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1.
Three kinds of sulfonated poly(ether ether ketone) (SPEEK)/nano oxide (Al2O3, SiO2, and TiO2) composite membranes are fabricated for vanadium redox flow battery (VRFB) application. The composite membranes with 5 wt% of Al2O3, SiO2, and TiO2 (S/A-5 %, S/S-5 %, and S/T-5 %) exhibit excellent cell performance in VRFB. Incorporation of nano oxides (Al2O3, SiO2, and TiO2) in SPEEK membrane improves in aspect of thermal, mechanical, and chemical stabilities due to the hydrogen bonds’ interaction between SPEEK matrix and nano oxides. The energy efficiencies (EEs) of composite membranes are higher than that of Nafion 117 membrane, owing to the good balance between proton conductivity and vanadium ion permeability. The discharge–capacity retentions of composite membranes also overwhelm that of Nafion 117 membrane after 200 cycles, indicating their good stability in VRFB system. These low-cost SPEEK/nano oxide composite membranes exhibit great potential for the application in VRFB.  相似文献   

2.
Antimony phosphate nanoribbons was synthesized and characterized using different techniques. Studies showed that the synthesized antimony phosphate possessed highly crystalline monoclinic SbPO4 phase with an average crystallite size of 14 nm. TEM studies showed that antimony phosphate was present both as nano ribbons and nano particles. It is observed that the nano ribbons have length in the range of 500–700 nm and width around 100–200 nm whereas the nanoparticles size in the range of 1–5 nm. The synthesized nano phosphate was studied for its efficiency as sorbent for uptake of various metal ions including uranyl ion. The results indicated that a clean separation of uranyl ion from its various binary mixtures could be achieved at optimized pH of 4.5 and equilibration period of 1 h using 0.1 g of the sorbent.  相似文献   

3.
In this paper, we demonstrate the development of plasmonically active PMMA optical fiber probes by the attachment of gold nanoparticles to the probe surface functionalized by means of flowing post-discharges from dielectric barrier discharge (DBD) plasmas for the first time. Polymer optical fiber (POF) probes (U shape to improve absorbance sensitivity) were subjected to reactive gas atmospheres in the post-discharge region of a coaxial DBD plasma reactor run at atmospheric pressure in different gases (Ar, Ar + 10 % O2, O2, N2, N2 + 0.5 % H2). Plasma treatments in Ar or N2 gave rise to water-stable electrophilic functional groups on PMMA surface, whereas the amine groups generated by N2-containing plasmas were not stable. Subsequently, PMMA surfaces were treated with hexamethylene diamine (HMDA) to obtain stable amine groups through the reaction of electrophilic groups. Gold nanoflowers (AuNF, 37 nm, peak 570 nm) binding to the amine functionalized fiber probes was monitored in real-time by recording the optical absorbance changes at 570 nm with the help of a UV–vis spectrometer. Absorbance response from Ar or N2 plasma treated probes are 100 and 60 times, respectively, that of untreated control probes. A 25 fold improvement in absorbance response was obtained for Ar plasma treated POF in comparison with only HMDA treated POF. The shelf life of the hence fabricated plasmonically active probes was found to be at least 3 months. In addition, plasmonic activity of U-bent fiber probes treated in Ar plasma is better than the conventional wet-chemical activation by environmentally hazardous acid pre-treatment approaches.  相似文献   

4.
A simple, environmentally benign and energy efficient process for fabricating single faced superhydrophilic/hydrophobic cotton fabrics by controlling surface texture and chemistry at the nano/microscale is reported here. Stable ultra-hydrophobic surfaces with advancing and receding water droplet contact angles in excess of 146° as well as extreme superhydrophilic surfaces are obtained. Hydrophobic water-repellent cotton fabrics were obtained following plasma treatment through diamond-like carbon (DLC) coating by plasma enhanced chemical vapour deposition. The influence of changing different precursor’s plasma pre-treatments such as H2, Ar or O2 on the properties of DLC coatings is also evaluated using atomic force microscopy, X-ray photoelectron spectroscopy, attenuated total reflection Fourier transform infrared spectroscopy, and analysed in terms of contact angle measurements. Because of the DLC coating, the coated fabric showed to endure its superhydrophobic character even after 12 months.  相似文献   

5.
Sol–gel method was employed to prepare Ni–Co/Al2O3–MgO–ZrO2 nanocatalyst with various loadings of MgO (5, 10 and 25 wt%) for dry reforming of methane. The physiochemical properties of nanocatalysts were characterized by XRD, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), BET and fourier transform infrared spectroscopy (FTIR) analysis. Evaluation of catalytic performance was conducted in atmospheric pressure, stoichiometric feed ratio, GHSV of 24 l/gcat h and temperature range from 550 to 850 °C. XRD patterns represented that as MgO content increases, the amorphous behavior slightly intensifies and also dispersion of active phase improves which probably caused by strong metal–support interaction. Furthermore, FESEM analysis confirmed that all of prepared samples are nano scale. EDX results besides verifying the declared claim about the dispersion of samples proved the presence and detected the position of the various elements. In addition, based on the FESEM analysis, narrow particle size distribution, uniform morphology and dispersion without agglomeration were found for Ni–Co/Al2O3–MgO–ZrO2 with 25 wt% MgO. Moreover, smallest average particle size 11.6 nm (close to the critical size for Ni–Co catalyst to avoid carbon formation) was obtained for this nanocatalyst. Also, according to the BET analysis, MgO rich nanocatalyst represented the higher surface area than the other ones. Based on the excellent characterizations, Ni–Co/Al2O3–MgO–ZrO2 with 25 wt% MgO exhibited the best products yield through all of the investigated temperature e.g. H2 = 96.9 % and CO = 97.1 % at 850 °C. Furthermore, this nanocatalyst demonstrated the stable yield with H2/CO close to unit during 1,440 min stability test.  相似文献   

6.
《Analytical letters》2012,45(11):1721-1734
Abstract

A novel approach to assemble an H2O2 amperometric biosensor was introduced. The biosensor was constructed by entrapping horseradish peroxidase (HRP) labeled nano‐scaled particulate gold (nano‐Au) (HRP‐nano‐Au electrostatic composite) in a new silica sol‐gel/alginate hybrid film using glassy carbon electrode as based electrode. This suggested strategy fully merged the merits of sol‐gel derived inorganic‐organic composite film and the nano‐Au intermediator. The silica sol‐gel/alginate hybrid material can improve the properties of conventional sol‐gel material and effectively prevent cracking of film. The entrapment of HRP in the form of HRP‐nano‐Au can not only factually prevent the leaking of enzyme out of the film but also provide a favorable microenvironment for HRP. With hydroquinone as an electron mediator, the proposed HRP electrode exhibited good catalytic activity for the reduction of H2O2. The parameters affecting both the qualities of sol‐gel/alginate hybrid film and the biosensor response were optimized. The biosensor exhibited high sensitivity of 0.40 Al mol?1 cm?2 for H2O2 over a wide linear range of concentration from 1.22×10?5 to 1.46×10?3 mol L?1, rapid response of <5 s and a detection limit of 0.61×10?6 mol L?1. The enzyme electrode has remarkable stability and retained 86% of its initial activity after 45 days of storage in 0.1 mol L?1 Tris‐HCl buffer solutions at pH 7.  相似文献   

7.
Novel 9-amino-3-substituted-1,2,3,4-acridin-1-one derivatives and 9,14-diamino-7-substituted-7,8-dihydroquinolino[2,3-a]acridine derivatives were synthesized by the condensation reaction of 5-substituted-1,3-cyclohexanedione with 2-aminobenzonitrile and substituted 2-aminobenzonitrile using p-toluenesulfonic acid, K2CO3, and Cu2Cl2 as catalysts. The structures of all compounds were characterized by elemental analysis, infrared, mass spectrometry, and 1H and 13C NMR spectra. The crystal and molecular structures of 6, 14-diamino-3,4,11,12-tetramethoxy-7-phenyl-7,8-dihydroquinolino[2,3-a]acridine 5a have been determined by single-crystal x-ray diffraction analysis. The crystal of compound 5a belongs to triclinic with space group P-1, a = 1.06168(15) nm, b = 1.16951(17) nm, c = 1.6020(2) nm, α = 71.380(3)°, β = 77.686(3)°, γ = 66.743(3)°, Z = 2, V = 1.7231(4) nm3, R 1 = 0.1060, and wR 2 = 0.2192.  相似文献   

8.
A novel technique in controlling the size of SiO2 nano‐particles in the preparation of Nafion/SiO2 composite membranes via in situ sol–gel method, as well as the effects of nano‐particle size on membrane properties and cell performance, is reported in this paper. Nafion/SiO2 composite membranes containing SiO2 nano‐particles with four different diameters (5 ± 0.5, 7 ± 0.5, 10 ± 1, and 15 ± 2 nm) are fabricated by altering the reactant concentrations during in situ sol–gel reaction. Sequentially, size effects of SiO2 nano‐particles on membrane properties and cell performance are investigated by SEM/EDAX, TEM, TGA, mechanical tensile, and single cell tests, etc. The results suggest that 10 nm is a critical diameter for SiO2 incorporated into Nafion matrix, exhibiting desirable physico‐chemical properties for operation at elevated temperature and low humidity. At 110°C and 59% RH, the output voltage of the cell equipped with Nafion/SiO2 (10 nm) obtains an output voltage of 0.625 V at 600 mA/cm2, which is 50 mV higher than that of unmodified Nafion. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

9.
A 1D coordination polymer, {[Zn(μ1,5-dca)2(PZA)2](PZA)2}n (1), has been synthesized and characterized by single-crystal X-ray crystallography. The coordination modes of the dicyanamide (dca) and the pyrazinamide (PZA) were inferred by IR spectroscopy. The complex was applied to organic electroluminescent (EL) devices as the emitting materials. The electroluminescent device of ITO/NPB (40 nm)/Zn polymer: CBP (30 nm) (30 nm)/BCP (15 nm)/Alq (30 nm)/LiF (1 nm)/Al (100 nm) was fabricated. The EL device emits cyan light originating from this complex with high brightness and efficiencies. For 1, a maximum luminance of 34.9 cd/A was achieved at 9 V.  相似文献   

10.
Nanocrystalline manganese oxide was prepared and characterized using various techniques like XRD, surface area analyzer and zeta potential measurements. The sorption characteristics with respect to uptake of various ions including uranyl have been evaluated. Various experimental conditions which affect the sorption characteristics have been studied. Nanocrystalline manganese oxide was prepared by the hydrolysis of KMnO4 and the nano oxide were found to have a size of 8 nm and surface area of 145 m2/g. Due to the high surface area, the sorption property of the nano oxide was good. It was found that the sorption was achieved at different pH values and with varying time of equilibration. Thus it is seen that the kinetics was an important aspect for the possible separation of metal ions.  相似文献   

11.
Via chemical adsorption, various films were assembled onto silicon surfaces. The structures and properties of the monolayer‐ or bilayer‐modified silicon surfaces, such as Si‐C10H20 CH2OC(O)CF3, Si‐C10H20CH2OH, and Si‐C10H20‐CH2‐NH‐C18H37, were investigated by various techniques. x‐ray photoelectron spectroscopy (XPS) gave clear proofs of the formation of octadecylamine layer and other kinds of layers on silicon surfaces. The contact angle measurements showed that the wettability of silicon surfaces was dominated by the terminal functional groups of the attached layers. Atomic force microscopy (AFM) observations showed that interesting patterns have formed on the monolayer‐ or bilayer‐modified silicon surfaces. Electrochemical impedance spectra (EIS) measurements showed that the Si‐C10H20CH2‐NH‐C18H37 has a better ability to prevent charge transfer as compared with that of Si‐C10H20CH2OH, which may find applications in the area of surface passivations.  相似文献   

12.
Non-thermal atmospheric pressure plasma jet could generate various kinds of radicals on biosolution surfaces as well as inside the biosolutions. The electron temperature and ion density for this non-thermal plasma jet have been measured to be about 0.8~1.0 eV and 1 × 1013 cm?3 in this experiment, respectively, by atmospheric pressure collisional radiative model and ion collector current. In this context, the hydroxyl OH radical density inside the biosolutions has been also investigated experimentally by ultraviolet absorption spectroscopy when the Ar non-thermal plasma jet has been bombarded onto them. It is found that the emission and absorption profiles for the other reactive oxygen species such as NO (226 nm) and O2*? (245 nm) are shown to be very small inside the biosolution in comparison with those for the OH radical species. It is found that the densities of OH radical species inside the biosolutions are higher than those on the surface in this experiment. The densities of the OH radical species inside the deionized water, Dulbecco’s modified eagle medium, and phosphate buffered saline are measured to be about 2.1 × 1016, 1.1 × 1016, and 1.0 × 1016 cm?3, respectively, at 2 mm downstream from the surface under optimized Ar gas flow of 200 sccm. It is also found that the critical hydroxyl OH radical density for the lung cancer H460 cells to experience an apoptosis is observed to be around 0.3 × 1016 cm?3 under 1 min plasma exposure in this experiment.  相似文献   

13.
A series of azo-ester linked mesogen containing liquid crystalline acrylate compounds C1-C6 having different terminal groups (–F, –Cl, –Br, –OCH3, –OC2H5 and –OC3H7) were successfully synthesised and characterised. The chemical structure, purity, thermal stability, mesophase behaviour and optical property of the synthesised compounds were investigated by different instrumental techniques. X-ray crystal structure showed that compounds C1, C4 and C5 exhibited more stable E configuration with two bulky group in the opposite side of the N=N double bond motifs. The fluoro-substituted derivative (C1) is connected by the R12(5) type of C–H…O hydrogen bond motifs whereas the molecules of C4, and C5 are connected to each other by means cyclic R22(8) type of C–H…O hydrogen bond motifs. Thermogravimetric study revealed that the investigated compounds exhibited excellent thermal stability. All the compounds showed enantiotropic liquid crystal (LC) phase behaviour and the mesophase formation was greatly influenced by the terminal substituents. Alkoxy (–OCH3, –OC2H5 and –OC3H7) substituted compounds exhibited greater mesophase stability than those of halogen (–F, –Cl and –Br) terminated derivatives. UV-vis spectroscopic study revealed that the investigated compounds exhibited a broad absorption band around 300–420 nm with absorption maximum (λmax) of nearly 370 nm.  相似文献   

14.
By means of the hybrid exchange–correlation functionals, as it is implemented in the CRYSTAL computer code, ab initio calculations for main ABO3 perovskite (0 0 1) surfaces, namely SrTiO3, BaTiO3, PbTiO3, CaTiO3, SrZrO3, BaZrO3, PbZrO3 and CaZrO3, were performed. For ABO3 perovskite (0 0 1) surfaces, with a few exceptions, all atoms of the upper surface layer relax inward, all atoms of the second surface layer relax outward, and all third layer atoms, again, inward. The relaxation of (0 0 1) surface metal atoms for ABO3 perovskite upper two surface layers for both AO and BO2-terminations, in most cases, are considerably larger than that of oxygen atoms, what leads to a considerable rumpling of the outermost plane. The ABO3 perovskite (0 0 1) surface energies always are smaller than the (0 1 1) and especially (1 1 1) surface energies. The ABO3 perovskite AO and BO2-terminated (0 0 1) surface band gaps always are reduced with respect to the bulk values. The B–O chemical bond population in ABO3 perovskite bulk always are smaller than near the (0 0 1) and especially (0 1 1) surfaces.  相似文献   

15.
In this paper, we fabricate two kinds of anodic aluminum oxide (AAO) films with controllable nanopore size by changing electrolytes and electrolytic parameters. The first AAO film with a four-layer structure was fabricated by sequential anodization of aluminum in aqueous solution of H2SO4, H2C2O4, malonic acid, and tartaric acid at different anodic oxidation voltages. The average pore diameter of the as-prepared AAO film is 25 nm in the first layer, 54 nm in the second layer, 68 nm in the third layer, and 88 nm in the fourth layer, respectively. The pore densities of each layer decrease downwards to Al substrate, which are 300?×?108, 100?×?108, 21?×?108, and 6.9?×?108 cm?2, respectively. Furthermore, another AAO film with periodically changed pore diameter was fabricated by alternating anodization of aluminum in aqueous solution of H3PO4 and tartaric acid under galvanostatic mode. The anodization processes present approximately identical best ordering voltage (195 V) in H3PO4 and tartaric acid under galvanostatic mode. The pore diameter with periodic change can be enlarged through a pore-widening treatment. Both AAO films with special nanopore structures can be used not only as templates for preparing nano-array materials whose pore diameter presents periodic change or gradual increase, but also as nanofilters to separate materials in some special media.  相似文献   

16.
Nanocrystalline perovskite oxide materials ABO3 (where A = Ba, Ca, Mg, Sr; and B = Ce, Mn, and Ti) have been synthesized via sol-citrate combustion and hydrothermal-based methods with and without surfactant under mild conditions. Metal-titanates (ATiO3) were prepared using synthesized anatase-TiO2 nanotube powder, metal hydroxide/chloride solutions, and NaOH as raw materials. The stoichiometric amount of all reactants were put in polytetrafluoroethylene (PTFE)-lined stainless steel digestion reactor and were kept in convention oven at desired reaction conditions like mole composition, pH, temperature, and time, in range A/Ti = 0.9–1.1, 10–12, 150–170 °C for 24–48 h, respectively. The nanocrystalline barium cerium oxide (BaCeO3) was synthesized using citric acid as polymerization agent in sol-combustion process, whereas barium manganite (BaMnO3) was prepared via hydrothermal process using polyethyl glycol surfactant as structure directing agent. Thermal stability, phase evolution, and morphology of synthesized products were characterized by thermogravimetry and differential thermal analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM). XRD results revealed that synthesized CaTiO3 and BaMnO3 nanorods had an orthorhombic perovskite and hexagonal structure, respectively; whereas, the nanoparticle morphologies of BaTiO3, Ba0.5Sr0.5TiO3, and MgTiO3, BaCeO3 perovskite oxides were found strongly depended on pH of the precursor solutions. SEM images showed variety of morphological structures ranging from nanostructured surface with distinct particles morphology to nanowires and nanorods (length varies from nano to several micrometers) and uniform diameter ~<100 nm, depending upon the hydrothermal reaction conditions.  相似文献   

17.
Two new pentaborates [M(dap)3][B5O6(OH)4]2·H2O (M = Co (1) and Ni (2); dap = 1,2-diaminopropane) have been hydrothermally synthesized. Both structures were determined by single crystal X-ray diffraction and further characterized by elemental analysis, FT-IR, thermogravimetric analysis and photoluminescence spectroscopy. Two compounds are isostructural and consist of isolated pentaborate [B5O6(OH)4]? anions and [M(dap)3]2+ complex cations. The anionic [B5O6(OH)4]? groups are linked by extensive hydrogen bonds to form a 3-D supramolecular framework with large channels, in which the transition-metal complex templates are located. The luminescent properties of 1 and 2 were studied, and blue luminescence occurs with an emission maximum at 405 and 408 nm upon excitation at 332 and 328 nm respectively. Crystal data: 1, monoclinic, space group P21/c (No. 14), a = 9.7159(5) Å, b = 29.3372(19) Å, c = 11.5121(6) Å, β = 103.286(5)°, V = 3193.6(3) Å3, Z = 4; 2, monoclinic, space group P21/c, a = 9.7264(4) Å, b = 29.3810(16) Å, c = 11.5185(6) Å, β = 103.249(4)°, V = 3204.0(3) Å3, Z = 4.  相似文献   

18.
Nanoparticles of two molecule-based conductors, namely TTF·TCNQ and TTF[Ni(dmit)2]2, have been prepared in organic solution in the presence of ionic or nonionic species bearing a long-chain alkyl group, acting as growth-controlling agents. The size, morphology, and state of dispersion of the nanoparticles depended on the nature of the growth-controlling agent and the reaction temperature. In the presence of a long-chain alkyl-based ionic liquid at ?50 °C, electron micrographs evidence that TTF·TCNQ nano-objects are frequently elongated, whereas TTF[Ni(dmit)2]2 nanoparticles are aggregated. In the presence of a neutral long-chain alkyl-based imine at room temperature, nanoparticles are spherical (mean diameter <20 nm) and well dispersed. Vibration spectra evidence that the amounts of charge transfer for TTF·TCNQ and TTF[Ni(dmit)2]2 as nano-objects are very similar to those for the same phases as bulk materials. According to the thermoanalytical investigations, the prepared nanoparticles are stable thermally up to approximately 200 °C, and their decomposition is generally a multi-step process. Their heat treatment results in various sulfur-containing volatiles (CS2, SO2, H2S); moreover, HCN is also detected in the case of nitrogen-containing molecules (TCNQ).  相似文献   

19.
Thermal plasma processes have been investigated by optical emission spectroscopy during the synthesis of TiBx nanoparticles from TiO2, B and C precursors using argon and helium both as plasma and sheath gases. Line-rich emission spectra were observed both in Ar–He–TiO2–B and Ar–He–TiO2–B–C cases. Emissions detected in the spectral region of 300–1000 nm were attributed to the electronic relaxation of excited Ti(I) and ionic fragments Ti(II), as well as the molecular species of TiO. The plasma temperature was calculated from the vibration–rotation temperature of the A–X electronic transition of TiO molecule by the least-squares fitting of experimental data to theoretical spectra. The temperatures at 100 mm downstream the torch outlet were found to be between 3800 and 2700 K for the Ar–He–TiO2–B system, and between 5100 and 4300 K for the Ar–He–TiO2–B–C system, respectively. The morphology of as-formed nanoparticles was characterized by transmission electron microscopy. Measurements of specific surface area, evaluated on the basis of Brunauer, Emmett and Teller equation, revealed that in all experimental setups titanium boride nanoparticles were formed with a mean particle size of 17–85 nm. On the basis of X-ray diffraction patterns, the solid reaction products were composed of TiB2, boron doped titanium indicated as Ti(B), Ti2O3, H3BO3 and TiC. The actual composition of products depended on the synthesis conditions.  相似文献   

20.
Powders of the Nasicon material NaTi2(PO4)3 were directly synthesized at ultra-low temperature. NaTi2(PO4)3 was obtained by mixing the initial reagents titanium hydroxide, 85 % H3PO4, and NaH2PO4·2H2O at 85 °C for 3.5 h or at 125 °C for 1.5 h. The raw materials and synthesized products were characterized for purity, crystal structure, particle size, and powder morphology by thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy, scanning electron microscopy (SEM), and UV–visible diffuse reflectance spectroscopy. XRD results revealed that NaTi2(PO4)3 powders with rhombohedral crystal structure were synthesized at 85 and 125 °C. SEM patterns showed that the as-prepared products were agglomerated and that each of the agglomerations consisted of many small grains 50–80 nm in diameter.  相似文献   

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