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A novel carbon--CoO--NiO--NiCo2O4 integrated electrode has been designed by reducing the hetero-structured NiCo2O4 nanosheet array with C2H2 on the nickel foam at a low temperature of 350 8C. The topotactical transformation from NiCo2O4 to the integrated electrode has been first conceived and investigated. Such unique nanoarchitectures exhibit excellent electrochemical performance with ultrahigh capacitance and desirable cycle life at high rates. [ABSTRACT FROM AUTHOR]

A novel two-step technique is introduced to synthesize BaSn(OH)6 nanorods. The method involves the preparation of precursor Na2Sn(OH)6 crystals in aqueous solution via hydrothermal method and the ion-exchange reaction between Na2Sn(OH)6 crystals and Ba2+ solution that followed, assisted by ultrasonic treatment. The BaSn(OH)6 nanorods array are formed due to the split of plate-formed Na2Sn(OH)6 during the ion-exchange treatment. The influence of the surfactant on the growth of the onedimensional (1D) BaSn(OH)6 nanostructures is investigated. In addition, the powder BaSnO3 has been obtained by thermal treatment at 450∘C for 5 h under inert gas protecting condition using BaSn(OH)6 nanorods as precursor. The 1D shape of BaSn(OH)6 was retained after thermal treatment. [ABSTRACT FROM AUTHOR]

Graphene and Au nanorods (AuNRs) coated with SiO2@TiO2 double shells (AuNR@SiO2@TiO2) were incorporated to form novel composite photoanodes in dye sensitized solar cells (DSSCs). The performances of the photoanodes and DSSCs are studied systematically. The short circuit current density (Jsc) and power conversion efficiency (PCE) of these composited DSSCs were greatly enhanced and the influences of the graphene, AuNRs and the SiO2@TiO2 double shells were revealed. The optimal properties with the maximal Jsc of 16.26 mA cm−2 and PCE of 8.08% are obtained in the DSSC co-doped with graphene and AuNR@SiO2@TiO2, significantly higher than those of the conventional DSSC with pure TiO2 photoanode by 37.7% and 32.9%, respectively. These significant enhancements in Jsc and PCE are attributed to the synergistic effect of graphene, the local surface plasma resonance of AuNRs, as well as the outer SiO2@TiO2 double shells, which result in the increased specific surface area and dye adsorption, the increased light absorption, the decreased charge transfer resistance R2 and electron recombination and thus the increased Jsc and PCE of the DSSCs. [ABSTRACT FROM AUTHOR]

Manipulating biomacromolecules and micro-devices with light is highly appealing. Opto driving torque can propel micro-rotors to translational motion in viscous liquid, and then separate microsystems according to their handedness. We study the torque of dielectric loss generated by circular polarized lasers. The unwanted axial force which causes the handedness independent translational motion is cancelled by the counter propagating reflection beams. The propelling efficiency and the friction torque of water are obtained by solving the Navier-Stokes equation. In the interesting range of parameters, the numerical friction torque is found to be linear to the angular velocity with a slope depending on the radius of rotor as r3. The time-dependent distribution of angular velocity is obtained as a solution of the Fokker–Planck equation, with which the thermal fluctuation is accounted. The results shed light on the micro-torque measurement and suggest a controllable micro-carrier. [ABSTRACT FROM AUTHOR]

Facile engineering ultrathin nano structural materials is still a huge challenge for material science. Thereinto, the strategy of exfoliating shows great advantages. In this work, we develop a convenient approach to exfoliate Co(OH)2 nanosheets into ultrathin Co(OH)2 nanoflakes through NaBH4-exfoliation method. Moreover, the microstructures of the Co(OH)2 nanosheets are conveniently controlled by varying the exfoliation time. As a result, the obtained ultrathin Co(OH)2-72 h nanosheets deliver the excellent electrochemical performance. In order to improve the energy storage properties, the obtained ultrathin Co(OH)2 nanosheets are further modified to enhance the conductivity via sulfidation. Consequently, the synthesized Co(OH)2-72 h/CoS2 composites exhibit a specific capacitance of 2536 F g−1 at 1 A g−1, which is more outstanding than that of Co(OH)2-72 h. What’s more, the Co(OH)2-72 h/CoS2 composites show a capacitance retention of 83.3% after 10 000 cycles. Besides, the assembled asymmetric supercapacitor displays a power density of 482 W kg−1 at an energy density of 36 Wh kg−1, demonstrating a large potential for application. [ABSTRACT FROM AUTHOR]

The Au nanoparticle sandwich double spheric-shells of SiO2@Au@TiO2 (SAT) microspheres are synthesized. The significant influence of the SAT microspheres on the properties of dye-sensitized solar cells (DSSCs) is investigated. Studies indicate that the introduction of SAT markedly enhanced the light scattering and capture ability of DSSCs and thus photogenerated electrons. DSSCs doped with 2.25 wt% SAT exhibit a maximum short circuit current density of 17.0 mA cm−2 and photoelectric conversion efficiency of 7.14%, which are remarkably higher than those of conventional DSSCs at 15.7% and 21.2%, respectively. The marked enhancement in the performance of the optimal DSSCs can be attributed to the synergetic complementary effect of the enhanced light scattering of the microspheres and to the localized surface plasmon resonance of the Au nanoparticles in the SAT, and is a novel promising way of enhancing the performance of DSSCs. [ABSTRACT FROM AUTHOR]

A high-performance supercapacitor electrode is designed and fabricated with the 3D interconnected continuous nanoporous Co/CoO core–shell hybrid nanostructure grown on nickel foam. The Co/CoO core–shell hybrid nanostructures are obtained via a hydrothermal method, followed by high-temperature annealing in hydrogen atmosphere, and finally placed in air at 50 °C for 1 h. The Co/CoO core–shell nanostructure assembled by a conductive metal–core and a CoO shell, brings low resistance, high specific capacitance of 5.632 F cm−2 and good capability stability (81.5% capacitance retention after 6000 cycles). An asymmetric supercapacitor device built by the Co/CoO (positive electrode) and activated carbon (negative electrode) can deliver a working voltage of 1.7 V and display a high energy density of 0.002 67 Wh cm−2 at a power density of 0.001 62 W cm−2, which is far superior to that of a supercapacitor at a similar power density. [ABSTRACT FROM AUTHOR]

This paper describes a facile solvothermal method to synthesize self-assembled three-dimensional (3D) Ni2+-Fe3+ layered double hydroxides (LDHs). Flower-like Ni2+-Fe3+ LDHs constructed of thin nanopetals were obtained using ethylene glycol (EG) as a chelating reagent and urea as a hydrolysis agent. The reaction mechanism and self-assembly process are discussed. After calcinating the as-prepared LDHs at 450 degC in nitrogen gas, porous NiO/NiFe2O4 nanosheets were obtained. This work resulted in the development of a simple, cheap, and effective route for the fabrication of large area Ni2+-Fe3+ LDHs as well as porous NiO/NiFe2O4 nanosheets. [ABSTRACT FROM AUTHOR]

Electrical field-induced strain response of electron-irradiated poly(vinylidene fluoride-trifluoroethylene) copolymer has been studied by a Mach-Zehnder type heterodyne interferometer in the frequency range of 3-9 kHz. The electrostrictive constant is calculated from the strain results, which is of the same order of magnitude as those obtained at 1 Hz by a bimorph-based strain sensor but at much lower electrical field. Changes in the dielectric property, phase transition behavior and crystal structure of the same copolymer have also been studied. The reversible solid-state transition between the polar and nonpolar phase in the crystalline regions of the copolymer driven by the external electric field is suggested to be responsible for the significant high electrostrictive strain of the electron-irradiated copolymer. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]