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1.
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   

2.
Ion-exchange with different cations (Na+, NH4 +, Li+, Ba2+ and Fe3+) was performed in binderless 13X zeolite pellets. Original and cation-exchanged samples were characterized by thermogravimetric analysis coupled with mass spectrometry (inert atmosphere), X-ray powder diffraction and N2 adsorption/desorption isotherms at 77 K. Despite the presence of other cations than Na (as revealed in TG-MS), crystalline structure and textural properties were not significantly altered upon ion-exchange. Single component equilibrium adsorption isotherms of carbon dioxide (CO2) and methane (CH4) were measured for all samples up to 10 bar at 298 and 348 K using a magnetic suspension balance. All of these isotherms are type Ia and maximum adsorption capacities decrease in the order Li > Na > NH4–Ba > Fe for CO2 and NH4–Na > Li > Ba for CH4. In addition to that, equilibrium adsorption data were measured for CO2/CH4 mixtures for representative compositions of biogas (50 % each gas, in vol.) and natural gas (30 %/70 %, in vol.) in order to assess CO2 selectivity in such scenarios. The application of the Extended Sips Model for samples BaX and NaX led to an overall better agreement with experimental data of binary gas adsorption as compared to the Extended Langmuir Model. Fresh sample LiX show promise to be a better adsorption than NaX for pressure swing separation (CO2/CH4), due to its higher working capacity, selectivity and lower adsorption enthalpy. Nevertheless, cation stability for both this samples and NH4X should be further investigated.  相似文献   

3.
A series of new (MgO) x CuO and (MgO) x MnO2 nanocomposites were prepared and used as adsorbent for removal of As3+, Hg2+, and Pb2+ ions from aqueous solution with high capacity and detection limit. These nanocomposites were synthesized with different molar ratios by sonochemical method in alkaline solution using polyvinylpyrrolidone as a capping agent and were characterized by FTIR, AAS, UV–Vis spectroscopy, and TEM and SEM imaging. The maximum heavy metal ions adsorption was achieved for (MgO)0.32CuO and (MgO)2.9MnO2 nanocomposites assisted by 3-min sonication using ultrasound. Adsorbent capacity of (MgO)0.32CuO reached 500.0 mg/g and detection limit was 0.1 ppb for As3+. Also (MgO)2.9MnO2 nanocomposite adsorbed 457.1 mg/g of Hg2+ and 461.2 mg/g of Pb2+. Extremely low detection limits of 1.5 and 2.0 ppb were obtained for Hg(II) and Pb(II) ions, respectively, which are much lower than the WHO allowable limits. So, these nanocomposites should be excellent candidate for heavy metal removal with advantage of high capacity, high sensitivity, cost effectiveness and easy preparation.  相似文献   

4.
Selective catalytic reduction (SCR) with ammonia has been considered as the most promising technology, as its effect deals with the NOX. Novel Fe-doped V2O5/TiO2 catalysts were prepared by sol–gel and impregnation methods. The effects of iron content and reaction temperature on the catalyst SCR reaction activity were explored by a test device, the results of which revealed that catalysts could exhibit the best catalytic activity when the iron mass ratio was 0.05%. It further proved that the VTiFe (0.05%) catalyst performed the best in denitration and its NOX conversion reached 99.5% at 270 °C. The outcome of experimental procedures: Brunauer–Emmett–Teller surface area, X-ray powder diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, temperature-programmed reduction and adsorption (H2-TPR, NH3-TPD) techniques showed that the iron existed in the form of Fe3+ and Fe2+ and the superior catalytic performance was attributed to the highly dispersed active species, lots of surface acid sites and absorbed oxygen. The modified Fe-doped catalysts do not only have terrific SCR activities, but also a rather broad range of active temperature which also enhances the resistance to SO2 and H2O.  相似文献   

5.
A series of Ce–MnO x /TiO2 catalysts were prepared using a novel sol–gel template method and investigated for low-temperature selective catalytic reduction (SCR) of NO with NH3 at temperatures ranging from 353 to 473 K. The 0.07Ce–MnO x /TiO2 catalyst showed the highest activity and best resistance to SO2 poisoning. The structure and properties of the catalysts were characterized using X-ray diffraction (XRD) analysis, thermogravimetric analysis (TGA), thermogravimetry (TG)–differential scanning calorimetry (DSC)–mass spectroscopy (MS), high-resolution transmission electron microscopy (HRTEM), Brunauer–Emmett–Teller (BET) measurements, H2-temperature-programmed reduction (TPR), and NH3-temperature-programmed desorption (TPD). The superior catalytic activity of the 0.07Ce–MnO x /TiO2 catalyst was probably due to a change in the active components, an increase in surface active oxygen and surface acid sites, and lower crystallinity and larger surface area with Ce doping. Furthermore, the reduction ability also became stronger. The SO2 poisoning resistance of the 0.07Ce–MnO x /TiO2 catalyst improved because doping with Ce can effectively decrease the formation of ammonium salt on the catalyst surface and the sulfation of MnO x . In situ diffuse-reflectance infrared Fourier-transform (DRIFT) spectroscopy experiments indicated that addition of Ce could promote adsorption of NH3 and inhibit generation of some nitryl species. The SCR reactions over the catalysts mainly followed the Eley–Rideal mechanism accompanied with a partial Langmuir–Hinshelwood mechanism.  相似文献   

6.
In this study, a simple approach was described for the fabrication of CaSO4/Fe0 composite used as a novel adsorbent for the reductive removal of Cu2+ from aqueous solutions. The magnetic CaSO4/Fe0 composite was prepared by a solid state reaction at 550 °C in the H2 atmosphere using CaSO4·2H2O/α-FeOOH as a precursor. The structure and morphology of the as-synthesized magnetic composite were characterized by X-ray diffraction, field emission scanning electron microscopy and a superconducting quantum interference device, respectively. Results showed that the CaSO4/Fe0 composite with a rod-like shape could be easily acquired from the CaSO4·2H2O/α-FeOOH precursor with the ratio of 1:0.5 at 550 °C in the H2 atmosphere for 1 h. The CaSO4/Fe0 composite exhibited enhanced performance relevant to the reductive removal of Cu2+. The removal amount of Cu2+ increased linearly with increasing of concentration of Cu2+ in wastewater. Possible removal mechanisms were proposed as follows: (1) the formation of Cu2O by fast reduction of Cu2+ with Fe0 nanoparticles on interface of CaSO4/Fe0 composite, (2) proper adsorption of Cu2+ on the surface of CaSO4/Fe0 composite, (3) the hydrous iron oxide (HIO) such as Fe (OH)3 and FeOOH in situ generated on the rest of CaSO4/Fe0 composite could further adsorb Cu2+ from wastewater.  相似文献   

7.
The NaFeZr(PO4)2SO4 and Pb2/3FeZr(PO4)7/3(SO4)2/3 sulfate phosphates with the NaZr2(PO4)3 (NZP) structure were synthesized and studied using X-ray diffraction, electron microprobe analysis, IR spectroscopy, and simultaneous differential thermal and thermogravimetric analysis. The phase formation and thermal stability of the compounds were studied by powder X-ray diffraction and DTA–TG. The Pb2/3FeZr(PO4)7/3(SO4)2/3 structure was refined by full-profile analysis. The structure framework is composed of randomly occupied (Fe,Zr)O6 octahedra and (P,S)O4 tetrahedra; the Pb2+ ions occupy extra-framework sites. The thermal expansion of Pb2/3FeZr(PO4)7/3(SO4)2/3 in the temperature range from–120 to 200°C was studied by temperature X-ray diffraction. In terms of the average linear coefficient of thermal expansion (αav = 1.7 × 10–6°C–1), this compound can be classified as having low expansion. The combination of different tetrahedral anions (a phosphorus and a smaller sulfur one) in the NZP resulted in a decrease in the framework size and cavities and enabled the preparation of low-expansion sulfate phosphate with a smaller extra-framework cation (cheap Pb) instead of larger cations (Cs, Ba, Sr) used most often in the monoanionic phosphates.  相似文献   

8.
Eu, Dy co-doped strontium aluminate nanophosphors were prepared by the combustion synthesis method. Their structure and morphology were investigated by X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy. According to the XRD and the TEM analysis, the average crystallite size was found to be in the nanometer range. The phase structure of the prepared nanophosphor is consistent with a standard monoclinic phase with a space group P21. The prepared SrAl2O4:Eu2+, Dy3+ nanophosphor emitted green light with a peak at 510 nm showing blue shift, which is due to the reduction in the particle size. Two distinct peaks were observed in the ML intensity versus time curve. The two peaks in ML indicate the presence of charge transfer in an ML process.  相似文献   

9.
Nanocrystalline ThO2:Sm3+ was synthesized using wet-chemical route and characterized using X-ray diffraction (XRD), photoacoustic (PA) and photoluminescence (PL) spectroscopy. PA absorptions of Sm3+ doped samples are found to be quite weak as compared to Nd3+, while PL of Sm3+ was intense. As the energy gap between lowest luminescent levels and highest non-luminescent level in samarium ion is around 7000 cm?1; it is highly fluorescing compared to Nd3+ which has close by levels. Through photoacoustic data it was pointed out that large covalent character exists in ThO2:Nd3+ compared to ThO2:Sm3+.  相似文献   

10.
The Ca2MgSi2O7:Eu2+ and Ca2MgSi2O7:Eu2+, Dy3+ long afterglow phosphors were synthesized under a weak reducing atmosphere by the traditional high temperature solid state reaction method. The synthesized phosphors were characterized by powder X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX) techniques. The luminescence properties were investigated using thermoluminescence (TL), photoluminescence (PL), long afterglow, mechanoluminescence (ML), and ML spectra techniques. The crystal structure of sintered phosphors was an akermanite type structure, which belongs to the tetragonal crystallography. TL properties of these phosphors were investigated, and the results were also compared. Under the ultraviolet excitation, the emission spectra of both prepared phosphors were composed of a broad band peaking at 535 nm, belonging to the broad emission band. When the Ca2MgSi2O7:Eu2+ phosphor is co-doped with Dy3+, the PL, afterglow and ML intensity is strongly enhanced. The decay graph indicates that both the sintered phosphors contain fast decay and slow decay process. The ML intensities of Ca2MgSi2O7:Eu2+ and Ca2MgSi2O7:Eu2+, Dy3+ phosphors were proportionally increased with the increase of impact velocity, which suggests that this phosphor can be used as sensors to detect the stress of an object.  相似文献   

11.
A new sensitive and selective molecularly imprinted electrochemical sensor was developed for Azorubine determination. This sensor was based on molecularly imprinted polymer composed of poly(1-naphthylamine), triphenylamine (as cross-linkers) and dispersed MnO2 nanorod particles on graphite nanopowders. The structure of the prepared nanocomposite was characterized by X-ray powder diffraction, energy-dispersive X-ray spectroscopy, field emission scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. Calibration curve of the imprinted sensor was linear in the concentration range 112 mg L??1 with a detection limit of 0.57 mg L??1. The application of the sensor was checked by the determination of Azorubine in a water sample.  相似文献   

12.
Based on the modulated electronic properties of Fe3O4-graphene (Fe3O4/GN composite) as well as the outstanding complexation between Pb2+ and natural substances garlic extract (GE), a novel electrochemical sensor for the determination of Pb2+ in wastewater was prepared by immobilization of Fe3O4/GN composite integrated with GE onto the surface of glassy carbon electrode (GCE). Fe3O4/GN composite was employed as an electrochemical active probe for enhancing electrical response by facilitating charge transfer while GE was used to improve the selectivity and sensitivity of the proposed sensor to Pb2+ assay. The electrochemical sensing performance toward Pb2+ was appraised by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and square wave voltammetry (SWV). Under the optimized condition, the sensor exhibited two dynamic linear ranges (LDR) including 0.001 to 0.5 nM and 0.5 to 1000 nM with excellent low detection limit (LOD) of 0.0123 pM (S/N =?3) and quantification limit (LOQ) of 0.41 pM (S/N =?10). Meanwhile, it displayed remarkable stability, reproducibility (RSD of 3.61%, n =?3), and selectivity toward the assay for the 100-fold higher concentration of other heavy metal ions. Furthermore, the novel sensor has been successfully employed to detect Pb2+ from real water samples with satisfactory results.  相似文献   

13.
Li2ZnTi3O8/C nanocomposite has been synthesized using phenolic resin as carbon source in this work. The structure, morphology, and electrochemical properties of the as-prepared Li2ZnTi3O8 samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), Raman spectroscopy (RS), galvanostatic charge–discharge, and AC impedance spectroscopy. SEM images show that Li2ZnTi3O8/C was agglomerated with a primary particle size of ca. 40 nm. TEM images reveal that a homogeneous carbon layer (ca. 5 nm) formed on the surface of Li2ZnTi3O8 particles which is favorable to improve the electronic conductivity and inhibit the growth of Li2ZnTi3O8 during annealing process. The as-prepared Li2ZnTi3O8/C composite with 6.0 wt.% carbon exhibited a high initial discharge capacity of 425 and 159 mAh g?1 at 0.05 and 5 A g?1, respectively. At a high current density of 1 A g?1, 95.5 % of its initial value is obtained after 100 cycles.  相似文献   

14.
Natural graphite treated by mechanical activation can be directly applied to the preparation of Li3V2(PO4)3. The carbon-coated Li3V2(PO4)3 with monoclinic structure was successfully synthesized by using natural graphite as carbon source and reducing agent. The amount of activated graphite is optimized by X-ray diffraction, scanning electron microscope, transmission electron microscope, Raman spectrum, galvanostatic charge/discharge measurements, cyclic voltammetry, and electrochemical impedance spectroscopy tests. Our results show that Li3V2(PO4)3 (LVP)-10G exhibits the highest initial discharge capacity of 189 mAh g?1 at 0.1 C and 162.9 mAh g?1 at 1 C in the voltage range of 3.0–4.8 V. Therefore, natural graphite is a promising carbon source for LVP cathode material in lithium ion batteries.  相似文献   

15.
The effect of temperature on the sorption behavior of a synthesized gel structurally close to the fluorine mica mineral, sodium potassium fluorophologopite, was studied for the heavy metal ions Cd2+, Hg2+, and Pb2+. The synthesized gel was characterized by X-ray powder pattern, energy dispersive spectrometry, infrared spectroscopy, and thermogravimetric analysis and was found to have the composition Na0.5K0.5Mg(AlSi3O10)F2·6H2O. The effect of temperature on sorption was studied with respect to varying concentrations of metal ions. The overall sorption capacity of the synthesized gel was found to depend on the number of ion active groups per unit weight of the material. The data were expressed in terms of distribution coefficients (K d). Sorption data followed Freundlich adsorption isotherms. Studies showed that sorption decreased as the concentration of metal ions increased and increased as the temperature grew, which was evidence that the process was endothermic. The text was submitted by the authors in English.  相似文献   

16.
Lithium–sulfur (Li–S) battery is considered as a promising option for electrochemical energy storage applications because of its low-cost and high theoretical capacity. However, the practical application of Li–S battery is still hindered due to the poor electrical conductivity of S cathode and the high dissolution/shuttling of polysulfides in electrolyte. Herein, we report a novel physical and chemical entrapment strategy to address these two problems by designing a sulfur–MnO2@graphene (S–MnO2@GN) ternary hybrid material structure. The MnO2 particles with size of ~ 10 nm are anchored tightly on the wrinkled and twisted GN sheets to form a highly efficient sulfur host. Benefiting from the synergistic effects of GN and MnO2 in both improving the electronic conductivity and hindering polysulfides by physical and chemical adsorptions, this unique S–MnO2@GN composite exhibits excellent electrochemical performances. Reversible specific capacities of 1416, 1114, and 421 mA h g?1 are achieved at rates of 0.1, 0.2, and 3.2 C, respectively. After a 100 cycle stability test, S–MnO2@GN composite cathode could still maintain a reversible capacity of 825 mA h g?1.  相似文献   

17.
Porous network-like MnO2 thick films are successfully synthesized on a flexible stainless steel (SS) mesh using a simple and low-cost electrodeposition method followed by an electrochemical activation process. Morphology, chemical composition, and crystal structure of the prepared electrodes before and after the activation process are determined and compared by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) analyses. The results show that the implementation of the electrochemical activation process does not change the chemical composition and crystal structure of the films, but it influences the surface morphology of the MnO2 thick layer to a flaky nanostructure. Based on the electrochemical data analysis, the maximum specific capacitance of 1400 mF (381 F g?1) and 3700 mF (352 F g?1) are measured for small (2.6 cm2) and large (10 cm2) surface area electrodes, respectively. In addition, a flexible symmetric MnO2//MnO2 solid-state supercapacitor shows a capacitance of 0.3 F with about 98% retention at different bending angles from 0 to 360°.  相似文献   

18.
A novel 1,8-naphthalimide dye with simple structure has been produced by a facile synthetic method for colorimetric and fluorescent sensing of H+ and Cu2+. In CH3CN/H2O (1/1, v/v), the dye could monitor H+ using dual channels (ratiometric absorbance and fluorescence intensity change) from pH 6.2 to 12.0. Meanwhile, in the pH range of 1.9–5.2, the dye could also be used to detect Cu2+ using triple channels [ultraviolet–visible (UV–Vis) absorption, fluorescence intensity reduction, as well as fluorescence blueshift]. The detection limits for Cu2+ evaluated by colorimetric and fluorescent titration were 6.10 × 10?7 and 2.62 × 10?7 M, respectively. The dye exhibited specific selectivity and sensitivity for H+ and Cu2+ over various coexisting metal ions. Moreover, the sensing mechanism of the dye for H+ and Cu2+ was carefully examined.  相似文献   

19.
Reaction of Os2(OAc)4Cl2 with an excess of HDPhF (HDPhF = N,N′-diphenylformamidine) gives a high yield of Os2(DPhF)4Cl2 (1), which can be converted to its azido analog, Os2(DPhF)4(N3)2 (3), by treatment with NaN3. We report a major improvement on the preparation of Os2(chp)4Cl (2; Hchp = 2-chloro-6-hydroxypyridine) by synthesizing the compound in the reducing solvent ethanol. Reaction of 2 with NaN3 affords the azido complex Os2(chp)4N3 (4). Compound 3 has been examined by X-ray crystallography, and has an Os–Os bond distance of 2.45 Å, suggesting a (π*)2 ground state for the molecule.  相似文献   

20.
A yolk–shell-structured sphere composed of a superparamagnetic Fe3O4 core and a carbon shell (Fe3O4@HCS) was etched from Fe3O4@SiO2@carbon by NaOH, which was synthesized through the layer-by-layer coating of Fe3O4. This yolk–shell composite has a shell thickness of ca. 27 nm and a high specific surface area of 213.2 m2 g?1. Its performance for the magnetic removal of tetracycline hydrochloride from water was systematically examined. A high equilibrium adsorption capacity of ca. 49.0 mg g?1 was determined. Moreover, the adsorbent can be regenerated within 10 min through a photo-Fenton reaction. A stable adsorption capacity of 44.3 mg g?1 with a fluctuation <10% is preserved after 5 consecutive adsorption–degradation cycles, demonstrating its promising application potential in the decontamination of sewage water polluted by antibiotics.  相似文献   

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