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Abstract: CoFe2O4 flower-like microspheres are prepared via a surfactant- and template-free method, involving the controlled hytrothermal synthesis firstly and a subsequent thermal decomposition treatment. The microspheres with diameters of 3–4 μm are characterized by the assembly of numerous porous and inter-connected lamella structures. Lithium-ion batteries electrodes based on the as-prepared CoFe2O4 microspheres show a high specific capacity of 733.5 mAh g−1 after 50 cycles at a current density of 200 mA g−1 and a good cyclic stability, as well as excellent rate capability. The enhanced electrochemical performance can be attributed to the hierarchical microsphere structure with high sufficient interfacial contact area between the microspheres and electrolyte, the short diffusion distance of Li+, better accommodation of structural stress and volume change with the lithiation/delithiation process. It is suggested that the CoFe2O4 microsphere is one of the most promising candidates for high-performance lithium-ion batteries. [Copyright &y& Elsevier]

Abstract: A hierarchically Fe2O3@Co3O4 nanowire array is prepared by the aid of hydrothermal synthesis and sacrificial hydrolysis method. The obtained nanowire array shows hierarchical porosity and large surface area. The resulted Fe2O3@Co3O4 nanowire array is evaluated as an anode material for Li ion batteries, which exhibits high capacity and good cycle stability (1005.1 mAh g−1 after 50 cycles at a current density of 200 mA g−1) and an excellent rate performance, mainly owing to the unique hierarchical nanowire architecture and an elegant synergistic effect of two electrochemically active materials. The developed strategy can be readily generalized to construct other multifunctional hybrid nanostructures, which will be promising materials for high-performance electrochemical devices. [Copyright &y& Elsevier]

Abstract: Porous Fe3O4/C core/shell nanorods have been prepared by a facile hydrothermal method using porous Fe2O3 nanorods as the precursor and glucose as the carbon source. The Fe3O4/C nanorods possess a uniform size with 50–80nm in diameter and 300–500nm in length, and are homogenously coated by amorphous carbon layer. The porous nanorods greatly increase the electrical contact, thus facilitating the Li-ion and electron transportation, and enhancing the reactivity of the electrode. Also, the carbon layer can effectively limit the volume expansion and detachment of Fe3O4, and thus increase its structure stability during cycling. In the context of lithium storage behavior, the Fe3O4/C nanorod electrode shows high capacity and good cycle stability, as well as enhanced rate performance. After 50 cycles, the reversible capacity of the porous Fe3O4/C nanorods is 762.1mAhg−1 at 0.1C and 597.2mAhg−1 at 0.5C, much higher than that of α-Fe2O3 nanorods (276.4mAhg−1) and Fe3O4 nanoparticles (307.9mAhg−1). At a high rate of 1C, the specific capacity of Fe3O4/C nanorods is still as high as 630.1mAhg−1. [Copyright &y& Elsevier]

Abstract: TiO2@WO3 core/shell nanorod arrays are prepared by the combination of hydrothermal and electrodeposition method. The array films show remarkable enhancement of the electrochromic properties. In particular, a significant optical modulation (57.2% at 750nm, 70.3% at 1800nm and 38.4% at 10μm), fast switching speed (2.4s and 1.6s), high coloration efficiency (67.5cm2 C−1 at 750nm) and excellent cycling performance (65.1% after 10,000 cycles) are achieved for the core/shell nanorod arrays. The improved electrochromic properties are mainly attributed to the core/shell structure and the porous space among the nanorod array, which makes the ion diffusion become easier and it also gives larger surface area for charge-transfer reactions. The data present great promise for the TiO2@WO3 core/shell nanorod arrays as practical electrochromic materials. [Copyright &y& Elsevier]

A porous Co3O4 nanoflake array film grown on nickel foam is prepared by a hydrothermal synthesis for pseudo-capacitor application. The pseudocapacitive behavior of the Co3O4 nanoflake array is investigated by cyclic voltammograms (CV), galvanostatic charge–discharge tests and electrochemical impedance spectroscopy (EIS) in 2 M KOH at different temperatures. The specific capacity is 210, 289 and 351 F g−1 at 2 A g−1 tested at −5 °C, 25 °C and 60 °C, respectively, corresponding to that of 184, 243 and 242 F g−1 at 20 A g−1. After 4000 cycles at 2 A g−1, the remaining specific capacity is 187, 342 and 124 F g−1 tested at −5 °C, 25 °C and 60 °C. It shows that with increasing the temperature from −5 °C to 60 °C, the specific capacity increases, while the cycling stability becomes worse. The operation temperature has a pronounced influence on the pseudocapacitive performance of Co3O4 nanoflake array. [ABSTRACT FROM AUTHOR]

Highlights: [•] Co3O4/C nanosheet array on nickel foam was synthesized by hydrothermal method, followed by magnetron sputtering of a carbon layer. [•] The Co3O4/C nanosheet array electrode delivers an initial discharge capacity of 1340.4mAhg−1 at 0.1C. [•] After 100 cycles, the capacity retention of the Co3O4/C is 88.8% of its initial discharge capacity. [•] The enhanced electrochemical performances are attributed to the porous nanosheet array and the thin carbon layer coated on Co3O4 nanosheets. [ABSTRACT FROM AUTHOR]