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Using ultrasonication we succeed in a controlled incorporation of TiO(2) nanoparticles on the graphene layers homogeneously in a few hours. The average size of the TiO(2) nanoparticles was controlled at around 4-5 nm on the sheets without using any surfactant, which is attributed to the pyrolysis and condensation of the dissolved TiCl(4) into TiO(2) by ultrasonic waves. The photocatalytic activity of the resultant graphene-TiO(2) composites containing 25 wt.% TiO(2) is better than that of commercial pure TiO(2). This is partly due to the extremely small size of the TiO(2) nanoparticles and partly due to the graphene-TiO(2) composite structure consisting of homogeneous dispersion of crystalline TiO(2) nanoparticles on the graphene sheets. As the graphene in the composites has a very good contact with the TiO(2) nanoparticles it enhances the photo-electron conversion of TiO(2) by reducing the recombination of photo-generated electron-hole pairs.

Large-scale, substrate-free graphene, with few-layered sheets, is synthesized by the CVD of methane over cobalt supported on magnesium oxides at 1000 -C in a gas flow of argon. Typically, 50 mg of the few-layered graphene materials over 500 mg of the Co/MgO catalysts are synthesized under our experimental conditions. Randomly aggregated, thin, crumpled graphene sheets stacked closely together are produced. Both carbon (94.6 at.-%) and oxygen (5.4 at.-%) are present in the graphene sheets. The oxygen may originate from air adsorbed on the graphene sheets. Our results indicate the presence of localized sp 3 defects within the sp 2 carbon network and small sp 2 domains in the few-layered graphene particles.

Covalent adaptable networks (CANs) represent a transition material combining favorable features of thermosets and thermoplastics. However, it is still a huge challenge to simultaneously achieve fast reprocessability and high performance for CANs. Here, we designed catechol-based acetal CANs to achieve continuous reprocessing without sacrificing thermal and mechanical properties. A small-molecule model study demonstrated the significantly accelerated acetal exchange by neighboring group participation (NGP) of phenolic hydroxyl. Using this internally catalyzed acetal chemistry, a series of CANs with a broad range of properties were simply prepared from bio-based epigallocatechin gallate (EGCG) and tri­(ethylene glycol) divinyl ether (TEGVE) via one-step “click” cross-linking without using catalysts or releasing small-molecule byproducts. The dynamic nature of the CANs was confirmed via stress relaxation and multiple recycling methods including extrusion. While the dense cross-link density and high rigidity of the network provided high solvent resistance and mechanical properties. This work provides a promising and practical method to produce fast-reprocessing dynamic covalent polymer networks with dense cross-link density and superior performance.

Conventional thermosets are infusible and insoluble covalently cross-linked polymers which are difficult to be recycled and reused when discarded. Recent years witnessed development of closed-loop recycling of novel thermosets as...

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A new route is presented for the synthesis of Si nanoparticle/Graphene (Si-Gr) composite by a sonochemical method and then magnesiothermic reduction process. During the process, silica particles were firstly synthesized and deposited on the surface of graphene oxide (SiO2-GO) by ultrasonic waves, subsequent lowtemperature magnesiothermic reduction transformed SiO 2 to Si nanoparticles in situ on graphene sheets. The phase of the obtained materials was influenced by the weight ratio of Mg to SiO 2-GO. With the optimized ratio of 1 : 1, we can get Si nanoparticles on Gr sheets, with the average particle size of Si around 30 nm. Accordingly, the resultant Si-Gr with 78 wt% Si inside delivered a reversible capacity of 1100 mA h g-1, with very little fading when the charge rates change from 100 mA g-1 to 2000 mA g-1 and then back to 100 mA g-1. Thus, this strategy offers an efficient method for the controlled synthesis of Si nanoparticles on Gr sheets with a high rate performance, attributing to combination of the nanosized Si particles and the graphene. 2013 The Royal Society of Chemistry. . Thus, this strategy offers an efficient method for the controlled synthesis of Si nanoparticles on Gr sheets with a high rate performance, attributing to combination of the nanosized Si particles and the graphene.

Nanometer-sized fluorescent particles were successfully synthesized. The nanoparticles have a narrow, tunable, symmetric emission spectrum and a broad, continuous excitation spectrum. They are also photochemically stable. A synchronous fluorescence method was developed for the rapid determination of DNA with functionalized CdS as a fluorescence probe, based on the synchronous fluorescence quenching of functionalized CdS in the presence of DNA. Maximum fluorescence is produced at pH 7.0, with maximum excitation and emission wavelengths of 360 and 620 nm, respectively. The maximum emission wavelength of synchronous fluorescence is 354 nm when delta lambda = 260 nm. Under optimum conditions, the calibration graphs are linear over the range 0-3.5 microg mL(-1) for calf thymus DNA (CT-DNA) and 0.2-3.0 microg mL(-1) for fish sperm DNA. The corresponding detection limit is 0.01 microg mL(-1) for CT-DNA and 0.02 microg mL(-1) for fish sperm DNA. The relative standard deviation of seven replicate measurements is 2.2% for 1 microg mL(-1) calf thymus DNA and 2.4% for 1 microg mL(-1) fish sperm DNA. The method is simple, rapid and sensitive. The recovery and relative standard deviation are very satisfactory.