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1.
The molecular imprinting technique is powerful to prepare functional materials with molecular recognition properties. In this work, a potentiometric sensor was fabricated by dispersing molecularly imprinted polymers (MIPs) into plasticized PVC matrix and used for the determination of 1-hexyl-3-methylimidazolium cation ([C6mim]+) in aqueous solution. The MIPs were synthesized by precipitation polymerization using 1-hexyl-3-methylimidazolium chloride ([C6mim]Cl) as the template molecule, methacrylic acid (MAA) and ethylene glycol dimethacrylat (EGDMA) as the functional monomers, and EGDMA also as the cross-linking agent. The as-prepared electrode exhibited a Nernstian response (58.87 ± 0.3 mV per decade) to [C6mim]+ in a concentration range from 1.0 × 10−6 to 0.1 mol kg−1 with a low detection limit of 2.8 × 10−7 mol kg−1, high selectivity, and little pH influence. The as-prepared electrode was used for the detection of the [C6mim]+ in distilled water, tap water, and river water with a good recovery. It was also successfully applied in the determination of mean activity coefficients of [C6mim]Br in fructose + water systems based on the potentiometric method at 298.15 K. 相似文献
2.
Ni-based cermets were prepared and reduced from mixtures of NiO and Ba 2In 0.6Ti 1.4O 5.7□ 0.3. A cermet containing 18.7 vol.% of Ni exhibits promising characteristics: 40% of open porosity and a lower DC resistivity than a Ni/YSZ cermet with a larger Ni content (30 vol.%). Its thermal expansion coefficient is 11.4 × 10 − 6 K − 1 whereas that measured for Ba 2In 0.6Ti 1.4O 5.7□ 0.3 is 9.9 × 10 − 6 K − 1. Electrical measurements vs. the Ni content have shown that the percolation threshold corresponds to 15.7 vol.% of Ni. By using saccharose as a pore former, the porosity of the electrode can be tuned. It is shown that the pore size is controlled by the particle size distribution of the pore former. 相似文献
3.
The 19-electron VCoSb compounds are actually composites of an off-stoichiometric half-Heusler phase and impurities. Here the compositional adjustment is systematically studied in V 1−xCoSb to obtain single-phase V 0.955CoSb. Hall measurements suggest that such a V vacancy, as well as Ti doping, can optimize the carrier concentration, which decreases from ≈11.3 × 10 21 cm −3 for VCoSb to ≈6.3 × 10 21 cm −3 for V 0.755Ti 0.2CoSb. Low sound velocity contributes to the intrinsically low lattice thermal conductivity for VCoSb-based materials. The high Ti-dopant content results in enhanced point-defect scattering, which further decreases the lattice thermal conductivity. Finally, the optimized n-type V 0.855Ti 0.1CoSb is found to reach a peak ZT of ≈0.7 at 973 K. The work demonstrates that the VCoSb-based half-Heuslers are promising thermoelectric materials. 相似文献
4.
Ultrahigh-aspect-ratio V 2O 5 nanowires were successfully prepared using [VO(O 2) 2(OH 2)] − as the starting material by a template-free hydrothermal route without the addition of organic surfactant or inorganic ions. The prepared samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmet–Teller (BET), cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD). The results revealed that the peroxovanadium (V) complexes can be easily transformed to V 2O 5 nanowires by this hydrothermal route. The uniform nanowires were with width about 50 nm and length about dozens of micron. The BET analysis showed the V 2O 5 nanowires had a high specific surface area of 25.6 m 2 g −1. The synthesized V 2O 5 nanowires performed a high capacitance of 351 F g −1 when used as supercapacitor electrode in 1 mol L −1 LiNO 3. 相似文献
5.
Binder-free thickness-controllable Li 4Ti 5O 12 for application in lithium ion batteries was fabricated by the reaction of Li 2CO 3 and anodic nanotubular TiO 2 at 800 °C. As the concentration of Li 2CO 3 increased, the thickness of Li 4Ti 5O 12 film increased, leading to increase in discharge capacity. The Li 4Ti 5O 12 film prepared at the optimized concentration of Li 2CO 3 of 3.8 × 10 ?6 mol displayed the maximum capacity of 104 μA h cm ?2 at the first cycle, which corresponds to 103 mA h g ?1. We found that excess Li 2CO 3 led to creation of LiTiO 2 phases in the Li 4Ti 5O 12 film, which reduced the discharge capacity. For comparison, a Li 4Ti 5O 12 film was prepared by the reaction of Li 2CO 3 on a non-anodized Ti foil. In this case, discharge capacity was dramatically reduced due to the formation of Li 2TiO 3 phases in Li 4Ti 5O 12, which was confirmed by TEM and XRD analysis. 相似文献
6.
We report the studies on quasi-solid battery-supercapacitor (BatCap) systems fabricated using sol–gel-prepared LiFePO4 and its composites (LACs) with activated charcoal (AC) as hybrid cathode and Li4Ti5O12 powder as anode separator by flexible gel polymer electrolyte (GPE) film. The GPE film comprises 1.0 M lithium trifluoromethane sulfonate (LiTf) solution in ethylene carbonate (EC)–propylene carbonate (PC) mixture, immobilized poly(vinylidene fluoride-co-hexafluoro-propylene) (PVdF-HFP), which is of high ionic conductivity (∼3.8 × 10−3 S cm−1 at 25 °C) and electrochemical stability window (∼3 V). The effect of the addition of AC in composite electrode LACs has been analyzed using various techniques such as X-ray diffraction, porosity analysis, and electrochemical methods. The interfaces of composite LACs and GPE film not only offer high rate performance but also show high specific energy (>27.8 Wh kg−1) as compared to the symmetric supercapacitors and pristine lithium iron phosphate (LiFePO4)-based lithium ion batteries. The full BatCap systems have been characterized by cyclic voltammetry and galvanostatic charge–discharge tests. The BatCap systems with composite electrodes (LACs) offer better cyclic performance as compared to that of pristine LiFePO4-based BatCap or LIB LiFePO4/Li4Ti5O12. 相似文献
7.
Ge 2Sb 2Te 5 is a famous phase-change memory material for rewriteable optical storage, which is widely applied in the information storage field. The stable trigonal phase of Ge 2Sb 2Te 5 shows potential as a thermoelectric material as well, due to its tunable electrical transport properties and low lattice thermal conductivity. In this work, the carrier concentration and effective mass of Ge 2Sb 2Te 5 are modulated by substituting Te with Se. Meanwhile, the thermal conductivity reduces from 2.48 W m −1 K −1 for Ge 2Sb 2Te 5 to 1.37 W m −1 K −1 for Ge 2Sb 2Te 3.5Se 1.5 at 703 K. Therefore, the thermoelectric figure of merit zT increases from 0.24 for Ge 2Sb 2Te 5 to 0.41 for Ge 2Sb 2Te 3.5Se 1.5 at 703 K. This study reveals that Se alloying is an effective way to enhance the thermoelectric properties of Ge 2Sb 2Te 5. 相似文献
8.
The scintillation timing characteristics of (La,Gd) 2Si 2O 7:Ce (GPSLa23.5%:Ce) single crystal were studied and compared with Gd 2SiO 5:Ce (GSO:Ce) single crystal. The photoelectron yield, scintillation decay times and coincidence time resolution were measured. At 511 keV γ-rays, the photoelectron yield of 10,770 ± 500 phe MeV −1 and energy resolution of 5.4 ± 0.2% obtained for GPSLa23.5%:Ce are much better than those of 3350 ± 160 phe MeV −1 and 7.8 ± 0.3% obtained for GSO:Ce. The scintillation decay time profile was measured by the time-correlated single photon counting technique using a fast-slow coincidence setup. In both materials the comparable rise times of several nanoseconds are present. The fast component decay time of 56 ns with relative intensity of 49% obtained for GPSLa23.5%:Ce is inferior to that of 32 ns(88%) obtained for GSO:Ce. Consequently, the coincidence time resolution of GPSLa23.5%:Ce is slightly worse than that of GSO:Ce. The normalized time resolution was also discussed in terms of a number of photoelectrons and decay time of the scintillation pulse. 相似文献
9.
In this study, vanadium pentoxide (V 2O 5) nanowires (NWs) with a diameter of 100–200 nm and a length of up to several micrometers as cathode for lithium ion batteries are synthesize using an electrospinning method. The reduced graphene oxide (rGO) and V 2O 5 NWs (GVO) composites are form by wet mixing the electrospun V 2O 5 NWs and rGO. Surface morphologies, microstructure and elemental mapping, and chemical bonding states of the composites are characterize. The initial and 60 cycles discharge capacities of GVO composite composed of 1 wt% rGO show up to 225 mAh g −1 and 125 mAh g −1, even higher than pure V 2O 5 NWs, when the lithium ion battery cycled between 2.0 and 4.0 V with a rate of 0.2 C, because of highly conductive rGO. The GVO composite could be promising as a high performance cathode for lithium ion batteries. 相似文献
10.
The Lu 2+xTi 2−xO 7−x/2 ( x = 0; 0.052; 0.096; 0.286; 0.44; 0.63; 33.3–49 mol% Lu 2O 3) nanoceramics with partly disordered pyrochlore-type structure are prepared by sintering freeze-dried powders obtained by a co-precipitation technique with 1600 °C annealing. Similar to pyrochlore-like compositions in the zirconate system, some of the new titanates are good oxide-ion conductors in air. The new solid-state electrolytes have oxide-ion conductivity in the interval of 1.0 × 10 − 3 – 2.5 × 10 − 3 S/cm at 740 °C in air. This value of conductivity is comparable with that of ZrO 2/Y 2O 3 ceramics. The conductivity of Lu 2+xTi 2−xO 7−x/2 depends on the chemical composition. The highest ionic conductivity is exhibited by nearly stoichiometric Lu 2+xTi 2−xO 7−x/2 ( x = 0.096; 35.5 mol% Lu 2O 3) material containing ∼ 4.8 at.% Lu Ti anti-site defects. 相似文献
11.
Oxygen-ionic and electronic transport in dense (SrFe) 1−x(SrAl 2) xO z composites, consisting of strontium-deficient Sr(Fe,Al)O 3-δ and SrAl 2O 4 phases, is determined by the properties of perovskite-like solid solution. Increasing the content of SrAl 2O 4, with a total conductivity as low as 5 × 10 − 7 − 10 − 5 S × cm − 1 at 973–1273 K in air, results in the gradual decrease of the partial conductivities, but also enables the suppression of thermal expansion. Compared to single-phase SrFe 1−xAl xO 3-δ, (SrFe) 1−x(SrAl 2) xO z composites exhibit enhanced thermomechanical properties, while the oxygen permeability of these materials has similar values. The composite membranes exhibit stable performance under air/(H 2–H 2O–N 2) and air/(CH 4–He) gradients at 973–1173 K. The oxidation of dry methane by oxygen permeating through (SrFe) 0.7(SrAl 2) 0.3O z results in dominant total oxidation, suggesting the necessity to incorporate a reforming catalyst into the ceramic reactors for natural gas conversion. 相似文献
12.
Single crystals of gadolinium orthosilicate Gd 2SiO 5 containing 0.5 at% and 5 at% of Sm 3+ were grown by the Czochralski method. Optical absorption spectra, luminescence spectra and luminescence decay curves were
recorded for these systems at 10 K and at room temperature. Comparison of optical spectra recorded in polarized light revealed
that the anisotropy of this optically biaxial host affects the intensity distribution within absorption and emission bands
related to transitions between multiplets rather than the overall band intensity. It has been found that among four bands
of luminescence related to the 4G 5/2→ 6H J (J=5/2–11/2) transitions of Sm 3+ in the visible and near infrared region the 4G 5/2 → 6H 7/2 one has the highest intensity with a peak emission cross section of 3.54×10 −21 cm 2 at 601 nm for light polarized parallel to the crystallographic axis c of the crystal. The luminescence decay curve recorded
for Gd 2SiO 5:0.5 at% Sm 3+ follows a single exponential time dependence with a lifetime 1.74 ms, in good agreement with the 4G 5/2 radiative lifetime τ
rad=1.78 ms calculated in the framework of Judd-Ofelt theory. Considerably faster and non-exponential luminescence decay recorded
for Gd 2SiO 5:5 at% Sm 3+ sample was fitted to that predicted by the Inokuti-Hirayama theory yielding the microparameter of Sm 3+–Sm 3+ energy transfer C
da=1.264×10 −52 cm 6×s −1. 相似文献
13.
Ta 2O 5/Al 2O 3 stacked thin film was fabricated as the gate dielectric for low-voltage-driven amorphous indium–gallium–zinc-oxide (IGZO) thin film transistors (TFTs). The Ta 2O 5/Al 2O 3 stacked thin film exhibits a combination of the advantages of Al 2O 3 and Ta 2O 5. The IGZO TFT with Ta 2O 5/Al 2O 3 stack exhibits good performance with large saturation mobility of 26.66 cm 2 V −1 s −1, high on/off current ratio of 8 × 10 7, and an ultra-small subthreshold swing ( SS) of 78 mV/decade. Such small SS value is even comparable with that of submicrometer single-crystalline Si MOSFET. 相似文献
14.
The elaboration of LaZr2Cr4Ni5-based intermetallic compound was performed by mechanical alloying from LaNi5 and ZrCr2 precursors and characterized as active materials of negative electrodes in nickel-metal hydride (Ni-MH) batteries. The effect of the milling duration on the phase composition was investigated. The structural properties of the formed phases were determined by X-ray diffraction and quantified from the Rietveld refinement data. The increase of the milling time up to 40 h leads to the highest abundance of the LaZr2Cr4Ni5 phase, estimated at a weight content of 60.6 %, and a complete elimination of the LaNi5 intermetallic precursor. The chronopotentiometry, cyclic voltammetry, and chronoamperometry techniques were applied to characterize the electrochemical behavior of prepared LaZr2Cr4Ni5-based compounds. The maximum discharge capacity was 152 mAh g−1, and a high electrochemical stability was obtained in the alkaline solution. The value of the hydrogen diffusion coefficient is equal to 2.1 × 10−8 cm2 s−1, reflecting an appropriate electrochemical hydrogenation kinetic in the LaZr2Cr4Ni5-based compounds. 相似文献
15.
The sonocatalytic degradation of EDTA (C 0 = 5 10 −3 M) in aqueous solutions was studied under 345 kHz (P ac = 0.25 W mL −1) ultrasound at 22–51 °C, Ar/20%O 2, Ar or air, and in the presence of metallic titanium (Ti 0) or core-shell Ti@TiO 2 nanoparticles (NPs). Ti@TiO 2 NPs have been obtained using simultaneous action of hydrothermal conditions (100–214 °C, autogenic pressure P = 1.0–19.0 bar) and 20 kHz ultrasound, called sonohydrothermal (SHT) treatment, on Ti 0 NPs in pure water. Ti 0 is composed of quasi-spherical particles (30–150 nm) of metallic titanium coated with a metastable titanium suboxide Ti 3O. SHT treatment at 150–214 °C leads to the oxidation of Ti 3O and partial oxidation of Ti 0 and formation of nanocrystalline shell (10–20 nm) composed of TiO 2 anatase. It was found that Ti 0 NPs do not exhibit catalytic activity in the absence of ultrasound. Moreover, Ti 0 NPs remain inactive under ultrasound in the absence of oxygen. However, significant acceleration of EDTA degradation was achieved during sonication in the presence of Ti 0 NPs and Ar/20%O 2 gas mixture. Coating of Ti 0 with TiO 2 nanocrystalline shell reduces sonocatalytic activity. Pristine TiO 2 anatase nanoparticles do not show a sonocatalytic activity in studied system. Suggested mechanism of EDTA sonocatalytic degradation involves two reaction pathways: (i) sonochemical oxidation of EDTA by OH /HO 2 radicals in solution and (ii) EDTA oxidation at the surface of Ti 0 NPs in the presence of oxygen activated by cavitation event. Ultrasonic activation most probably occurs due to the local heating of Ti 0/O 2 species at cavitation bubble/solution interface. 相似文献
16.
Compatible with existing processing technology, chemical vapor deposition method is used to synthesize ZrS 2 and HfS 2 films a a large scale. The nonlinear optical properties are characterized by Z-scan measurement with femtosecond pulses at 800 nm. The results show that saturable absorption happens in ZrS 2 owing to the larger ground state absorption than the excited state absorption, while reverse saturable absorption appears in HfS 2 due to the two-photon absorption. The figure of merit values of ZrS 2 (≈4.30 ± 0.12 × 10 −15 esu cm) and HfS 2 (≈6.0 ± 1.4 × 10 −15 esu cm) are much larger than those of MoS 2 and graphene in ultrafast nonlinear optical performance at the wavelength of 800 nm. 相似文献
17.
The defects in Cr 2−xTi xO 3 ( x = 0, 0.2 and 0.3) were studied by a combination of X-ray diffraction, density and electrical conductivity measurements supported by atomistic simulation. The results are consistent with the Ti being dissolved as Ti 4+ compensated by Cr vacancies which associate to form complex defects of lower energy. Ti doping gives n-type semiconductivity due to a small concentration of Ti 3+ in equilibrium with the complexes. 相似文献
18.
Stacked-nanoflake Li 4Ti 5O 12 spinel was synthesized via the pyrolysis of a Li–Ti copolymeric precursor formed by in situ polymerization of LiOH and [Ti(OC 4H 9) 4] and acrylic acid. XRD and SEM characterization shows that the powders calcined at 700 °C for 3 h was well-crystallized particles with submicron diameter. Charge–discharge measurement showed the Li 4Ti 5O 12 electrode had displayed excellent rate capability and delivered reversible capacity of 171, 158, 148, 138 and 99 mAh g −1 at rates of 0.1C, 0.5C, 1C, 2C and 4C, respectively. The test electrode also showed excellent cyclability as the capacity retains 96.1% after 60 cycles between 0.5 and 2.5 V. 相似文献
19.
In this study, a novel hydrodynamic cavitation unit combined with a glow plasma discharge system (HC-GPD) was proposed for the degradation of pharmaceutical compounds in drinking water. Metronidazole (MNZ), a commonly used broad-spectrum antibiotic, was selected to demonstrate the potential of the proposed system. Cavitation bubbles generated by hydrodynamic cavitation (HC) can provide a pathway for charge conduction during glow plasma discharge (GPD). The synergistic effect between HC and GPD promotes the production of hydroxyl radicals, emission of UV light, and shock waves for MNZ degradation. Sonochemical dosimetry provided information on the enhanced formation of hydroxyl radicals during glow plasma discharge compared to hydrodynamic cavitation alone. Experimental results showed a MNZ degradation of 14% in 15 min for the HC alone (solution initially containing 300 × 10 −6 mol L −1 MNZ). In experiments with the HC-GPD system, MNZ degradation of 90% in 15 min was detected. No significant differences were observed in MNZ degradation in acidic and alkaline solutions. MNZ degradation was also studied in the presence of inorganic anions. Experimental results showed that the system is suitable for the treatment of solutions with conductivity up to 1500 × 10 −6 S cm −1. The results of sonochemical dosimetry showed the formation of oxidant species of 0.15 × 10 −3 mol H 2O 2 L −1 in the HC system after 15 min. For the HC-GPD system, the concentration of oxidant species after 15 min reached 13 × 10 −3 mol H 2O 2 L −1. Based on these results, the potential of combining HC and GPD systems for water treatment was demonstrated. The present work provided useful information on the synergistic effect between hydrodynamic cavitation and glow plasma discharge and their application for the degradation of antibiotics in drinking water. 相似文献
20.
A red-emitting phosphor material, Gd 2Ti 2O 7:Eu 3+, V 4+, by added vanadium ions is synthesized using the sol-gel method. Phosphor characterization by high-resolution transmission electron microscopy shows that the phosphor possesses a good crystalline structure, while scanning electron microscopy reveals a uniform phosphor particle size in the range of 230-270 nm. X-ray photon electron spectrum analysis demonstrates that the V 4+ ion promotes an electron dipole transition of Gd 2Ti 2O 7:Eu 3+ phosphors, causing a new red-emitting phenomenon, and CIE value shifts to x=0.63, y=0.34 (a purer red region) from x=0.57, y=0.33 (CIE of Gd 2Ti 2O 7:Eu 3+). The optimal composition of the novel red-emitting phosphor is about 26% of V 4+ ions while the material is calcinated at 800 °C. The results of electroluminescent property of the material by field emission experiment by CNT-contained cathode agreed well with that of photoluminescent analysis. 相似文献
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