-way yield of EC is greater than 8.0% and that the selectivity of EC is greater than 82%. A synergic cyclization reaction pathway is proposed to account for the observed products. 相似文献
6.
Kee Young Koo Hyun-Seog Roh Yu Taek Seo Dong Joo Seo Wang Lai Yoon Seung Bin Park 《Applied Catalysis A: General》2008,340(2):183-190
MgO-promoted Ni/Al2O3 catalysts have been investigated with respect to catalytic activity and coke formation in combined steam and carbon dioxide reforming of methane (CSCRM) to develop a highly active and stable catalyst for gas to liquid (GTL) processes. Ni/Al2O3 catalysts were promoted through varying the MgO content by the incipient wetness method. X-ray diffraction (XRD), BET surface area, H2-temperature programmed reduction (TPR), H2-chemisorption and CO2-temperature programmed desorption (TPD) were used to observe the characteristics of the prepared catalysts. The coke formation and amount in used catalysts were examined by SEM and TGA, respectively. H2/CO ratio of 2 was achieved in CSCRM by controlling the feed H2O/CO2 ratio. The catalysts prepared with 20 wt.% MgO exhibit the highest catalytic performance and have high coke resistance in CSCRM. MgO promotion forms MgAl2O4 spinel phase, which is stable at high temperatures and effectively prevents coke formation by increasing the CO2 adsorption due to the increase in base strength on the surface of catalyst. 相似文献
7.
Miloš Ognjanović Biljana Dojčinović Martin Fabián Dalibor M. Stanković José F.M.L. Mariano Bratislav Antić 《Ceramics International》2018,44(12):13967-13972
Microstructure and magnetic properties of nanoparticles can be tailored by optimising the synthesis procedure and changing chemical composition. In this study, a two-step procedure, i.e., coprecipitation in the presence of PEG 300 followed by microwave assisted (MW) hydrothermal synthesis, was introduced to obtain CoxFe3-xO4 (x?=?0, 0.1 and 0.2) nanoparticles. It was found that with the increase of Co content, particle/crystallite size increased, with significant change of coercivity (Hc). The mixed samples of CoxFe3-xO4 (x?=?0.1 and 0.2) were magnetically harder in comparison with Fe3O4. Тhe Hc of Fe3O4 was 91?Oe, while for Co0.10Fe2.90O4 and Co0.20Fe2.80O4, Hc was 256?Oe and 1070?Oe, respectively. Saturation magnetisation (Ms) of mixed samples also increased up to 6% compared to Fe3O4. A special effort was devoted to study the effects of introducing different surfactants (PEG 300, PEG 4000 or SDS) during the synthesis procedure in order to improve morphological and microstructural properties of CoFe2O4 nanoparticles. The influence of surfactants on physical/chemical properties of nanoparticles is discussed. 相似文献
8.
V. Matsouka M. Konsolakis R.M. Lambert I.V. Yentekakis 《Applied catalysis. B, Environmental》2008,84(3-4):715-722
The nature and relative populations of adsorbed species formed on the surface of un-promoted and sodium-promoted Pt catalysts supported either on bare Al2O3 or CeO2/La2O3-modified Al2O3, were investigated by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) under simulated automobile exhaust conditions (CO + NO + C3H6 + O2) at the stoichiometric point. The DRIFT spectra indicate that interaction of the reaction mixture with the Pt/Al2O3 catalyst leads mainly to formation of formates and acetates on the support and carbonyl species on partially positively charged Pt atoms (Ptδ+). Although enrichment of Al2O3 with lanthanide elements (CeO2 and La2O3) does not significantly modify the carboxylate species formed on the support, it causes significant modification of the oxidation state of Pt, as indicated by the appearance of a substantial population of carbonyl species on reduced Pt sites (Pt0–CO). This modification of the Pt component is enhanced when Na-promotion is used, leading to formation of carbonyl species only on electron enriched Pt (i.e., fully reduced Pt0 sites) and to the formation of NCO on these Pt entities (2180 cm−1). The latter are thought to result from enhanced NO dissociation at Na-modified Pt sites. These results correlate well with observed differences in the catalytic performance of the three different systems. 相似文献
9.
A novel luminescent Pb(II) coordination framework, {Pb(II)(C6H4O2N)2}n, have been prepared in situ hydrolysis of 4-cyanopyridine under hydrothermal condition and characterized by the elemental analyses, IR spectra, TG and single crystal X-ray diffraction. The compound presents the first framework compound constructed from isonicotinic acids and lead(II) ions, showing three-dimensional architecture with (4, 4) net self-penetrating (48 67) topology. 相似文献
10.
S. Royer H. Alamdari D. Duprez S. Kaliaguine 《Applied catalysis. B, Environmental》2005,58(3-4):273-288
The aim of this work was to study the effect of cation-substitution on the reducibility of the perovskite, as well as the effect on the catalytic activity for the CH4 oxidation reaction. Six perovskites (LaCoO3, LaMnO3, La1−xSrxMnO3 (x = 0.2, 0.4), and La1−xCexMnO3 (x = 0.05, 0.1)) were synthesized by reactive grinding. The reducibility of the perovskite was studied by means of the oxygen storage capacity (OSC) measurement. OSC was performed at different temperatures on LaCoO3 and LaMnO3, in order to elucidate the different mechanisms of reduction involved at each temperature. The substituted samples showed that reduction profile is modified at high-substitution degrees; however, no differences were observed on the OSC values (amount of most active oxygen, calculated after one pulse of CO) between the pure lanthanum sample and the substituted ones.
Tested in the CH4 oxidation reaction, the LaCoO3 sample was found to present a little higher activity than LaMnO3, even if the cobalt-based sample presented a smaller specific surface area. Moreover, all the substituted samples presented very slightly higher activities than the pure LaMnO3 solid. Because of the supposed redox oxidation mechanism (Mars-Van-Krevelen), this agrees well with the OSC results obtained for the reducibility of the manganese on these samples, by which it was observed that substitution does not clearly affect the immediate reduction of the manganese. 相似文献
11.
I. Mukhopadhyay 《Electrochimica acta》2005,50(6):1275-1281
Titanium was electrodeposited from a nominal 0.24 M TiCl4 in l-methyl-3-butyl-imidazolium bis (trifluoro methyl sulfone) imide ([BMIm]BTA) at room temperature on a Au(1 1 1) substrate. The process of electrodeposition was studied by cyclic voltammetry, chrono amperometry and in situ scanning tunneling microscopy (STM). In a first step TiCl4 is reacted to TiCl2, which is subsequently reduced to metallic Ti. Two dimensional (2D) clusters form preferentially on the terraces in the under potential deposition range. 2D clusters presumably of TiCl3 precipitates grow and coalesce to cover the whole substrate with a 2D film at a substrate potential below −1.1 V versus ferricenium/ferrocene ([Fc]+/[Fc]) redox couple. At a potential of −1.8 V a dense layer of three dimensional (3D) clusters of titanium of 1-2 nm thickness is formed. The features of the I-U tunneling spectra and the relative reduction of the effective tunneling barrier by 0.8 eV with respect to gold clearly indicate the metallic character of Ti deposits. Observation of circular holes on the Au(1 1 1) substrate after dissolution of the deposited Ti indicates the formation of Au-Ti surface alloying. 相似文献
12.
Preparations and physico-chemical characterizations of NASICON-type compounds in the system Li1+xAlxA2−xIV(PO4)3 (AIV=Ti or Ge) are described. Ceramics have been fabricated by sol-gel and co-grinding processes for use as ionosensitive membrane for Li+ selective electrodes. The structural and electrical characteristics of the pellets have been examined. Solid solutions are obtained with Al/Ti and Al/Ge substitutions in the range 0≤x≤0·6. A minimum of the rhombohedral c parameter appears for x about 0·1 for both solutions. The grain ionic conductivity has been characterized only in the case of Ge-based compounds. It is related to the carrier concentration and the structural properties of the NASICON covalent skeleton. The results confirm that the Ti-based framework is more calibrated to Li+ migration than the Ge-based one. A grain conductivity of 10−3 S cm−1 is obtained at 25°C in the case of Li1·3Al0·3Ti1·7(PO4)3. A total conductivity of about 6×10−5 S cm−1 is measured on sintered pellets because of grain boundary effects. The use of such ceramics in ISE devices has shown that the most confined unit cell (i.e. in Ge-based materials) is more appropriate for selectivity effect, although it is less conductive.© 相似文献