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ABSTRACT: Amine-functionalized SBA-15 with uniform morphology and well-defined mesostructure was prepared using a postgrafting route. The morphology, mesostructure, and functionality of the materials were characterized by scanning electron microscopy, transmission electron microscopy, small-angle X-ray scattering, nitrogen adsorption-desorption, Fourier transform infrared spectroscopy, and solid-state nuclear magnetic resonance spectroscopy techniques. The results show that hexagonal lamelliform SBA-15 with a uniform particle size and short vertical channels plays two significant roles in uniformly dispersing amine-functionalizing groups and effectively adjusting the loadings of the functional groups within the mesopore channels. To confirm the potential application of the hybrids in gas sensors, using amine-functionalized SBA-15 as a sensing material and a quartz crystal microbalance as a transducer, a parts per billion level formaldehyde sensor with high sensitivity (response time about 11 s, recovery time about 15 s) and good chemoselectivity was achieved. This material holds great potential in the area of rapid, sensitive, and highly convenient formaldehyde detection.
Langmuir 05/2012; 28(20):7843-50. · 4.19 Impact Factor
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ABSTRACT: Ferrocene (Fc) was encapsulated in the cavities of a NaY zeolite by vapor diffusion via sublimation at below 100°C. The resulting
Fc@NaY zeolite composite was investigated by power X-ray diffraction, diffuse reflectance UV–vis and FT-IR spectroscopy, and
by cyclic voltammetry. The results indicated that Fc was encapsulated into the zeolite whose microporous structure had remained
intact. The Fc in the silica matrix had retained its electroactivity and did not leach out. A glucose biosensor was obtained
by immobilization of the modified zeolite and glucose oxidase on a carbon paste electrode. It displays a linear response to
glucose (from 0.8μM to 4.0mM), a detection limit of 0.2μM, and a response time of 4s. The good performance of the biosensor
is ascribed to the biocompatibility of the zeolite and presence of Fc which facilitates the electron transfer from the enzyme
to the surface of the electrode.
FigureReagentless glucose biosensor is constructed by immobilization of glucose oxidase on a ferrocene@NaY zeolite composite. The
biosensor displays very good responses to the different concentrations of glucose.
KeywordsNaY zeolite–Ferrocene–Glucose oxidase–Amperometric biosensor
Microchimica Acta 04/2012; 174(3):281-288. · 3.03 Impact Factor
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ABSTRACT: A sonochemical method is developed to fabricate SnO2 nanotubular materials from biological substances (here, it is cotton). The cotton fibers in SnCl2 solution were first treated with ultrasonic waves in air, followed by calcinations to give nanotubular materials that faithfully
retain the initial cotton morphology. The microstructure and morphology of the obtained SnO2 nanotubules were characterized by the combination of field-emission scanning electron microscope (FE-SEM), transmission electron
microscopy (TEM), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and N2 adsorption/desorption measurements. The thermal behavior and crystalline properties were examined in the temperature range
of 450–700°C. The nanocrystals composing of SnO2 nanotubules were estimated about 8.5, 13.2, and 14.2nm corresponding to calcination temperatures of 450, 550, and 700°C,
respectively. The sensor performance of biomorphic SnO2 nanotubules calcined at 700°C was investigated in the atmosphere of ethanol, formaldehyde, carbinol, carbon monoxide, hydrogen,
ammonia, and acetone, respectively, which exhibited a good selectivity for acetone at a working temperature of 350°C. The
sensitivity to 20ppm acetone, S, was 6.4 at 350°C with rapid response and recovery (around 10–9s). These behaviors were well explained in relation to the
morphology of the nanotubules thus produced.
KeywordsSnO2
-Nanotubular-Sonochemical method-Gas sensor-Nanomanufacturing
Journal of Nanoparticle Research 04/2012; 12(4):1389-1400. · 3.29 Impact Factor
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ABSTRACT: The aim of the present study was to evaluate the effect of pluronic P123 (P123) and pluronic F127 (F127) on intestinal P-glycoprotein (P-gp) and cytochrome P450 3A using the specific substrates rhodamine-123 (R-123) and midazolam, respectively. Caco-2 cells and everted gut sacs were used as models of intestinal mucosa to assess intestinal absorption of R-123, while rat intestinal microsomes were utilized to examine the effect of P123 and F127 on in vitro midazolam metabolism. P123 and F127 were observed to increase the intracellular accumulation of R-123 in Caco-2 cells in a dose-dependent manner. P123 significantly lowered the efflux ratio of R-123 at two concentrations in Caco-2 monolayers, whereas F127 lowered the efflux ratio only at 1%. Moreover, both pluronics markedly enhanced mucosal to serosal absorption of R-123 in excised ileum of rats. However, no significant difference in relative enzyme activity were observed between P123- or F127-treated and control groups, regardless of the concentrations of P123 and F127 studied. Collectively, these results obtained from the present study demonstrated that P123 and F127 were capable of inhibiting the intestinal P-gp activity, but had little or no effect on intestinal cytochrome P450 3A activity, indicating that P123 and F127 can potentially be used as pharmaceutical ingredients to improve the oral bioavailability of coadministered P-gp substrates via P-gp efflux pump inhibition.
Archives of Pharmacal Research 10/2011; 34(10):1719-28. · 1.59 Impact Factor
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ABSTRACT: Copper(I) bromide (CuBr) was considered to be a good gas sensing material with a high sensitivity and selectivity to ammonia (NH3) at ambient temperature. The NH3 sensing mechanism was generally considered to be a result of the strong interaction between NH3 molecules and Cu+ ions. When CuBr-coated quartz-crystal microbalance (QCM), a typical gravimetric transducer, was exposed to NH3, the device displayed a decrease rather than an increase in total mass. This was an unusual phenomenon. In situ diffuse reflectance infrared Fourier transform spectrometry (DRIFTS) was employed to examine the reasons of this total mass decrease. Probing of species formed on the CuBr surface revealed that a complex form between the Cu+ ions and the O2 molecules in air existed. Consequently, O2 gas with a higher molecular weight than NH3 was substituted by NH3 gas, inducing the decrease in mass. The band at 1123 cm−1 of the DRIFT spectrum of CuBr corresponding to the complex formed between O2 molecules and Cu+ ions was identified. The intensity of this band which decreased with the formation of NH3 complex was also observed. The observation was a result of the substitution process for O2 adsorption instead of NH3.
01/2011;
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ABSTRACT: We reported a novel graphitized carbon coated Pt composite synthesized by one-pot TEOS polymerization-high temperature carbonation approach. Electrochemical measurements display that the obtained Pt/graphitized carbon (Pt@GC) shows high electrochemical activity toward hydrogen oxidation. Additionally, quartz crystal microbalance results for hydrogen adsorption indicate that Pt@GC has high performance of hydrogen storage. The synthesized Pt@GC composite shows significant potential applications in H2/O2 (air) fuel cell and hydrogen storage.
Integrated Ferroelectrics 01/2011; 129(1):133-138. · 0.30 Impact Factor
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ABSTRACT: Pt nanoparticles were introduced on the surface of ZnO nanowires using a chemically driven self-assembly method. Through this controllable method, Pt-nanoparticle-functionalized ZnO nanowires (Pt NPs-ZnO NWs) with uniform particle dispersion, tunable Pt particle sizes, and narrow particle size distribution were obtained. Changes in the morphology of the decorative preparation were observed as the amount of linker reagent and the concentration of Pt nanoparticle solution were altered. The as-prepared Pt NPs-ZnO NWs with optimal morphology showed excellent gas sensing and photocatalytic performance. Tuning of the functionalities of photocatalytic and gas sensors can be obtained by tailoring the morphology of Pt NP-ZnO NW composite materials.
Nanotechnology 07/2010; 21(28):285501. · 3.98 Impact Factor
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ABSTRACT: SnO(2) nanowires with an average 0.6 microm in length and about 25 nm in diameter were prepared by a hydrothermal method. The sensors were fabricated using SnO(2) nanowires assembled with Pd nanocrystals. The sensing properties of the sensors such as selectivity, response-recovery time and stability were tested at 290 degrees C. After assembling Pd nanocrystals onto the surface of SnO(2) nanowires, the gas sensing properties of the sensors toward H(2)S were improved. The sensors based on Pd nanoparticle@SnO(2) nanowires exhibit high stability owing to stable single crystal structure. The mechanism of promoting sensing properties with Pd nanoparticles is discussed.
Talanta 07/2010; 82(2):458-63. · 3.79 Impact Factor
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ABSTRACT: An ordered mesoporous carbon material functionalized with carboxylic acid groups was synthesized. It was characterized by powder X-ray diffraction, transmission electron microscopy, Fourier transform IR spectroscopy and N(2) adsorption/desorption. Furthermore, this material was used to modify an electrode surface combined with a hydrophobic ionic liquid. The functionalized ordered mesoporous carbon/ionic liquid gel modified electrode shows excellent electrocatalytic performances for the oxidation of dopamine, uric acid and ascorbic acid. The presence of the ionic liquid promotes the electron transfer. Linear responses for dopamine and uric acid were obtained in the ranges of 0.1 to 500 μM and from 0.1 to 100 μM with detection limits of 4.1 and 2.5 nM (signal-to-noise ratio of 3), respectively, under optimum conditions. A quick and sensitive biosensor based on functionalized ordered mesoporous carbon and an ionic liquid has been developed for the first time for the detection of dopamine and uric acid in the presence of a large amount of ascorbic acid.
Analytical and Bioanalytical Chemistry 03/2010; 396(5):1755-62. · 3.78 Impact Factor
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ABSTRACT: The ferrocene/NaY zeolite composites (Fc/NaY) are introduced on the surface of a glassy carbon electrode together with the hydrophobic ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6). The modified electrode thus constructed exhibits a pair of reversible redox peaks corresponding to ferrocene. Additionally the peak separation remains almost constant (58–75 mV) and the value of the ratio ipa/ipc is close to 1 for scan rates in the range from 10 to 1000 mV s−1. The effects of the scan rate, aqueous supporting electrolytes, hydrophobic ionic liquid and the contents of ferrocene encapsulated by electrochemistry are investigated. The extrazeolite electron transfer process is discussed. Furthermore, the Fc/NaY/IL-modified electrode shows good mediation towards oxidation of ascorbic acid, dopamine, hydroquinone, and catechol.
Electroanalysis 11/2009; 21(23):2597 - 2601. · 2.87 Impact Factor
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ABSTRACT: The nanocomposite with polypyrrole (PPy) confined in ordered mesoporous silica SBA-15 channels was synthesized by in situ electropolymerization. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N2 adsorption/desorption, and FT-IR studies indicated that the nanocomposite has the well-ordered hexagonal structures and PPy was in situ polymerized into the channels instead of the outer surface of SBA-15. Furthermore, the PPy/SBA-15 nanocomposite was used as an electrode modifier. We found that the nanocomposite-modified electrode exhibited good electrocatalytic activities for hydroquinone oxidation where PPy chains could facilitate the electron transfer between molecular sieves and electrode surface. Three dihydroxybenzene isomers (hydroquinone, catechol and resorcinol) have been successfully detected at PPy/SBA-15 modified electrode by preconcentration of the analyte.
Electroanalysis 06/2009; 21(16):1792 - 1798. · 2.87 Impact Factor
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ABSTRACT: In this work, mesoporous In2O3 nanorods composed of many small well-aligned crystal nanostructures have been fabricated by a simple sol−gel process, with block copolymer PE6800 as a soft template controlling their morphology. The effects of the experimental parameters such as the concentration of PE6800, the dosage of InCl3·4H2O, reaction temperature, and pH values were investigated by a series of experiments. The as-synthesized mesoporous In2O3 nanorods showed excellent gas-sensing properties to C2H5OH in terms of sensor response and selectivity.
05/2009;
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ABSTRACT: Brush-like hierarchical ZnO nanostructures assembled from initial 1D ZnO nanostructures were prepared from sequential nucleation and growth following a hydrothermal process. The morphology, structure, and optical property of hierarchical ZnO nanostructures were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and photoluminescence (PL) studies. The FE-SEM images showed that the brush-like hierarchical ZnO nanostructures are composed of 6-fold nanorod-arrays grown on the side surface of core nanowires. Compared with ZnO nanowires, brush-like hierarchical ZnO nanostructures easily fabricated satisfactory ethanol sensors. The main advantages of these sensors are featured in excellent selectivity, fast response (less than 10 s), high response (sensitivity), and low detection limit (with detectable ethanol concentration in ppm).
02/2009;
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ABSTRACT: The bamboo-shaped nitrogen-doped carbon nanotubes (CNx) with different nitrogen content were synthesized using Fe-containing SBA-15 molecular sieve as catalyst with thermal decomposition. The CNx nanotubes prepared were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD) and Raman spectroscopy. The results suggest that there are a larger amount of defective sites on CNx nanotubes surfaces due to the nitrogen doping and CNx nanotube with higher nitrogen content possesses lower graphitic ordering in the framework. Furthermore the effects of nitrogen content on the electrochemistry of CNx modified electrodes were investigated by cyclic voltammetry (CV). CNx modified electrodes exhibit better electrocatalytic activities to the oxidation of hydroquinone. Moreover CNx with lower nitrogen content is in favor of the electron transfer between dihydroxybenzene and electrode surface, while CNx with higher nitrogen content possesses high surface adsorptive ability. CNx modified electrodes can be applied to determine dihydroxybenzene isomers directly and simultaneously by linear sweep voltammetry technique without previous separation.
Electroanalysis 08/2008; 20(18):1981 - 1986. · 2.87 Impact Factor
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ABSTRACT: Square-shaped single-crystalline SnO(2) nanowires and their sphere-like hierarchical structures were synthesized successfully with a template-free hydrothermal approach. It was found that an intermediate phase-Na(2)Sn(OH)(6)-is first produced because it is slow to dissolve in ethanol/water media. The intermediate phase gradually decomposes and converts into SnO(2) at temperatures higher than 200 °C. The reaction temperature also affects the microstructure of SnO(2) nanomaterials. Uniform square-shaped SnO(2) nanowires, which form sphere-like hierarchical structures in 100% structure yield, can be produced at 285 °C on a large scale. The diameter of the nanowires shows a decrease accompanying the increase of the reaction temperature. The temperature effect could be a result of the faster and oriented growth of SnO(2) nanowires along their [Formula: see text] direction at higher temperature. Chemical sensors constructed with square-shaped SnO(2) nanowires exhibit excellent stability, good sensitivity and selectivity, as well as a quick response and short recovery times under exposure to acetone gas in practical applications.
Nanotechnology 05/2008; 19(18):185705. · 3.98 Impact Factor
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ABSTRACT: Ordered mesoporous carbon (OMC) supported nanosized Pt and PtCo alloy electrocatalysts were synthesized by ethylene glycol hydrothermal reduction route and their electrochemical oxidation activity toward several typical small organic molecules (SOMs) was investigated. Structural characterization revealed that Pt and PtCo nanoparticles with mean diameter of 3–4 nm were well dispersed on OMC (BET specific surface of 2220 cm2/g). Electrochemical measurements confirmed that electrochemical oxidation behaviors of SOMs on synthesized Pt/OMC and PtCo/OMC catalysts were complicated and the carbon chain length of SOMs and the intermediates, especially COads oxidation behaviors on Pt active sites are two main factors which affect the SOMs oxidation.Highlights► Ordered mesoporous carbon supported Pt and PtCo bimetal composites were synthesized. ► Electrochemical oxidation activity toward small organic molecules were investigated. ► Electro-oxidation is related to the chain length of SOMs and their intermediates.
International Journal of Hydrogen Energy 36(16):9551-9561. · 4.05 Impact Factor
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ABSTRACT: Single-crystal, metastable, hexagonal In2O3(H-In2O3) nanorods were synthesized by annealing InOOH nanorods (prepared by solvothermal method) at 600 °C under ambient pressure. The samples are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and their gas sensitivities are detected. The gas sensitivity results show that hexagonal In2O3 nanorods are very sensitive to dilute ethanol vapor.
Materials Letters. 62:1363-1365.
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ABSTRACT: A novel mesoporous silica SBA-15 with monodisperse hexagonal lamelliform was prepared, and deposited on the quartz crystal microbalances (QCMs) to construct highly stable and sensitive humidity sensors. The humidity sensing characteristics of the sensors were investigated by measuring the resonant frequency shift of QCMs due to the additional mass loading caused by adsorption of water. X-ray diffraction, nitrogen adsorption/desorption, transmission electron microscopy and field emission scanning electron microscopy were employed to characterize these sensing materials. The results showed that the sensors had high sensitivity, good stability, short response/recovery time, well reproducibility and narrow hysteresis. Herein, not only a novel and low-cost humidity sensor material was exploited, but also a new application area for mesoporous materials was opened up.
Sensors and Actuators B: Chemical.
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ABSTRACT: Pure ZnO powder was made by chemical precipitation. ZnO-based gas sensing materials and Al2O3-based catalysts doped with a noble metal were prepared with impregnation. Gas sensitivity of ZnO single layer and double layer film gas sensors was measured in static state. It can be shown from experimental results that the gas sensitivity and selectivity of ZnO gas sensor can be improved by doping noble metal and using noble metal catalyst coating.
Sensors and Actuators B Chemical 66:161-163. · 3.90 Impact Factor
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ABSTRACT: The LiV3O8 samples with different morphologies have been successfully prepared by a mixed hydrothermal–sol–solid-state route via the reaction of vanadium pentoxide(V2O5) and lithium hydrate(LiOH) at 200 °C in basic medium and subsequent gelation at 100 °C and thermal treatment at 300–550 °C. The crystal structure and morphology of the samples were characterized by X-ray diffraction (XRD), specific surface area measurements and scanning electron microscopy (SEM). Their electrochemical properties were investigated by means of constant charge/discharge cycling measurement. The results indicated that the calcination temperature has a significant effect on the crystal structure, morphology, and specific surface area of the LiV3O8 samples, which consequently affects their electrochemical performance such as the initial capacity and the cycleability. The sample heat-treated at 300 °C shows the morphology of irregular blocks with low degree of crystallinity and high specific surface area, exhibiting high initial discharge capacity of 277.7 mAh g−1 but a fast capacity fade. In contrast, the samples annealed at higher temperature with perfectly uniform rod-like morphology show much better cycle performance.
Journal of Alloys and Compounds 467:327-331. · 2.29 Impact Factor
