Jiming Song

Hierarchical structured bismuth oxychlorides: self-assembly from nanoplates to nanoflowers via a solvothermal route and their photocatalytic properties

A simple solvothermal route was explored to prepare hierarchical, nanostructured flower-like bismuth oxychlorides (BiOCl) by employing pyridine as the solvent. The volume ratios of distilled water to pyridine play an important role in the assembly of the BiOCl nanostructure from nanoplates to nanoflowers. The as-prepared BiOCl nanoflowers were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, and nitrogen sorption. The resulting BiOCl nanoflowers with high specific surface area were phase-pure and self-assembled from thin nanoplates during the reaction process. In addition, the photocatalytic properties of the as-prepared samples were further investigated by photocatalytic decomposition of methyl orange (MO) dye, and it was found that the BiOCl nanoflowers showed a higher photocatalytic activity than that of TiO2 (Degussa, P25) under modeling sunlight.

Enhanced electrochemiluminescence of CdSe quantum dots composited with graphene oxide and chitosan for sensitive sensor.

A novel strategy for the enhancement of electrochemiluminescence (ECL) was developed by combining CdSe quantum dots (QDs) with graphene oxide-chitosan (GO-CHIT). The ECL sensor fabricated with CdSe QDs/GO-CHIT composite exhibited high ECL intensity, good biocompatibility and long-term stability, and was used to detect of cytochrome C (Cyt C). The results show that the ECL sensor has high sensitivity for Cyt C with the linear range from 4.0 to 324 μM and the detection limit of 1.5 μM. Furthermore, the ECL sensor can selectively sense Cyt C from glucose and bovine serum albumin (BSA).

Fabrication of GO/PANi/CdSe nanocomposites for sensitive electrochemiluminescence biosensor.

A novel graphene oxide sheets/polyaniline/CdSe quantum dots (GO/PANi/CdSe) nanocomposites were successfully synthesized and used for the sensitive electrochemiluminescence (ECL) biosensing. The GO/PANi/CdSe nanocomposites were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), ultraviolet-visible (UV-vis) absorption spectroscopy, photoluminescence (PL) spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Finally, the nanocomposites were employed to construct the biosensor via layer-by-layer assembly for the ECL detection of Cytochrome C (Cyt C). The whole process was characterized by cyclic voltammogram (CV) and electrochemical impedance spectroscopy (EIS). Experimental parameters such as the ratio of GO/PANi, the K(2)S(4)O(8) concentration and the pH value of electrolyte solution were studied to investigate the effect on the ECL intensity. Under the optimized conditions, the ECL intensity decreased linearly with the Cyt C concentrations in the range from 5.0×10(-8) to 1.0×10(-4) M with detection limit of 2.0×10(-8) M. Besides, the as-proposed biosensor exhibits high specificity, good reproducibility, and stability, and may be applied in more bioanalytical systems.

Core–shell CeO2@C nanospheres as enhanced anode materials for lithium ion batteries

In this work, novel CeCO3OH@C nanocomposites were prepared via a one-pot approach by hydrothermal carbonization of a solution of glucose as a carbon precursor in the presence of Ce(NO3)3·6H2O and urea. It was found that glucose not only facilitates the formation of CeCO3OH nanoparticles, but also leads to a uniform, glucose-derived, carbon-rich polysaccharide (GCP) overlayer on the CeCO3OH nanocomposites. By adjusting the concentrations of glucose, the morphology of the samples was transformed from spindle nanoparticles to uniform spherical particles. CeO2@C with a core–shell structure was fabricated after calcining the CeCO3OH@C nanospheres under an N2 atmosphere. The obtained products were characterized by SEM, TEM, XRD, TG-DSC, FT-IR and charge–discharge test. The electrochemical performance test showed that these CeO2@C core–shell spheres as an anode material for lithium ion batteries exhibited an initial discharge specific capacity of 863.0 mA h g−1 in the potential range of 3.0–0.0 V. After 50 cycles, the capacity of the CeO2@C core–shell spheres was stabilized reversibly at about 355.0 mA h g−1. The improved cycling performance was attributed to the carbon shells, which can enhance the conductivity of the CeO2 core and suppress the aggregation of active particles during cycling. These CeO2@C core–shell spheres are promising anode materials for lithium ion batteries.

A novel enzymatic hydrogen peroxide biosensor based on Ag/C nanocables.

A novel enzymatic hydrogen peroxide sensor was successfully fabricated based on the nanocomposites containing of Ag/C nanocables and gold nanoparticles (AuNPs). Ag/C nanocables have been synthesized by a hydrothermal method and then AuNPs were assembled on the surface of Ag/C nanocables. The nanocomposites were confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDS). The above nanocomposites have satisfactory chemical stability and excellent biocompatibility. Cyclic voltammetry (CV) was used to evaluate the electrochemical performance of the Ag/C/Au nanocomposites at glassy carbon electrode (GCE). The results indicated that the Ag/C/Au nanocomposites exhibited excellent electrocatalytic activity to the reduction of H(2)O(2). It offered a linear range of 6.7×10(-9) to 8.0×10(-6) M, with a detection limit of 2.2×10(-9) M. The apparent Michaelis-Menten constant of the biosensor was 51.7×10(-6) M. These results indicated that Ag/C/Au nanocomposites have potential for constructing of a variety of electrochemical biosensors.

Graphene-like cobalt selenide nanostructures: template-free solvothermal synthesis, characterization and wastewater treatment

Hexagonal Co0.85Se with Ni0.85Se-type structure has been successfully synthesized without any surfactants by a solvothermal reduction route. SEM observation indicated that the obtained Co0.85Se nanostructures were of graphene-like morphology with a thickness less than 10 nm. The influence of the reaction temperature and the molar ratios of reactants has been studied in detail, and the results reveal the two reaction conditions play a crucial role in determining the final morphologies of the samples. The as-prepared product is determined to be ferromagnetic at room temperature from magnetic measurements. And the product with high specific surface area could be used as an adsorbent in wastewater treatment, which may be very useful for the environment.

Visible-Light Active and Magnetically Recyclable Nanocomposites for the Degradation of Organic Dye

Recyclable visible-light photocatalyst Fe3O4@TiO2 with core-shell structure was prepared by a simple synthetic strategy using solvothermal crystallization of titanium precursor on preformed Fe3O4 nanopartiles. The photo-degradation reaction of neutral red aqueous solution was tested to evaluate the visible-light photocatalytic activity of the as prepared Fe3O4@TiO2 nanoparticles, which show excellent photocatalytic activity compared with commercial P25 catalyst. Moreover, the Fe3O4@TiO2 nanocomposites can be easily separated from the reaction mixture, and maintain favorable photocatalytic activity after five cycles. The high visible light absorption of the Fe3O4@TiO2 nanocomposites may originate from the absence of electronic heterojunction, excellently dispersity and the high specific surface area of the as-synthesized Fe3O4@TiO2 samples.

Hierarchical flower-like Bi2WO6 hollow microspheres: facile synthesis and excellent catalytic performance

A one step method has been developed for the fabrication of hierarchical flower-like bismuth tungstate (Bi2WO6) hollow spheres via a solvothermal process. The size of these microspheres is about 1.5 μm, and the shells are composed of nanosheets with a thickness of about 15 nm. The product has a specific surface area of 95 m2 g−1. The formation mechanism of flower-like Bi2WO6 is proposed, which involves the nucleation and formation of nanoparticles followed by their self-assembly to microspheres, oriented growth, Ostwald ripening and transformation into flower-like hollow microspheres. The Bi2WO6 hollow spheres exhibit excellent visible light catalytic efficiency for the degradation of rhodamine B (RhB), up to 98% within 50 min. The efficiency remains at 92% after five photodegradation cycles due to the hierarchical hollow structure and large surface area.

One-pot synthesis of ZnO decorated with AgBr nanoparticles and its enhanced photocatalytic properties

Shuttle-like AgBr–ZnO nanocomposites were successfully synthesized via a facile chemical precipitation method using CTAB as both an cationic surfactant and Br− source. The structure, composition and morphology of the as-synthesized products were characterized by means of powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL) and the Brunauer–Emmett–Teller (BET) surface area measurements. The results revealed that the as-synthesized samples were single crystalline nanostructures with a shuttle-like morphology. The reaction temperature played an important role in the composition and morphology of the products. When the temperature was increased from 40 °C to 80 °C, the components of corresponding products changed from binary Ag–ZnO to ternary Ag–AgBr–ZnO, then to binary AgBr–ZnO, and the morphology underwent a change from aggregated nanoparticles to regular shuttle-like shaped crystals with diameters of ca. 200 nm and lengths of ca. 600 nm. Significantly, the as-prepared AgBr–ZnO nanocomposites showed enhanced photocatalytic properties for the degradation of Rhodamine B in aqueous solution under UV irradiation with a filter (λ = 365 nm) in comparison to the pure ZnO nanomaterials.

Solution-based synthesis and processing of Sn- and Bi-doped Cu3SbSe4 nanocrystals, nanomaterials and ring-shaped thermoelectric generators

Copper-based chalcogenides that comprise abundant, low-cost, and environmental friendly elements are excellent materials for a number of energy conversion applications, including photovoltaics, photocatalysis, and thermoelectrics (TE). In such applications, the use of solution-processed nanocrystals (NCs) to produce thin films or bulk nanomaterials has associated several potential advantages, such as high material yield and throughput, and composition control with unmatched spatial resolution and cost. Here we report on the production of Cu3SbSe4 (CASe) NCs with tuned amounts of Sn and Bi dopants. After proper ligand removal, as monitored by nuclear magnetic resonance and infrared spectroscopy, these NCs were used to produce dense CASe bulk nanomaterials for solid state TE energy conversion. By adjusting the amount of extrinsic dopants, dimensionless TE figures of merit (ZT) up to 1.26 at 673 K were reached. Such high ZT values are related to an optimized carrier concentration by Sn doping, a minimized lattice thermal conductivity due to efficient phonon scattering at point defects and grain boundaries, and to an increase of the Seebeck coefficient obtained by a modification of the electronic band structure with Bi doping. Nanomaterials were further employed to fabricate ring-shaped TE generators to be coupled to hot pipes, which provided 20 mV and 1 mW per TE element when exposed to a 160 °C temperature gradient. The simple design and good thermal contact associated with the ring geometry and the potential low cost of the material solution processing may allow the fabrication of TE generators with short payback times.