Search

Abstract: Co-precipitation method of SnCl2·2H2O and graphene oxide (GO) solution was performed to fleetly prepare graphene/SnO2 composite. The structure and composition of the nanocomposite were detected by means of XRD, SEM, TEM and FT-IR. The GO was reduced by bivalent tin ions to graphene nanosheet (GNS) via solution reaction and SnO2 nano-crystals with size of 4–6nm were homogeneously distributed on the matrix of GNS. It was found that the disorder degree of graphene in GNS/SnO2 composite prepared by the bivalent tin ion assisted reduction method was much lower than that of GNS obtained via pyrolysis reduction. The possible mechanism for this phenomenon was discussed in detail. The N2 adsorption tests showed an ink-bottle-like pore structure of GNS/SnO2 and the SnO2 nanoparticles were confined in the interlayer of GNS without agglomeration. These structural features were desirable and enabled GNS/SnO2 an excellent anode material in lithium ion battery. The electrochemical tests showed that the composite could deliver a reversible capacity of 775.3mAh/g and capacity retention of 98% after 50 cycles. [Copyright &y& Elsevier]

Abstract: A new porous graphene/NiO has been prepared successfully by hydrothermal method with graphene oxide solution, Ni(NO3)2·6H2O and urea as raw materials. The as-prepared composite is characterized by X-ray diffraction, Raman, FT-IR, SEM, TEM and nitrogen adsorption/desorption. It is shown that graphene sheets are well decorated by the NiO nanoparticles to form a hierarchical nanostructures with rich porosity (ca. 2–5nm) and large specific surface area (174.1m2 g−1). Electrochemical characterization demonstrates that the mesoporous graphene/NiO are capable of delivering a specific capacitance of 429.7Fg−1 at the current density of 200mAg−1 and offer good capacitance retention of 86.1% at 1Ag−1 after 2000 continuous charge–discharge cycles. These rich and evenly distributed porosity could reduce the transportation distance and offer a robust sustentation of OH− ions due to its “ion-buffering reservoirs”, ensuring that sufficient Faradaic reactions can take place at the surfaces of electroactive NiO nanoparticles. It suggests that the hierarchical nanostructure is helpful in improving the electrochemical performance of the oxide. [Copyright &y& Elsevier]