In this study, we developed a three-dimensional Co3O4 nanowire@NiO nanosheet core-shell construction array with an ultrathin porous shell as the electrode for a high performance capacitor. This electrode decreased the charge transfer resistance, exhibited an excellent electrochemical performance, and enhanced electron transfer capabilities. A specific capacity of 64 mAh g−1 at the current density of 0.5 A g−1 was obtained, which was greater than the 18 mAh g−1 of the Co3O4 nanowire array electrode. In addition, the Co3O4 nanowire@NiO nanosheet electrode exhibited a remarkable cycling stability, with 89% retention after 10000 cycles at 2 A g−1. The design of these core/shell composites provides a simple method to fabricate high performance electrodes for energy storage.

Hierarchical NiO nanospheres composed of porous nanosheets are prepared by a facile trisodium citrate assisted precipitation route followed by a calcination process. Effects of the trisodium citrate on the microstructure and electrochemical performances of NiO nanospheres are systematically investigated. The XRD, SEM, TEM, BET, and TG analyses show that the key point of the successful realization is that the citrate positioned in the precursor α-Ni(OH)2 layer, which can prevent the restacking of α-Ni(OH)2 sheets, yielding better crystallinity, high surface area (182 m2 g−1) as well as pore volume (0.15 cm3 g−1) and hierarchical porous ball-like morphology of NiO nanospheres by the calcination of the precursor. Electrochemical results show that the hierarchically porous NiO obtained with trisodium citrate assisted route exhibits high rate charge–discharge performance (463 F g−1 at 4.5 A g−1), longer cyclic stability (95% capacitance remained after 1000 charge–discharge cycles at 0.5 A g−1) as compared to the NiO prepared in the absence of sodium citrate (182 F g−1 at 4.5 A g−1; 70% capacitance retention after 1000 charge–discharge cycles at 0.5 A g−1). Further, due to facile mass transfer in the perfectly porous nanosheet, the citrate-assisted NiO show lower equivalent series resistance as revealed from the impedance studies.Graphical abstractHierarchical NiO microspheres composed of porous nanosheets were prepared by a facile trisodium citrate assisted precipitation route followed by a calcination process. The sodium citrate assisted obtained NiO has high specific surface area, large pore volume, and narrow pore size distribution. Significantly, compared with the ordinary NiO, the unique hierarchical NiO spheres showed a remarkable discharge capacity and electrochemical stability due to the unique morphology and pore size distribution. Highlights► NiO samples were synthesized using a facile trisodium citrate assisted route. ► Citrate positioned in the precursor interlayer to control the morphology and size. ► Citrate-assisted NiO showed higher specific capacitance and lower ESR. ► Citrate-assisted NiO exhibited good cycling stability and capacitance retention.

La3+ doped NiO microspheres with porous structure were fabricated using colloidal carbon spheres as hard template via a hydrothermal method followed by calcination process. The morphologies and microstructures of the samples were examined by scanning electron microscopy (SEM), transition electron microscopy (TEM) and X-ray diffraction (XPS). The key point of the successful realization was that the La3+-doped NiO microspheres exhibited smaller feature sizes, high specific surface area (277.5 m2 g−1)and large pore volume (0.79 cm3 g−1). Electrochemical properties were characterized by cyclic voltammetry and galvanostatic charge/discharge. The microstructure observations confirmed that La3+ ions were successfully doped into the NiO spheres after heat treatment, and the porous structure was achieved. As a result, 1.5 mol% La3+-doped NiO showed a remarkable specific capacitance of 253 F g−1 (2 times higher than that of the pure NiO) and good cycling stability (34% capacity increase after 500 cycles). These results demonstrate that La3+-doped NiO composites as electrode materials have potential application for high-performance supercapacitors.Graphical abstractLa3+-doped NiO spheres with porous structures were successfully fabricated via simple hydrothermal synthesis and calcination. The La3+-doped NiO microspheres exhibit smaller feature sizes, high specific surface area (277.5 m2 g−1) and large pore volume (0.79 cm3 g−1). Significantly, compared with the pure NiO, the La3+-doped NiO spheres showed a remarkable discharge capacity (253 F g−1) and electrochemical stability due to the unique morphology and pore size distribution.Highlights► Formation of porous structure of La3+-doped NiO via a hydrothermal method. ► Exhibited high specific surface area (277.5 m2 g−1) and large pore volume (0.79 cm3 g−1) of La3+-doped NiO spheres. ► Composite has high specific capacitance (253 F g−1), and good cycling stability over 500 cycles.

Diverse thiophene-containing blocks have been employed as the π-conjugated spacers of organic D-π-A dyes. In the case that multiple segments with distinguishable electronic features are applied, their conjugation sequence could potently affect optoelectric behaviors of photosensitizers in mesoscopic titania solar cells. In this work, we address this issue by designing three organic dyes (C225, C226, and C227), wherein the dihexyl-substituted cyclopentadithiophene moiety is stepwise shifted from the electron acceptor side to the donor one, along with the additional use of two 3-hexylthiophene rings as the conjugated spacing unit. With respect to C225 and C226, C227 presents a relatively inefficient photoinduced electron injection as indicated by photoluminescence measurements, which accounts for its lower efficiencies of converting incident monochromatic photons to collected electrons. Transient absorption measurements suggest that the charge recombination between oxidized dye molecules and titania electrons gradually decelerates from C225 to C227, while the interception of oxidized dye molecules by iodide ions exhibits an apparent driving force dependent, Marcus normal region behavior.

In order to enrich the variety of copper sulfide and enhance its currently existing applications, CuS nestlike hollow spheres assembled by microflakes were successfully synthesized through an oil−water interface route employing copper chloride, carbon disulfide, and sulfur as the starting materials in the presence of the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate. The composition, morphology, and structure of the product were characterized by X-ray powder diffraction, energy dispersive spectrometer, scanning electron microscopy, and transmission electron microscopy. The optical properties of the copper sulfide microstructures were investigated by UV−visible absorption spectra. Nestlike CuS microstructures were also explored as an additive to promote the thermal decomposition of ammonium perchlorate, and a thermogravimetric analysis technique was applied to investigate its catalytic performance. The results demonstrate that the product possesses good optical quality and catalytic performance, which indicate its broad potential applications. Because of its special hollow geometrical shapes and high surface areas, it can be used as catalysts, in sensors, as photonic crystals, and in light fillers. The current chemical strategy is expected to synthesize other metal sulfides or hollow structures.

C@LaCO3OH core-shell microspheres have been synthesized by a hydrothermal method using colloidal carbonaceous spheres (CCSs) as template and its by-products as reactant without any other precipitating agent added in the reaction system. The FT-IR and XRD results indicated the successful formation of the well-crystallized LaCO3OH shell with hexagonal crystal structure on the CCSs’ surface. The morphology and qualitative elemental chemical analysis were characterized by SEM, TEM, and EDS. The effects of co-solvent on the crystallinity of the LaCO3OH shell were also studied. In addition, PL result showed one emission band centered at 421 nm (λex = 365 nm) of the C@LaCO3OH microspheres. The UV–visible spectrum was also employed to investigate the optical property of the products. Further, a possible formation mechanism of the core-shell structure was proposed.