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Transition metal oxides on reduced graphene oxide (TMO@rGO) nanocomposites were successfully prepared via a very simple one-step solvothermal process, involving the simultaneous (thermal) reduction of graphene oxide to graphene and the deposition of TMO nanoparticles over its surface. Texture and morphology, microstructure, and chemical and surface compositions of the nanocomposites were investigated via scanning electron microscopy, X-ray diffraction, micro-Raman spectroscopy, and X-ray photoelectron spectroscopy, respectively. The results prove that Fe2O3@rGO, CoFe2O4@rGO, and CoO@rGO are obtained by using Fe and/or Co acetates as oxide precursors, with the TMO nanoparticles uniformly anchored onto the surface of graphene sheets. The electrochemical performance of the most promising nanocomposite was evaluated as anode material for sodium ion batteries. The preliminary results of galvanostatic cycling prove that Fe2O3@rGO nanocomposite exhibits better rate capability and stability than both bare Fe2O3 and Fe2O3+rGO physical mixture.

The effect of the type of dopant (titanium and manganese) and of the reduced graphene oxide content (rGO, 30 or 50 wt %) of the &alpha, Fe2O3@rGO nanocomposites on their microstructural properties and electrochemical performance was investigated. Nanostructured composites were synthesized by a simple one-step solvothermal method and evaluated as anode materials for sodium ion batteries. The doping does not influence the crystalline phase and morphology of the iron oxide nanoparticles, but remarkably increases stability and Coulombic efficiency with respect to the anode based on the composite &alpha, Fe2O3@rGO. For fixed rGO content, Ti-doping improves the rate capability at lower rates, whereas Mn-doping enhances the electrode stability at higher rates, retaining a specific capacity of 56 mAhg&minus, 1 at a rate of 2C. Nanocomposites with higher rGO content exhibit better electrochemical performance.

The coupling of the electromagnetic field with an electronic transition gives rise, for strong enough light-matter interactions, to hybrid states called exciton-polaritons. When the energy exchanged between light and matter becomes a significant fraction of the material transition energy an extreme optical regime called ultrastrong coupling (USC) is achieved. We report a microcavity embedded p-i-n monolithic organic light emitting diode working in USC, employing a thin film of squaraine dye as active layer. A normalized coupling ratio of 30% has been achieved at room temperature. These USC devices exhibit a dispersion-less angle-resolved electroluminescence that can be exploited for the realization of innovative optoelectronic devices. Our results may open the way towards electrically pumped polariton lasers. (C) 2014 AIP Publishing LLC.

We report optical writing at the nanometer scale of spin coated PMMA-spiropyran films. By using a near-field optical microscope, pure optical nano-writing with a resolution of 160 nm and writing speed of 0.4 mu m/s was achieved. Simultaneous topographic and optical writing was also obtained by simply coupling to the near-field few more mW of laser power. Due to the fast optical response of the spiropyran molecule, nanolithography on PMMA-spyropyran thin films appears to be very attractive for future photonics applications. (C)2014 Optical Society of America