A novel method for preparing polyaniline/graphene (PANI/GN) nanocomposites was demonstrated by liquid-liquid interface polymerization method. Then the gold nanoparticles (Au NPs) were uniformly decorated on the PANI/GN surface to form gold/polyaniline/graphene (Au/PANI/GN) nanohybrids. The Au/PANI/GN nanohybrids film showed good electron transfer ability, which ensured high sensitivity to detect AFB1 in a range from 0.05 to 25 ng/mL with a detection limit of 0.034 ng/mL obtained at 3σ (n = 10). The proposed immunosensor provided a simple tool for AFB1 detection.
Two kinds of hard carbon (HC) were investigated as negative electrodes for sodium secondary batteries using Na[FSA]–[C3C1pyrr][FSA] as an ionic liquid electrolyte at 363 K. The structural properties of HCs were studied by X-ray diffraction (XRD), Raman spectroscopy, small-angle X-ray scattering (SAXS), and field-emission scanning electron microscopy (FE-SEM). The interlayer distance between graphene sheets and the pore size were different for these HCs. Potential slope and plateau regions were observed in charge–discharge curves, which is typical for HC negative electrodes. More detailed examinations revealed that the HC with a larger interlayer distance showed higher capacity in the slope region, while that with a larger pore size exhibited a higher capacity in the plateau region. Finally, the rate capabilities and cycling properties of HC negative electrodes were evaluated.
Fe3O4/graphene/carbon nanotubes composite was successfully synthesized through a facile solvothermal process. The Fe3O4 particles are dispersed in the three-dimensional (3D) conductive network forming by graphene nanosheets and cross-linked CNTs. As anode materials for lithium-ion batteries, the adding ratio of GO and CNTs in solvothermal process influences the electrochemical performance of the products. The obtained composite by the adding ratio of GO and CNTs 1:1 displays good electrochemical performance. The composite shows an initial charge capacity of 1244.9 and 1012.1 mA·h·g−1 after 200 cycles at a current density of 500 mA·g−1. At the current density of 1300 mA·g−1, it delivers 710.2 mA·h·g−1 after 200 cycles, remaining the initial charge capacity of 90.8%. In addition, the composite shows good coulomb efficiency and rate performance. The good performance of composite is described to the uniform distribution of Fe3O4 particles, graphene and CNTs in the 3D conductive network structure, which is beneficial for the electrolyte penetrating into the composite in all directions.
Charge and discharge properties of a graphite/SiOx composite electrode were studied over a wide range of charge/discharge rates (1/20 to 5 C) for use in automotive applications. The graphite/SiOx (90/10 by weight) composite electrode gave a high reversible capacity (453 mAh·g−1), and showed a good capacity retention at a low rate of 1/20 C. However, the capacity decreased significantly on cycling at a high rate of 2 C. From the analysis of the charging and discharging processes, it was found that the charging reaction occurs predominantly at SiOx particles initially at higher potentials and then proceeds at graphite particles at lower potentials to be fully charged. This tendency was also supported by a dependence of the activation energy of the charge transfer reaction on the state of charge (SOC) estimated by ac impedance analysis. Because the composite electrode contains only 10% SiOx, the current was excessively concentrated to the SiOx particles at the initial state when charged at high rates. This caused crack formation in SiOx particles, and the resulting contact loss between particles was considered as the reason for the observed poor cycleability at 2 C.