ating Hu

Microwave-Assisted Synthesis of Graphene Nanosheets–Gold Nanocomposites with Enhancing Electrochemical Response

Graphene nanosheets–gold (GNS-Au) nanocomposites have been successfully prepared by microwave radiation in aqueous media via a rapid one-step method. The as-obtained nanocomposites were characterized by Fourier transform infrared spectra, X-ray power diffraction, transmission electron microscopy, energy-dispersive X-ray spectrometry, Raman spectrum and UV-visible absorption spectra. The results show that Au nanoparticles with a mean diameter of 9.3 nm are densely coated on the surface of graphene nanosheets, which disturbs the van der Waals interactions and prevents graphene nanosheets from approaching each other. Cyclic voltammetry measurements reveal that GNS–Au modified glassy carbon electrode (GNS–Au/GCE) has a greatly enhanced electrochemical response compared with bare GCE and the GNS modified glassy carbon electrode (GNS/GCE), suggesting that the GNS–Au nanocomposites may be a promising nanomaterial for highly sensitive electrochemical sensors.

Large-scale Synthesis of Carbon Nanospheres by Catalyzed Pyrolysis of Tree Leaves

The zeta potential measurement with a rotating disk (RDZP) is a technique originally developed for disk-shaped planar solid samples. In this work, the feasibility of using this technique for pigments powder was studied. The raw material of these pigments came from the desliming step of banded iron formation ore processing. This tailing contains mainly iron oxides ( 76 wt%) and particles with average size around 4 μm, which make it a potential pigment. Two different pigments were investigated. The “as produced” mud (brown hue) and that obtained after thermal treatment at 1,000 °C (red hue). Characterization tests were carried out by X-ray fluorescence (XRF), X-ray diffraction (XRD), thermogravimetric analysis (TG), differential thermal analysis (DTA), and laser granulometry. Color measurements of the pigments were performed using the CIELab system. The RDZP analyses of the pigments agree well with those reported in the literature using the traditional technique of mass transport by electrophoretic motility. The zeta potential measurements showed that the dispersion of the pigments in ammonium hydroxide solution with Ph = 14, ensuring absolute zeta potential values above 500 mV, is necessary to avoid pigment agglomeration when preparing styrene-acrylic paints.