Flexible highly conductive films based on expanded graphite /polymer nanocomposites

Highly electrically and thermally conducting films of expanded graphite/polymer nanocomposites were fabricated using an approach based on solution mixing methods. The use of Hydroxyethylcellulose and benzylic alcohol based solutions provides efficient dispersion and better exfoliation of multilayer graphene (nanographite) flakes that are further aligned in extended 2D layers forming continuous conductive pathways during lamination (hot calendering) process. Very high electrical conductivity (190 S/cm) was obtained for fabricated layered films. In contrast, for films produced by a conventional mixing and deposition method with acrylic copolymer and the same nanographitic material, with flakes randomly distributed within the composite, much lower conductivities (2.4 S/cm) were obtained

Microwave-assisted synthesis and deposition of a thin ZNO layer on microwave-exfoliated graphene: optical and electrochemical evaluations

A rapid and facile microwave-assisted method has been developed for the deposition of a zinc oxide layer (ZnOL) in situ on partially microwave exfoliated graphene (MpEG). The formation of the ZnO layer on microwave partially exfoliated graphene (ZnOL@MpEG) hybrid only requires zinc nitrate and the MpEG sheets are reacted under a low level of microwave irradiation (700 W) for 5 min. The deposited thin ZnOL on the MpEG sheets is uniformly well-dispersed and covers the whole MpEG sheets. The as-prepared ZnOL@MpEG hybrids demonstrate enhanced electrochemical properties as supercapacitors and also show quenching phenomena for photoluminescence. The fluorescence quenching observed for the ZnOL@MpEG hybrids compared to ZnO, indicates photoinduced electron transfer from ZnO to the MpEG layers, which shows recombination of hole and electron charge carriers. The electrochemical measurements exhibit that the ZnOL@MpEG hybrids have a large integral area of the cyclic voltammetry loop, indicating that such hybrids are promising for application in supercapacitors. The material displayed a high specific capacitance of 347 F g(-1) at a current density of 5.0 A g(-1). A mechanism for the formation of the ZnOL@MpEG hybrids via the microwave method has also been proposed5836798867995CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPES

Microwave heating time dependent synthesis of various dimensional graphene oxide supported hierarchical ZNO nanostructures and its photoluminescence studies

Microwave heating reaction time dependent various graphene oxide based zinc oxide (G-ZnO) heterostructures such as graphene oxide-ZnO microcubes (GZMC), graphene oxide-ZnO nanoflakes (GZNF) and graphene oxide ZnO nanoneedles (GZNN) are synthesized by simple and cost effective microwave assisted exfoliation method. These heterostructures supported on graphene oxide nanosheets (GNSs) represent three dimensional (3D) ZnO microcubes and various confined two dimensional (2D) nanoflakes and one dimensional (1D) ZnO nanoneedles like structures. The recorded PL intensity variations show the strong evidence of the interfaces interaction between graphene oxide and ZnO heterostructures. However the differences in the PL intensities are also caused by the 3D and various confined G-ZnO heterostructures. The photoluminescence characterization of GZMC, GZNF and GZNN nanostructures exhibit a decrement in the PL intensity. The PL intensity of the GZNN is lowered by 67.50% and 39.7% to the GZMC and GZNF nanostructures respectively. The results show that ZnO heterostructures grown on GNSs with different morphologies and dimensionalities exhibit the variation in PL intensity due to preventing a direct recombination of the electrons and holes in ZnO. A tentative growth mechanism has been given for the growth of various graphene based zinc oxide heterostructures111291300CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPComision Nacional de Investigacion Cientifica y Tecnologica (CONICYT

A consistent multiphase SPH approximation for bubble rising with moderate Reynolds numbers

Phenomena involving bubble flow have an important role in numerous applications such as mixing, separation, filtration and cooling. When two different phases are treated as liquids gas, the surface tension and buoyancy must be taken into account. An alternative is proposed to simulate flow for two or more phases, using bubbles formation and the Navier Stokes equations in a Lagrangian formalism via smoothed particle hydrodynamics (SPH). It is a mesh-free method useful for applications with interface flow. Therefore, we have presented a set of numerical methodologies for SPH in multiphases. Surface tension interface is modeled using the continuum surface force (CSF) method. In order to avoid tension instability and interface penetrations, a background pressure based on the initial pressure between phases is included in the formulation. This model is implemented inside the prediction correction of time upgrade scheme. Examples of bubble rising around the fluid due to the gravitational force are rarely analyzed in the SPH literature, especially to parameterize density, viscosity, surface coefficient, particle size and boundary conditions. Thus, this work focus on the analysis of these parameters and their effects on the morphology, displacement and velocity of the bubble simulations. Finally, results demonstrate a good numerical stability and adequate multiphase description105119CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP54283/2014-22012/21090-

Electrochemical sensing of bisphenol using a multilayer graphene nanobelt modified photolithography patterned platinum electrode

An electrochemical sensor has been developed for the detection of Bisphenol-A (BPA) using photolithographically patterned platinum electrodes modified with multilayer graphene nanobelts (GNB). Compared to bare electrodes, the GNB modified electrode exhibited enhanced BPA oxidation current, due to the high effective surface area and high adsorption capacity of the GNB. The sensor showed a linear response over the concentration range from 0.5 μM–9 μM with a very low limit of detection = 37.33 nM. In addition, the sensor showed very good stability and reproducibility with good specificity, demonstrating that GNB is potentially a new material for the development of a practical BPA electrochemical sensor with application in both industrial and plastic industries