One-Step Synthesis of Graphene/Polyaniline Nanotube Composite for Supercapacitor Electrode

Graphene/polyaniline nanotube （GPNT） composite was synthesized using Vitamin C as both the template of polyaniline nanotube via in situ polymerization of aniline and the reducing agent of graphene oxide. The pure polyaniline （PANI）, graphene/PANI composite （GP） （using hydrazine monohydrate instead of VC） and GO/PANI composite were also prepared. IR spectroscopy and morphologies of the as-prepared samples were characterized. And the electrochemical performances were conducted on a three-electrode cell. IR spectroscopy demonstrated the in- teraction between graphene and PANI nanotube in GPNT, which is beneficial to enhance the electrochemical performance of the composite electrode. Surface morphology showed PANI nanotube with outer diameter of 140 nm in GPNT. GPNT composites exhibited better electrochemical performances than GP composite and pure PANI. The electrochemical performances showed that the specific capacitance of GPNT was 561 F/g which is more than that of either GP or PANI, it is not only due to the graphene which can provide good electrical conductivity and high specific surface area, but also associated with a good redox activity of ordered PANI nanotubes. The as-prepared GPNT composites with higher conductivity, lower resistance and better cycle life in our laboratory are promising electrode materials for high-performance electrical energy storage devices.

Lattice vibrational characteristics,crystal structures and dielectric properties of non-stoichiometric Nd_((1+x))(Mg_(1/2)Sn_(1/2))O_(3) ceramics

Non-stoichiometric Nd_((1+x))(Mg_(1/2)Sn_(1/2))O_(3)(-0.04=x≤0.04,NMS)ceramics were fabricated via a conventional solid-state reaction method.Crystal structures and morphologies were investigated by Xray diffraction(XRD)and scanning electron microscopy(SEM),respectively.The main crystalline phase is monoclinic Nd(Mg_(1/2)Sn_(1/2))O_(3) with a double perovskite structure(P21/n space group)for the NMS system proved by XRD.The sample at x=0.01 has the best crystallinity and evenly distributed crystal grains observed by SEM.The optimum performances(ε_(r)=19.87,Q×f=41840 GHz,f=12.05 GHz)are obtained at x=0.01.Lattice vibrational modes of the Raman spectra were assigned and illustrated,in detail.The dielectric properties obtained by fitting infrared reflectance spectra with the help of four-parameter semi-quantum model are consistent with the calculated values by microscopic polarization and damping coefficients.The reverse translational vibration of the NdeMgO_(6),the F_(5u)^((5)) mode,provides the greatest contribution to the dielectric response.The relationships between crystal structures and dielectric properties were mainly established using lattice vibrational modes as a media.