Benxian Li

Synthesis and characterization of multipod frameworks of Cu2O microcrystals and Cu7S4 hollow microcages

A variety of multipod frameworks of Cu2O microcrystals have been prepared through careful control of the ratios of n-butyl alcohol to water, and novel 14-pod Cu2O frameworks are first reported. Moreover, template-assisted synthesis of multipod frameworks of Cu7S4 microcages using the obtained Cu2O microcrystals as sacrificial templates is reported.

Microwave-assisted synthesis of Cu2O microcrystals with systematic shape evolution from octahedral to cubic and their comparative photocatalytic activities

Cuprous oxide (Cu2O) microcrystals with systematic shape evolution were successfully synthesized via a facile microwave-assisted heating technique. The monodispersed Cu2O was synthesized using copper acetate as a starting material, ethylene diamine tetraacetic acid (EDTA) as a reducing agent and surface-regulating agent and a mixture of water and n-butyl alcohol as reaction solvent. Various morphologies of Cu2O microcrystals, including octahedral, truncated octahedral, cuboctahedral, truncated cubic and cubic microcrystals, were obtained by altering the volume ratio of n-butyl alcohol to water. The morphologies and optical properties of the synthesized Cu2O microcrystals were characterized by XRD, SEM, TEM, HRTEM, SADE and UV-Vis/DRS. The growth mechanism of these crystals was thereby proposed. The volume ratio of n-butyl alcohol to water in the reaction medium was a critical factor in precisely controlling the morphologies of the microcrystals. Furthermore, their comparative photocatalytic activities for the degradation of methyl orange were tested.

Morphology-controlled synthesis and growth mechanisms of branched α-MnO2 nanorods via facile microwave-assisted hydrothermal method

Abstract Multiple branched manganese oxide nanorods were obtained through the rapid one-step microwave-assisted hydrothermal synthesis by the reduction of potassium permanganate in hydrochloric acid solution without using any catalysts or surfactants. The formation mechanism of the branched α-MnO2 was studied by systematically varying the reaction time, which were “oriented attachment” and rolling-cum-phase process. The electrochemical performance of the samples was examined by cyclic voltammetry. The specific surface area of the branched α-MnO2 and the electrolyte in the solution were found to remarkably affect the specific capacitance. This microwave-assisted technique enables the quick and simple preparation of branched MnO2 nanorods under mild conditions and maybe readily extended to the preparation of many other branched nanoparticles.

Single crystal of lanthanum hydroxide La(OH) 3 : Controlled synthesis by high pressure flux method and its growth mechanism

——————————— *Corresponding author. E-mail: wangxf103@jlu.edu.cn Received July 9, 2013; accepted September 3, 2013. Supported by the National Natural Science Foundation of China(No.21271082) and the Development of Science and Technology Plan of Jilin Province, China(No.20110341).

Synthesis of LiMn 2 O 4 Nano-wires via Flux Method and Their Usage as Cathode Material for Lithium Ion Batteries

LiMn2O4 nano-wires with ideal size distribution were readily synthesized by flux method. Samples prepared conventionally were used as the comparison references to investigate the effect of flux. The structural, morphological and electrochemical properties of nano-sized materials were examined by powder X-ray diffraction(XRD) analysis, scanning electron microscopy(SEM) and charge-discharge cycling analysis. Results from galvanostatic charge-discharge analysis show that the samples prepared at 700 °C via flux method(FM-700) afford the highest initial discharge capacity of 125.5 mA·h/g between 3.0 to 4.3 V at a rate of 0.2 C. After 50 cycles, a cycling retention of 89.6% is evident. Overall, the LiMn2O4 nano-wires developed in this work seem to be promising cathode materials for lithium ion batteries suitable to different energy-saving settings.

Special Tm3+ transition and white upconversion luminescence in the Yb3+/Tm3+ co-doped KMnF3

Special Tm3+ transition and a bright green light emission is first observed in the Yb3+/Tm3+ co-doped KMnF3, which are synthesized by the molten salt synthesis method. The RGB light emissions are simultaneously obtained with a single Tm3+ activator, and white upconversion luminescence is observed only by changing the reaction time.

Acetic Acid Assistant Hydrogenation of Graphene Sheets with Ferromagnetism

Ferromagnetism of pure carbon-based materials has been widely researched for several years. In therocially and experimentally, semi-hydrogenation graphene sheets exhibit ferromagnitism, which is related to the degree of hydrogenation. Here we reported the controllable hydrogenation of graphene using ball-milling method with acetic acid as hydrogenating agent. The hydrogenation graphene sheets were characterized by means of transmission electron microscopy(TEM), Raman spectroscopy and X-ray photoelectron spectroscopy, and magnetic measurement. The relusts of Raman spectroscopy demonstrate that the relative intensity of D band increases with the hydrogenation degree. The resluts of magnetic meansurement indicate the maximal magnetic moment of 0.274 A·m2/kg at 2 K for semi-hydrogenation graphene.

Temperature-dependent optical phonon behaviour of a spinel Zn2TiO4 single crystal grown by the optical floating zone method in argon atmosphere

The spinel Zn2TiO4 single crystals were grown via optical floating zone technology in an argon atmosphere for the first time, the as-grown crystals were dark blue and transparent. And the as-grown crystals, free of bubbles and with low angle grain boundary, grow along the a-axis direction. The annealed crystals were colorless and transparent, and the chemical valence of as-grown and annealed single crystals was characterized by X-ray photoelectron spectra. The room-temperature polarized Raman spectra of spinel Zn2TiO4 crystal were presented and the in situ temperature-dependent Raman spectra of the crystals were also described. DSC results of Zn2TiO4 were also discussed.

G0.5 PAMAM dendrimers improve the kinetic stabilization and nanoscale precipitation mechanism of amorphous calcium carbonate

A series of nanoscale amorphous calcium carbonate (nano-ACC) precipitates are prepared by alternating the concentration of carboxylic acid-terminated G0.5 poly(amidoamine) dendrimer with a CaCl2–Na2CO3 liquid–liquid phase which acts as a nucleation site at a fixed initial pH of 12 ± 0.2 at 15 °C. Analysis of the reaction time and particle size shows a four stage ACC precipitation mechanism including a combination of primary nucleation, secondary nucleation and diffusion controlled fast and slow growth, which is proved by electrical conductivity (EC) experiments. Moreover, the crystallization of calcite via vaterite is investigated. It is found that the stabilization of ACC and delay of the transformation from ACC to calcite via vaterite in aqueous systems is due to the surface activity and dendritic effect of G0.5, which have a significant effect on the kinetic process of the ACC nucleation stage.

Heterostructural MnO2@NiS2/Ni(OH)2 materials for high-performance pseudocapacitor electrodes

A new MnO2@NiS2/Ni(OH)2 heterostructure material was synthesized using a two-step hydrothermal process. The presence of 1D MnO2 nanosticks provided a substrate for the junction and facilitated the charge transmission. The grafting of NiS2/Ni(OH)2 sheets onto the surface of MnO2 enlarged the specific surface area (SSA) of the material. As a result, the SSA of the electrode material was improved and the capacitor performance was optimized. The material also showed a high rate capacity and long-term cycling capability.