Zhengguang Zou

A high performance wire-shaped flexible lithium-ion battery based on silicon nanoparticles within polypyrrole/twisted carbon fibers

Currently, mechanically flexible and strong batteries are desired for the development of bendable and portable devices. To meet this requirement, a simple and scalable synthesis of the anode for flexible wire-shaped lithium-ion batteries has been developed by a facile one-step in situ polymerization method. Polypyrrole was found to grow on the surface of Si nanoparticles and attach to twisted carbon fibers. The formed cross-linked structure of Si/PPy along with carbon fiber substrate offers a consecutive electron transport network and a porous structure to adjust large volumetric changes of Si particles during charging and discharging processes. On fabricating the wire-shaped Li-ion battery, the interconnected Si/PPy/CF hybrid electrode was found to offer an excellent performance of 3.9% capacity decrease after the flexibility test, a greatly improved cycling capacity of 2287 mA h g−1 and a capacity retention of about 75% after 100 cycles of the half-cell test. The all-wet methodology may provide a promising route for a new scalable way to produce applicable wire-shaped electrode in battery fabrication.

Solvent-free catalytic synthesis and optical properties of super-hard phase ultrafine carbon nitride nanowires with abundant surface active sites

High-quality ultrafine α/β-carbon nitride (α/β-C3N4) nanowires have been fabricated through a novel hot melt reduction synthetic method using polyvinylchloride ([–C2H3Cl–]n), ammonium chloride (NH4Cl) and ferric oxide (Fe2O3) as raw materials. The purity, structure, morphology, crystallinity and surface state of the as-prepared samples were investigated by FSEM, TEM, HRTEM, SAED, XRD, EDX, FTIR and XPS. The nanowires presented good crystallinity with a length range of 1–4 μm and an average diameter of about 10 nm. Every nanowire possessed a high specific surface area and rough surface with abundant exposed atoms/prominences, indicating that the surface structure will facilitate further surface modification, functionalization and related applications. In addition, UV-vis diffuse reflectance and the corresponding photoluminescence (PL) spectra indicated that the nanowires have a wide band gap (4.38 eV) and obvious ultraviolet luminescence properties at the maximum emission peak of about 340 nm. A catalytic reaction mechanism and the growth model were also proposed to explain the formation process of the C3N4 nanowires.

Synthesis of Flower-Like Cu2ZnSnS4 Nanoflakes via a Microwave-Assisted Solvothermal Route

Flower-like Cu2ZnSnS4 (CZTS) nanoflakes were synthesized by a facile and fast one-pot solution reaction using copper(II) acetate monohydrate, zinc acetate dihydrate, tin(IV) chloride pentahydrate, and thiourea as starting materials. The as-synthesized samples were characterized by X-ray diffraction (XRD), Raman scattering analysis, field emission scanning electron microscopy (FESEM) equipped with an energy dispersion X-ray spectrometer (EDS), transmission electron microscopy (TEM), and UV-Vis absorption spectra. The XRD patterns shown that the as-synthesized particles were kesterite CZTS and Raman scattering analysis and EDS confirmed that kesterite CZTS was the only phase of product. The results of FESEM and TEM show that the as-synthesized particles were flower-like morphology with the average size of 1~2 μm which are composed of 50 nm thick nanoflakes. UV-Vis absorption spectrum revealed CZTS nanoflakes with a direct band gap of 1.52 eV.

Morphology controlled synthesis and characterization of Bi2WO6 photocatalysts

Nest-like and multilayered-disk-like Bi2WO6 photocatalysts were synthesized through a hydrothermal strategy using thiourea and acetic acid as complexing agents. The nest-like Bi2WO6 showed excellent visible-light-driven photocatalytic performance, and it could decompose rhodamine B(RhB) within 100 minutes. This excellent performance resulted from its special microstructure and the relatively large surface area.

Hydrothermal synthesis and electrochemical performance of Mn-doped V6O13 as cathode material for lithium-ion battery

MnxV6−xO13 (x = 0.01, 0.02, 0.03, 0.04) were successfully synthesized via a simple hydrothermal method followed by heat-treatment. Both crystal domain size, electronic conductivity and the lithium diffusion coefficient of the MnxV6−xO13 samples were influenced by the doping amount of Mn2+. When x = 0.02, the product was nano-sized particles and exhibited the best electrochemical performance. The enhanced electrochemical performance originated from its higher total conductivity and higher lithium diffusion coefficient.

Mass Production of Bi 3 NbO 7 / Bi 2 Zn 2/3 Nb 4/3 O 7 composites and their visible-light photocatalytic activity

Series Bi3NbO7/Bi2Zn2/3Nb4/3O7 (BN/BZN) composites were synthesized through a facile solid state reaction method. The products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and UV-vis diffuse reflectance spectroscopy(DRS). When BN: BZN=0.1 mole ratio, the BN/BZN composite showed the best visible-light-driven photocatalytic performance, which decomposed nearly 100% of RhB (10 ppm, pH=3-4) within 40 min. The results demonstrated that in-situ solid state synthesis of BN/BZN composites could be an efficient strategy to develop new photocatalyst for environmental remediation.

Ribbon-like Cu doped V 6 O 13 as cathode material for high-performance lithium ion batteries

Ribbon-like Cu doped V6O13 was synthesized via a simple solvothermal approach followed by heat treatment in air. As an cathode material for lithium ion battery, the ribbon-like Cu doped V6O13 electrode exhibited good capacity retention with a reversible capacity of over 313 mAh·g−1 for up to 50 cycles at 0.1 C, as well as a high charge capacity of 306 mAh·g−1 at a high current rate of 1 C, in comparison to undoped V6O13 electrode (267 mAh·g−1 at 0.1C and 273 mAh·g−1 at 1 C). The high rate capability and better cycleability of the doped electrode can be attributed to the influence of the Cu ions on the mophology and the electronic conductivity of V6O13 during the lithiation and delithiation process.

In situ controlled rapid growth of novel high activity TiB2/(TiB2–TiN) hierarchical/heterostructured nanocomposites

In this work, a reaction coupling self-propagating high-temperature synthesis (RC-SHS) method was developed for the in situ controlled synthesis of novel, high activity TiB2/(TiB2–TiN) hierarchical/heterostructured nanocomposites using TiO2, Mg, B2O3, KBH4 and NH4NO3 as raw materials. The as-synthesized samples were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray energy dispersive spectroscopy (EDX), transition electron microscopy (TEM), high-resolution TEM (HRTEM) and selected-area electron diffraction (SAED). The obtained TiB2/TiN hierarchical/heterostructured nanocomposites demonstrated an average particle size of 100–500 nm, and every particle surface was covered by many multibranched, tapered nanorods with diameters in the range of 10–40 nm and lengths of 50–200 nm. In addition, the tapered nanorod presents a rough surface with abundant exposed atoms. The internal and external components of the nanorods were TiB2 and TiN, respectively. Additionally, a thermogravimetric and differential scanning calorimetry analyzer (TG-DSC) comparison analysis indicated that the as-synthesized samples presented better chemical activity than that of commercial TiB2 powders. Finally, the possible chemical reactions as well as the proposed growth mechanism of the TiB2/(TiB2–TiN) hierarchical/heterostructured nanocomposites were further discussed.

In situ synthesis of polycrystalline cubic boron nitride with high mechanical properties using rod-shaped TiB2 crystals as the binder

ABSTRACT Polycrystalline cubic boron nitride (PcBN) was sintered in the temperature range of 1050–1650°C under an ultra-high pressure of 5.0 GPa for 20 min using an in situ synthesis method. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and energy-dispersive spectrometry were used to study the compositional and morphological changes during the synthetic process. The results showed that rod-shaped TiB2 crystals could be detected at 1150°C, and their quantity increased with sintering temperatures. The TiB2 crystals distributed homogeneously and grew randomly among the cBN grain boundaries and interstitial spaces, ultimately forming an interlocking structure. The PcBN prepared at 1650°C exhibited optimal comprehensive mechanical properties, with a micro-hardness of 44.42 GPa and a flexural strength of 862.5 MPa. Moreover, based on the experimental results, the chemical reaction mechanism and the strengthening mechanisms occurred during the sintering process were also proposed to properly interpret the synthesis of PcBN.

Synthesis of In2Se3/CuSe Composite Powder by Solvothermal Method

The In2Se3/CuSe composite powders with the size in the range of 2-8µm for solar cell were successfully synthesized via using relatively simple solvothermal method at atmospheric pressure by the reaction between InCI3.4H2O, CuCI2.2H2O and Selenious acid and hydrazine hydrate in ethylene glycol.The influences of reaction temperature, reaction time, concentration of solution on the phase and morphology of In2Se3/CuSe composite powders were investigated. The phase and morphology of the products hSubscript textave been well studied by X-ray diffraction (XRD)and scanning electron microscope (SSubscript textEM) techniques.The study revealed that under the conditions of solvothermal method at atmospheric pressure, relative pure In2Se3 and CuSe powder were synthesized at temperatures of 160°C and 100°C respectively. The In2Se3/CuSe of irregular flake composite powders with the average size of 2-8µm had been obtained.The morphology of the products can be controlled by adding different kinds of surfactants such as PVP (Polyvinylpyrrolidone), CTAB (Hexadecyl trimethyl ammonium Bromide) and so on.