1,721,041 research outputs found
Graphene nanostructures for memristive devices
No full textMemristive nanoscale devices can generate intense fields by the application of relatively low voltages. This peculiar property allows fast, nonvolatile, and low-energy electrical switching as well as the possibility of retaining the internal resistance state according to the history of applied voltage and current. Memristors are predicted to revolutionize the current approaches in computer electronic architecture with their application, for instance, as resistive random access memory and for neuromorphic artificial intelligence. The use of graphene nanostructures for memristive switching systems offers an exciting alternative to other classes of materials, such as transition metal oxide and organic thin film
Method for the preparation of polyaniline/reduced graphene oxides composites
Full text linkThe present invention concerns a method for obtaining polyaniline/reduced graphene oxide composites comprising the steps of dispersing the graphene oxide in an acid aqueous solution containing an emulsifying agent to obtain a graphene oxide dispersion; dissolving one or more aniline oligomers in an organic solvent to obtain an oligomer solution; mixing the oligomer solution with the graphene oxide dispersion, said oligomer being added in a stoichiometric excess compared to the quantity required to complete the graphene oxide reduction; adding to the suspension of the polyaniline/reduced graphene oxide composite an oxidizing agent in a stoichiometric quantity compared to said excess of oligomer so as to oxidize the excess of said oligomer to obtain a suspension of the polyaniline/reduced graphene oxide composite
Metodo Per La Preparazione Di Compositi Di Polianilina E Ossido Di Grafene Ridotto
No full textThe present invention concerns a method for obtaining polyaniline/reduced graphene oxide composites comprising the steps of dispersing the graphene oxide in an acid aqueous solution containing an emulsifying agent to obtain a graphene oxide dispersion; dissolving one or more aniline oligomers in an organic solvent to obtain an oligomer solution; mixing the oligomer solution with the graphene oxide dispersion, said oligomer being added in a stoichiometric excess compared to the quantity required to complete the graphene oxide reduction; adding to the suspension of the polyaniline/reduced graphene oxide composite an oxidizing agent in a stoichiometric quantity compared to said excess of oligomer so as to oxidize the excess of said oligomer to obtain a suspension of the polyaniline/reduced graphene oxide composite
Inkjet Printed Negative Supercapacitors: Synthesis of Polyaniline-Based Inks, Doping Agent Effect, and Advanced Electronic Devices Applications
Full text linkLow frequency negative supercapacitors and high frequency negative capacitors are realized developing a polyaniline (PANI) based ink for piezoelectric inkjet printers, water based. PANI is synthesized by oxidation polymerization starting from the aniline dimer, thus avoiding the use of a toxic/mutagen substance such as aniline. In order to work in aqueous phase, the reverse addition of the dimer in the oxidative solution is made. The chlorinated emeraldine salt of PANI is produced and emeraldine base is prepared by dedoping. Two different doped PANI solutions are produced by solubilization of the emeraldine salt in dimethylsulphoxide and addition of respectively trifluorosulfonic acid and camporsulfonic acid, and then used as inks for the fabrication of inkjet-printed tracks of different geometries. The properties of inkjet-printed devices are characterized both in DC and AC regimes, showing very good performances under specific measurement conditions in terms of conductivity, as well as extremely interesting phenomena whose origin is still under debate, such as low frequency negative supercapacitance, high frequency negative capacitance and negative resistance. The realization of the highest negative supercapacitance realized so far, of -2.3 mF @ 30 Hz, corresponding to a specific mass capacity of -799 F g-1, is reporte
Zinc oxide nanostructures by chemical vapour deposition as anodes for Li-ion batteries
No full textZnO nanostructures are grown by a simple chemical vapour deposition method directly on a stainless steel disc current collector and successfully tested in lithium cells. The structural/morphological characterization points out the presence of well-defined polycrystalline nanostructures having different shapes and a preferential orientation along the c-axis direction. In addition, the high active surface of the ZnO nanostructures, which accounts for a large electrode/electrolyte contact area, and the complete wetting with the electrolyte solution are considered to be responsible for the good electrical transport properties and the adequate electrochemical behaviour, as confirmed by cyclic voltammetry and galvanostatic charge/discharge cycling. Indeed, despite no binder or conducting additives are used, when galvanostatically tested in lithium cells, after an initial decay, the ZnO nanostructures can provide a rather stable specific capacity approaching 70 µA h cm-2 (i.e., around 400 mA h g-1) after prolonged cycling at 1 C, with very high Coulombic efficiency and an overall capacity retention exceeding 62
Study of benzophenone grafting on reduced graphene oxide by unconventional techniques
No full textUnderstanding the mechanisms acting behind the functionalization of graphene is of paramount importance for the application of functionalized graphene in polymeric nano-composite materials. This work reports the study of the influence of benzophenone in a UV-mediated grafting process on graphene oxide, carried out by unconventional spectroscopic techniques, such as electron spin resonance and thermogravimetric analysis coupled with in situ infra-red spectroscopy. Using these techniques, a direct investigation of the grafting process was achieved for the first time, while up to now only indirect evidence was provided, opening new perspectives for the study of small molecule grafting on graphene sheets. The presence of benzophenone grafted onto the reduced graphene oxide surface was demonstrated, and in particular an unstable radical species attributable to the semipinacol radical of benzophenone was revealed, which is a key step of the functionalization process. Moreover, X-ray photoelectron spectroscopy demonstrated that the grafting process effectively reduced graphene oxide recovering the properties of graphene, contemporarily leaving active sites for further polymer functionalization
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