Zi-Ling Xue

Imprint Coating: A Novel Synthesis of Selective Functionalized Ordered Mesoporous Sorbents

Molecular imprinting of surfaces of mesoporous sorbents is a novel method for introducing template-selective recognition sites. This method makes use of the unique surface environment of hexagonally packed mesopore surfaces of selected pore sizes (see the schematic representation) and coats such surfaces with functional ligands by binding to a metal ion template.

BiOBr hierarchical microspheres: Microwave-assisted solvothermal synthesis, strong adsorption and excellent photocatalytic properties.

Two kinds of BiOBr nanosheets-assembled microspheres were successfully prepared via a facile, rapid and reliable microwave-assisted solvothermal route, employing Bi(NO(3))(3)·5H(2)O and cetyltrimethylammonium bromide (CTAB) as starting reagents in the absence or presence of oleic acid. The phase and morphology of the products were characterized by powder X-ray diffraction (XRD), energy dispersive spectrometry (EDS), selected area electron diffraction (SAED), high resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM). Experiments indicated that the formation of these building blocks of microspheres could be ascribed to the self-assembly of nanoparticles according to mesocrystal growth mode. Interestingly, both samples exhibited not only strong adsorption abilities, but also excellent photocatalytic activities for methyl orange (MO), rhodamine B (RhB) and phenol. The resulting BiOBr hierarchical microspheres are very promising adsorbents and photocatalysts for the treatment of organic pollutants.

Focused ion beam induced deposition of platinum

Focused ion beam induced deposition of platinum from a precursor gas of (methylcyclopentadienyl)trimethyl platinum has been demonstrated. This organometallic compound is solid at room temperature with a vapor pressure of 0.054 Torr. Ga+ ions at 30–40 keV have been used. The resistivity and composition of the film and the deposition yield have been measured as a function of ion current density, line dose, substrate temperature, geometry, and supplemental hydrogen pressure. Yield varies from 0.2 to 34, and resistivity varies from 70 to 700 μΩ cm depending on the conditions. The resistivity and content of the carbon impurity are reduced as the ion current increases: the lowest resistivity is observed at the highest current density corresponding to 0.222 nA at scan speed 500 cm/s repeated over a 350 μm long line. The minimum linewidth achieved so far is 0.3 μm. Transmission electron microscopy shows the Pt film to be amorphous, and Auger analysis gives the film composition 46% Pt, 24% C, 28% Ga, and 2% O. The...

Persimmon-like (BiO)2CO3 microstructures: hydrothermal preparation, photocatalytic properties and their conversion into Bi2S3

We report here the preparation of self-assembled persimmon-like (BiO)2CO3 microstructures via a simple hydrothermal process. Powder X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), field emission scanning electron microscopy (FE-SEM), selected area electron diffraction (SAED) and high resolution transmission electron microscopy (HRTEM) were employed to characterize the phases and morphologies of the products. The reactants could greatly influence the phases and morphologies of the final products. The growth process of the persimmon-like (BiO)2CO3 microstructures has been investigated. The persimmon-like (BiO)2CO3 could be utilized as a sacrificial template to synthesize sphere-like Bi2S3 microstructures by a chemical transformation process. The as-prepared (BiO)2CO3 was able to efficiently degrade Rhodamine B (RhB) and eosin sodium salt under simulated solar irradiation.

Slow Magnetic Relaxation in a Mononuclear Eight-Coordinate Cobalt(II) Complex

The quest for the single-molecular magnets (SMMs) based on mononuclear transition-metal complexes is focused on the low-coordinate species. No transition-metal complex with a coordination number of eight has been shown to exhibit SMM properties. Here the magnetic studies have been carried out for a mononuclear, eight-coordinate cobalt(II)-12-crown-4 (12C4) complex [Co(II)(12C4)2](I3)2(12C4) (1) with a large axial zero-field splitting. Magnetic measurements show field-induced, slow magnetic relaxation under an applied field of 500 Oe at low temperature. The magnetic relaxation time τ was fitted by the Arrhenius model to afford an energy barrier of Ueff = 17.0 cm(-1) and a preexponential factor of τ0 = 1.5 × 10(-6) s. The work here presents the first example of the eight-coordinate, mononuclear, 3d metal complex exhibiting the slow magnetic relaxation.

Individual and simultaneous determination of lead, cadmium, and zinc by anodic stripping voltammetry at a bismuth bulk electrode.

A bismuth bulk electrode (BiBE) has been investigated as an alternative electrode for the anodic stripping voltammetric (ASV) analysis of Pb(II), Cd(II), and Zn(II). The BiBE, which is fabricated in-house, shows results comparable to those of similar analyses at other Bi-based electrodes. Metal accumulation is achieved by holding the electrode potential at -1.4V (vs. Ag/AgCl) for 180 s followed by a square wave voltammetric stripping scan from -1.4 to -0.35 V. Calibration plots are obtained for all three metals, individually and simultaneously, in the 10-100 microg L(-1) range, with a detection limit of 93, 54, and 396 ng L(-1) for Pb(II), Cd(II), Zn(II), respectively. A slight reduction in slope is observed for Cd(II) and Pb(II) when the three metals are calibrated simultaneously vs. individually. Comparing the sensitivities of the metals when calibrated individually vs. in a mixture reveals that Zn(II) is not affected by stripping in a mixture. However, Pb(II) and Cd(II) have decreasing sensitivities in a mixture. The optimized method has been successfully used to test contaminated river water by standard addition. The results demonstrate the ability of the BiBE as an alternative electrode material in heavy metal analysis.

Microwave-assisted solution-phase preparation of flower-like Bi2WO6 and its visible-light-driven photocatalytic properties

We report here the preparation of flower-like Bi2WO6via a simple, rapid, microwave-assisted solution-phase process. Powder X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), field emission scanning electron microscopy (FE-SEM) and high resolution transmission electron microscopy (HRTEM) were employed to characterize the phase and morphologies of the products. The time-dependent experiments showed an Ostwald ripening mechanism in the crystal growth process. The as-prepared Bi2WO6 was able to efficiently degrade Rhodamine B (RhB) under visible light irradiation. Calcination was found to decrease the photocatalytic performance of flower-like Bi2WO6.

Fabrication of nanocrystalline ZnWO4 with different morphologies and sizes via hydrothermal route

Abstract ZnWO 4 nanocrystals have been prepared via a hydrothermal route, and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy. The size and morphology of ZnWO 4 nanocrystals were found to depend on the reaction temperature and pH. The length of ZnWO 4 nanorod increased with the increase in pH of the hydrothermal solution. An unusual nanoparticle-to-nanorod transformation was observed during the formation of ZnWO 4 nanoparticles at pH 11.0 and 180 °C. Luminescent properties of ZnWO 4 nanocrystals were investigated by photoluminescence (PL) spectroscopy.

Fluorescent-Dye-Doped Sol−Gel Sensor for Highly Sensitive Carbon Dioxide Gas Detection below Atmospheric Concentrations

Optical fluorescence sol-gel sensors have been developed for the detection of carbon dioxide gas in the 0.03-30% range with a detection limit of 0.008% (or 80 ppm) and a quantitation limit of 0.02% (or 200 ppm) CO(2). Sol-gels were spin-coated on glass slides to create an organically modified silica-doped matrix with the 1-hydroxypyrene-3,6,8-trisulfonate (HPTS) fluorescent indicator. The luminescence intensity of the HPTS indicator (513 nm) is quenched by CO(2), which protonates the anionic form of HPTS. An ion pair technique was used to incorporate the lipophilic dye into the hydrophilic sol-gel matrix. TiO(2) particles (<5 microm diameter) were added to induce Mie scattering and increase the incident light interaction with the sensing film, thus increasing the signal-to-noise ratio. Moisture-proof overcoatings have been used to maintain a constant level of water inside the sensor films. The optical sensors are inexpensive to prepare and can be easily coupled to fiber optics for remote sensing capabilities. A fiber-optic bundle was used for the gas detection and shown to work as part of a multianalyte platform for simultaneous detection of multiple analytes. The studies reported here resulted in the development of sol-gel optical fluorescent sensors for CO(2) gas with sensitivity below that in the atmosphere (ca. 387 ppm). These sensors are a complementary approach to current FT-IR measurements for real-time carbon dioxide detection in environmental applications.

Bi2MoO6 microstructures: controllable synthesis, growth mechanism, and visible-light-driven photocatalytic activities

The hierarchical flower-like Bi2MoO6 microstructures have been prepared via a facile solvothermal approach, employing ethylene glycol as the reaction medium in the presence of ethylenediamine. The flake-like building units of the hierarchical, flower-like Bi2MoO6 were constructed by many smaller spherical particles. Reaction temperature, reaction time and the volume of ethylenediamine were studied and found to play crucial roles in the formation of the Bi2MoO6 architectures. A possible mechanism in the formation of the microstructures was proposed based on the results of the morphology evolution as a function of reaction time. The hierarchical flower-like Bi2MoO6 were found to exhibit highly efficient visible-light driven photocatalytic activities for the degradation of rhodamine B (RhB). Comparisons of three Bi2MoO6 microstructures with different morphologies suggest that the morphologies of the products have a great effect on the photocatalytic activities.