Guanghui Yue

Morphology-controlled synthesis, growth mechanism, optical and microwave absorption properties of ZnO nanocombs

ZnO nanocombs and nanorods with different morphologies have been successfully synthesized through a simple metal vapour deposition route at 600-750 degrees C using pure zinc powder or zinc and graphite powders as source materials. The structures and morphologies of the products were characterized in detail by using x-ray diffraction, scanning electron microscopy, transmission electron microscopy and laser Raman spectrometer. The morphologies of the products can be easily controlled by tuning the following four factors: reaction temperature, the distance between the source and the substrates, the kinds of substrates and the kinds of precursors. Possible growth mechanisms for the formation of ZnO nanostructures with different morphologies are discussed. Photoluminescence studies show that there are sharp UV and broad defect-related green emissions for all products. Relative intensity of the UV to defect-related green emissions decreases from ZnO nanorods to nanocombs. Microwave absorption properties of these nanocombs are also investigated. The value of the minimum reflection loss is -12 dB at 11 GHz for the ZnO nanocomb composite with a thickness of 2.5 mm.

High performance of Ge@C nanocables as the anode for lithium ion batteries

Germanium is a promising high-capacity anode material for lithium ion batteries. But as a huge volume variation always occurs during the charge/discharge process, it usually exhibits poor cycling stability. Herein, a low-cost Ge precursor was used for the preparation of Ge@C core–shell composited NWs by a facile and “green” synthetic route. The Ge@C nanocomposites, as anode materials for lithium-ion batteries, exhibited a high initial discharge capacity of 1648 mA h g−1 and superior rate capability. In particular, Ge@C nanocomposite electrodes maintained a reversible capacity of 1086 mA h g−1 after repeated cycling at a current density of 0.5 C (600 mA g−1) over 200 cycles.

Synthesis, Optical Properties and Photovoltaic Application of the SnS Quasi-one-dimensional Nanostructures

Low-toxicity single crystal SnS nanowires had been successfully synthesized by the catalyst-assistant chemical vapor deposition. Au nanoparticles were applied on the ITO surface as the catalysis, using SnS powder and S powder as forerunners. The structure, morphology and optical properties of the prepared SnS nanowires were characterized. The experimental results show the as-synthesized nanowires are single crystalline with a preferential orientation. The synthesized SnS nanowires show strong absorption in the visible and near-infrared spectral region, and the direct energy band gap of SnS nanowires is 1.46 eV.

Direct synthesis of hydrogen peroxide from plasma-water interactions

Hydrogen peroxide (H2O2) is usually considered to be an important reagent in green chemistry since water is the only by-product in H2O2 involved oxidation reactions. Early studies show that direct synthesis of H2O2 by plasma-water interactions is possible, while the factors affecting the H2O2 production in this method remain unclear. Herein, we present a study on the H2O2 synthesis by atmospheric pressure plasma-water interactions. The results indicate that the most important factors for the H2O2 production are the processes taking place at the plasma-water interface, including sputtering, electric field induced hydrated ion emission, and evaporation. The H2O2 production rate reaches ~1200u2009μmol/h when the liquid cathode is purified water or an aqueous solution of NaCl with an initial conductivity of 10500u2009μS cm−1.

CuCr2O4@rGO Nanocomposites as High-Performance Cathode Catalyst for Rechargeable Lithium–Oxygen Batteries

Rechargeable lithium–oxygen batteries have been considered as a promising energy storage technology because of their ultra-high theoretical energy densities which are comparable to gasoline. In order to improve the electrochemical properties of lithium–oxygen batteries (LOBs), especially the cycling performance, a high-efficiency cathode catalyst is the most important component. Hence, we aim to demonstrate that CuCr2O4@rGO (CCO@rGO) nanocomposites, which are synthesized using a facile hydrothermal method and followed by a series of calcination processes, are an effective cathode catalyst. The obtained CCO@rGO nanocomposites which served as the cathode catalyst of the LOBs exhibited an outstanding cycling performance for over 100 cycles with a fixed capacity of 1000xa0mAhxa0g−1 at a current density of 200xa0mAxa0g−1. The enhanced properties were attributed to the synergistic effect between the high catalytic efficiency of the spinel-structured CCO nanoparticles, the high specific surface area, and high conductivity of the rGO.

Facile synthesis of cuprous oxide nanoparticles by plasma electrochemistry

We report on a simple plasma electrochemistry method for synthesizing cuprous oxide (Cu2O) nanoparticles in the presence of glucose. In this system, Ar plasma in contact with a NaCl solution was used as one electrode, and a Cu plate was immersed in the solution as the counter electrode. The plasma-solution interaction produced many reducing and oxidizing species which can react with the Cu ions released from the Cu electrode. Cu2O nanoparticles, with an average diameter of 22 +/- 6 nm, were formed under the competition of reducing and oxidizing reactions in the solution. The results show that the glucose added in the electrolyte strongly influences the properties of the products. Corresponding to high, medium, and low concentrations of glucose, the products were nanoparticles from amorphous Cu2O, polycrystalline Cu2O, and a mixture of polycrystalline Cu2O and Cu2Cl(OH)(3), respectively.

Structure and Magnetic Properties of the Co-Ni Alloy Nanowires Prepared by AC Electrodeposition

Ordered Co-Ni nanowires have been fabricated by alternating current (AC) electrodeposition method using anodic porous alumina as a template. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) test results reveal that the samples are polycrystalline with uniform diameters around 50 nm and lengths up to several micrometers. X-ray diffraction (XRD) pattern indicate the crystalline structure change from fcc to hcp as the Co composition increasing. Magnetic measurements show that the nanowires have high magnetic anisotropy with their easy axis parallel to the nanowire arrays. The coercivity (Hc) and squareness (Mr/Ms) are found to increase with the increase of ferromagnetic Co component.