Xintai Su

Reduced graphene oxide anchored with zinc oxide nanoparticles with enhanced photocatalytic activity and gas sensing properties

Reduced graphene oxide (rGO)–zinc oxide (ZnO) composites were synthesized by a two-step hydrolysis–calcination method, using GO and Zn(Ac)2 as precursors. The structure and morphology of the as-prepared samples were characterized by thermogravimetric analysis, X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy and field emission scanning electron microscopy. It was shown that the well-dispersed ZnO nanoparticles (NPs) were deposited on rGO homogeneously. So far as ZnO NPs with different diameters were synthesized in the varied samples, the ZnO NPs with an average diameter of around 10 nm which were obtained at the heating temperature of 300 °C for 4 h exhibited higher photocatalytic activity than the others. A relatively low amount of rGO–ZnO composites (5 mg) demonstrated enhanced photocatalytic activity to decompose methyl orange (MO, 40 mg L−1) and methylene blue (MB, 10 mg L−1) under low-power ultraviolet light. Furthermore, rGO–ZnO composites exhibited high sensitivity, and a response can be achieved at 50.09 to 1000 ppm acetone. In addition, the ultraviolet light-induced photocatalytic mechanism as well as gas sensing mechanism was also discussed. Both rGO and crystallinity played important roles in improving photocatalytic activity and gas sensing properties.

Synthesis and microwave modification of CuO nanoparticles: Crystallinity and morphological variations, catalysis, and gas sensing

CuO nanoparticles with different morphologies were synthesized by chemical precipitation and subsequently modified by microwave hydrothermal processing. The nanoparticles were precipitated by the introduction of a strong base to an aqueous solution of copper cations in the presence/absence of the polyethylene glycol and urea additives. The modification of the nanoparticles was subsequently carried out by a microwave hydrothermal treatment of suspensions of the precipitates, precipitated with and without the additives. X-ray powder diffraction analysis indicated that the crystallinity and crystallite size of the CuO nanoparticles increased after the microwave hydrothermal modification. Microscopy observations revealed the morphology changes induced by microwave hydrothermal processing. The thermal decomposition of ammonium perchlorate and the detection of volatile gases were performed to evaluate the catalytic and gas sensing properties of the synthesized CuO nanoparticles.

Synthesis of nano-TiO2-decorated MoS2 nanosheets for lithium ion batteries

A facile process is developed to synthesize a TiO2–MoS2 nanohybrid via a one-pot hydrothermal route and post-annealing in an Ar atmosphere at 500 °C for 4 h. The precursor and target products were characterized by transmission electron microscopy (TEM) and field-emission scanning electron microscopy (FESEM). TEM and FESEM analysis showed that TiO2 nanoparticles with an average diameter of about 20 nm were uniformly distributed on MoS2 nanosheets. Electrochemical measurements demonstrated that the nano-TiO2-decorated MoS2 nanosheets exhibited excellent cycling stability and rate performance, which delivered a capacity of 604 mA h g−1 after 100 cycles at a current density of 100 mA g−1. The TiO2 is believed to act as a stabilizer to retain the MoS2 structure upon prolonged cycling. This material can be a promising candidate for the lithium ion batteries (LIBs).

Novel approach for synthesis of boehmite nanostructures and their conversion to aluminum oxide nanostructures for remove Congo red

A phase transfer method was developed to prepare boehmite (γ-AlOOH) nanostructures with various morphologies including nanofragments, nanorods, nanoflakes and multiply stacked nanostructures. The effect of the reaction temperature on the morphology of the as-prepared γ-AlOOH was investigated systematically. After calcination, the corresponding aluminum oxide (γ-Al2O3) nanostructures were obtained from the as-prepared γ-AlOOH products and preserving the same morphology. The obtained samples were characterized by several techniques, such as X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and N2 adsorption-desorption technique. The possible formation mechanism of the boehmites has also been proposed. Adsorption experiments indicated that γ-Al2O3 nanorods exhibited better adsorption capacity for Congo red (CR) in contrast to other as-prepared γ-Al2O3 nanostructures and commercial alumina (Al2O3), and the adsorption obeyed well to Langmuir isotherm model. Besides, the adsorption kinetics followed pseudo-second-order rate equation.

Controlled synthesis of CoO/C and Co/C nanocomposites via a molten salt method and their lithium-storage properties

We report a facile molten salt approach for the fabrication of CoO and Co nanoparticles, which homogeneously embedded in two-dimensional (2D) amorphous carbon nanosheets as an advanced anode materials for high-performance lithium-ion batteries (LIBs). With the aid of Na2SO4 particles, the ultra-small CoO/C or Co/C hybrid nanocomposites were synthesized simultaneously through a single heating procedure using the Co(OH)2@OA complex as the precursors for both CoO(Co) and thin carbon layers. The hybrid nanocomposites (C500, C600) exhibited an unexpected initial discharge capacity of 1618.2 and 873 mA h g−1 and high reversible specific capacity (642.1 and 500 mA h g−1 over 50 cycles at 70 mA g−1). The design of ultrafine CoO (Co) nanoparticles encapsulated with thin carbon layers can not only achieve long cycle life, but also effectively avoid the particle cracking, pulverization and aggregation upon cycling. Moreover, the findings open new paths for the exploiting of advanced active materials and electrolytes for Li ion batteries and other energy storage devices.

In2O3 nanocubes derived from monodisperse InOOH nanocubes: synthesis and applications in gas sensors

Monodisperse InOOH nanocubes have been synthesized by a facile two-phased solvothermal method via In(NO3)3·4H2O and sodium oleate as the starting materials. Subsequently, the InOOH nanocubes were coated on an alumina ceramic tube and aged at 300xa0°C for 3xa0days for the next gas sensing test. The XRD analysis illustrated that InOOH nanocubes had an orthorhombic phase structure consistent with the JCPDS cards number 73-1592. The XPS spectrum indicated that In and O exist on the surface of InOOH, and no impurity peaks were observed. The TEM results indicated that the InOOH are highly monodisperse nanocubes, with a mean size of 15xa0nm. After aging, cubic and hexagonal-coexisting In2O3 (JCPDS card number 88-2160 and card number 73-1809) were obtained, while the original cube shape was maintained. The gas response of the In2O3 was tested to several representative organic gases, and it displayed outstanding gas sensing performance toward ethanol, acetic acid, and ethyl acetate. Typically to 1000xa0ppm ethyl acetate vapor at 300xa0°C, the response is Ra/Rgxa0=xa0207.8. The results provide a facile route to prepare monodisperse nanoparticles for high-performance gas sensor.

Humate-assisted Synthesis of MoS2/C Nanocomposites via Co-Precipitation/Calcination Route for High Performance Lithium Ion Batteries

A facile, cost-effective, non-toxic, and surfactant-free route has been developed to synthesize MoS2/carbon (MoS2/C) nanocomposites. Potassium humate consists of a wide variety of oxygen-containing functional groups, which is considered as promising candidates for functionalization of graphene. Using potassium humate as carbon source, two-dimensional MoS2/C nanosheets with irregular shape were synthesized via a stabilized co-precipitation/calcination process. Electrochemical performance of the samples as an anode of lithium ion battery was measured, demonstrating that the MoS2/C nanocomposite calcinated at 700xa0°C (MoS2/C-700) electrode showed outstanding performance with a high discharge capacity of 554.9 mAh g−u20091 at a current density of 100xa0mAxa0g−u20091 and the Coulomb efficiency of the sample maintained a high level of approximately 100% after the first 3xa0cycles. Simultaneously, the MoS2/C-700 electrode exhibited good cycling stability and rate performance. The success in synthesizing MoS2/C nanocomposites via co-precipitation/calcination route may pave a new way to realize promising anode materials for high-performance lithium ion batteries.