Xue-Tai Chen

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.

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.

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.

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.

Microwave-assisted hydrothermal synthesis of cube-like Ag-Ag 2 MoO 4 with visible-light photocatalytic activity

Cube-like Ag-Ag2MoO4 composite has been successfully prepared in the presence of PVP (polyvinylpyrrolidone) via a facile microwave-assisted hydrothermal process. Studies of its photocatalytic performance in the decomposition of RhB indicate that the cube-like Ag-Ag2MoO4 composite exhibits good catalytic activities under visible-light irradiation. The face that Ag promotes the absorption of visible light may be attributed to the surface plasmon resonance. Further XRD characterization after recycle photocatalytic tests confirms that partial Ag+ ions in Ag2MoO4 have been reduced to metallic Ag. Reaction temperature, reaction time and the amount of PVP have also been studied and found to play crucial roles in the formation of the cube-like microstructures.

Pb(dca)2(dca = dicyanamide): a novel 3D compound with unusual coordination modes of dicyanamide

The crystal structure determination of Pb(dca)2 reveals a new M(dca)2 structural type with two unusual coordination modes of dicyanamide existing in a novel (4,5,9)-connected 3D-polymeric structure, indicating the versatile coordination behaviour of both dicyanamide and lead atom.

Pancake-like Fe2(MoO4)3 microstructures: microwave-assisted hydrothermal synthesis, magnetic and photocatalytic properties

A fast and economical route based on microwave-assisted hydrothermal reaction has been developed to synthesize pancake-like Fe2(MoO4)3 microstructures. The phase and morphology of the products have been 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). Several factors, including the amount of nitric acid, reaction time, temperature and iron source, play crucial roles in the formation of the Fe2(MoO4)3 multilayer stacked structures. Detailed studies indicate that the oriented attachment and layer-by-layer self-assembly of nanosheets is responsible for the formation of these structures. The magnetic and photocatalytic properties of the product have also been investigated.

Solvothermal preparation of Cu2O crystalline particles

Abstract A solvothermal process has been developed to prepare both the cubic single crystals and the spherical polycrystals of Cu 2 O by the reduction of CuSO 4 ·5H 2 O with d -glucose as a reductant in the presence of the different organic additives such as ethylene glycol, polyethylene glycol 200 (PEG-200), polyethylene glycol 400 (PEG-400), polyethylene glycol 10000 (PEG-10000), polyethylene glycol 20000 (PEG-20000) or polyvinyl pyrrolidone (PVP K-30). All the products were characterized using X-ray diffraction and transmission election microscopy. The organic additives were found to play a key role in the formation of the Cu 2 O crystals and lead to the different microstructures of the resultant Cu 2 O. Two different mechanisms, diffusion mechanism and aggregation mechanism, were used to explain the formation of single crystals and polycrystals of Cu 2 O, respectively. When PEG-10000, PEG-20000 or PVP K-30 was added into the reaction system, a diffusion mechanism contributes to the formation of the single crystals of Cu 2 O, while aggregation mechanism prevails in the polycrystals of Cu 2 O with EG, PEG-200 or PEG-400. The pH of the mixture was also found to be a key factor in deciding the final products.