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Abstract: Graphene encapsulated nanosheet‐assembled ZnO‐Mn‐C hierarchical hollow microspheres are produced through a simple yet effective dual electrostatic assembly strategy, followed by a heating treatment in inert atmosphere. The modification of graphene sheets, metal Mn, and in situ carbon leads to form 3D interconnected conductive framework as electron highways. The hollow structure and the open configuration of hierarchical microspheres guarantee good structural stability and rapid ionic transport. More importantly, according to the density functional theory calculations, the oxygen vacancies in the hierarchical microspheres would cause an imbalanced charge distribution and thus the formation of local in‐plane electric fields around oxygen vacancy sites, which is beneficial for the ionic/electronic transport during cycling. Due to this multiscale coordinated design, the as‐fabricated graphene encapsulated nanosheet‐assembled ZnO‐Mn‐C hierarchical hollow microspheres demonstrate good lithium storage properties in terms of high reversible capacity (1094 mA h g−1 at 100 mA g−1), outstanding high‐rate long‐term cycling stability (843 mA h g−1 after 1000 cycles at 2000 mA g−1), and remarkable rate capability (422 mA h g−1 after total 1600 cycles at 5000 mA g−1). [ABSTRACT FROM AUTHOR]

Zinc-nickel citrate microspheres are prepared by a simple aging process of zinc citrate solid microspheres in nickel nitrate solution. As the concentration of nickel nitrate solution increases, the morphology of the produced zinc-nickel citrate evolves from solid, yolk-shell to hollow microspheres. The formation mechanism of different zinc-nickel citrate microspheres is discussed. After annealing treatment of the corresponding zinc-nickel citrate microspheres in air, three different ZnO-NiO hybrid architectures including solid, yolk-shell and hollow microspheres can be successfully fabricated. When applied as the anode materials for lithium ion batteries, ZnO-NiO hybrid yolk-shell microspheres demonstrate the best electrochemical properties than solid and hollow counterparts. After 200th cycles, ZnO-NiO hybrid yolk-shell microspheres deliver a high reversible capacity of 1176 mA h g−1. The unique yolk-shell configuration, the synergetic effect between ZnO and NiO and the catalytic effect of metal Ni generated by the reduction of NiO during discharging process are responsible for the excellent lithium storage properties of ZnO-NiO hybrid yolk-shell microspheres. [ABSTRACT FROM AUTHOR]

Abstract ZnO has attracted enormous research interest as anode material in lithium ion batteries due to its large theoretical capacity. Unfortunately, the development of ZnO-based anode materials is greatly bottlenecked by their poor capacity retention and limited cyclic life. Herein, ingeniously designed 3D graphene encapsulated ZnO-NiO-CuO double-shelled hollow microspheres (DSHM@RGO) have been prepared by a facile surfactant-assisted assembly method. Benefiting from their unique features including the large specific surface area, the double-shelled hollow architecture, the modification of graphene and the nanoscale building blocks, the DSHM@RGO anode exhibits enhanced electrochemical performances. A high reversible capacity of 559 mA h g−1 is delivered after 100 cycles at a current density of 1.0 A g−1. When cycled at a large current density of 3.0 A g−1, the as-obtained DHSM@RGO still delivers a relative high specific capacity of 366 mA h g−1. Highlights • 3D graphene encapsulated ZnO-NiO-CuO hollow microspheres are fabricated. • The modification of graphene benefits the transportation of electrons. • The hollow structure can enhance structural stability of active materials. [ABSTRACT FROM AUTHOR]

Yolk-shell ZnO-Ni-C wrapped with reduced graphene oxide (RGO) hybrid structures were successfully fabricated by annealing treatment of amorphous yolk-shell zinc-nickel microspheres precursor. The special structures possessing core@void@shell configuration have excellent electromagnetic (EM) wave absorption properties, owing to void space could adjust impedance mismatching. Meantime, the RGO-wrapped yolk-shell ZnO-Ni-C microspheres increased the content of defects and generated more effective interfacial polarization response to EM wave radiation. As a result, the minimum value of reflection loss (RL) of ZnO-Ni-C/RGO is −59.3 dB at 15.2 GHz with a thickness of 2.05 mm and the effective attenuation bandwidth is in a broad range from 12.4 to 18 GHz. [ABSTRACT FROM AUTHOR]

Zinc-copper citrate porous, yolk-shell and hollow microspheres are controllably produced via a facile electrostatic interplay between zinc citrate solid microspheres and copper sulphate solution with controllable concentration. By calcination of the firstly acquired zinc-copper citrate precursors in inert atmosphere, the corresponding ZnO-Cu-C porous, yolk-shell and hollow hybrid microspheres are synthesized. When adopted as the electrode materials for lithium ion batteries, the produced ZnO-Cu-C yolk-shell hybrid microspheres depict higher reversible capacity and better cycling stability than ZnO-Cu-C porous hybrid microspheres. After 500 cycles at 200 mA g −1 , yolk-shell hybrids deliver a reversible capacity of 769 mA h g −1 . Additionally, ZnO-Cu-C hollow hybrid microspheres exhibit best rate capability, which is due to their special three dimensional Cu conductive network. [ABSTRACT FROM AUTHOR]

Hybrid nanostructures containing multiple components have received intensive interests. Herein, we report a solution method for the preparation of Au–ZnO/graphene nanocomposites in which multi-branched Au–ZnO hybrid nanocrystals with ZnO nanorods growing on octahedral Au cores are anchored on graphene. The as-prepared hybrid nanocrystal and nanocomposite samples are characterized by transmission electron microscopy, X-ray diffraction and ultraviolet visible spectroscopy. The photocatalytic activity is investigated by the degradation of Rhodamine B (RhB) under ultraviolet light irradiation. The results show that Au–ZnO/graphene nanocomposites not only have optical absorptions in both UV and visible ranges, but also exhibit much enhanced photocatalytic performance compared to pure Au–ZnO hybrid nanocrystals. [ABSTRACT FROM AUTHOR]

Amorphous ZnSnO 3 double-shell and yolk-shell hollow microcubes were synthesized by calcination of their corresponding ZnSn(OH) 6 precursors pre-prepared through a facile chemical solution method in argon. The as-prepared amorphous ZnSnO 3 double-shell hollow microcubes have an average edge length of 1.6 μm. When used as the anode materials, amorphous ZnSnO 3 double-shell hollow microcubes (D-ZnSnO 3 ) reveal better electrochemical properties than ZnSnO 3 yolk-shell counterparts (Y-ZnSnO 3 ). D-ZnSnO 3 anodes can retain a high reversible capacity of 741 mA h g −1 after 50 cycles with a coulombic efficiency of 99% at 100 mA g −1 . The amorphous feature and unique box-in-box hollow architecture of D-ZnSnO 3 play a key role in their excellent electrochemical properties. [ABSTRACT FROM AUTHOR]

ZnO–ZnCo 2 O 4 hybrid hollow microspheres are successfully produced via an annealing process of the pre-fabricated zinc–cobalt citrate hollow microspheres in air. ZnO and ZnCo 2 O 4 have homogeneous distribution within the whole hollow microspheres. The gained hybrid hollow microspheres deliver outstanding lithium storage properties when utilized as the anode material in lithium ion batteries. A high reversible capacity of 1199 mA h g −1 can be retained after 200 cycles. The exceptional electrochemical properties of the hybrid hollow microspheres are ascribed to the synergetic effect between ZnO and ZnCo 2 O 4 nanoparticles, the catalytic effect of Co nanocrystals, the favorable hollow structures together with the nanometer-sized building blocks of hybrid microspheres. [ABSTRACT FROM AUTHOR]

ZnO/Ni/C composite hollow microspheres were synthesized by calcination of zinc–nickel citrate hollow microspheres at 500 °C for 2 h in argon. The composite hollow microspheres with an average diameter of 1.2 μm are made up of numerous nanoparticles with sizes ranging from 15 to 25 nm. When applied as the anode materials for lithium ion batteries, the composite hollow microspheres demonstrate excellent cycling stability. Compared to ZnO solid microspheres, the enhanced electrochemical properties of ZnO/Ni/C composites are attributed to the decoration of nickel and carbon as well as its unique hollow structures. ZnO/NiO/C composite hollow microspheres prepared by calcination of ZnO/Ni/C composites in air also reveal good lithium storage properties. [ABSTRACT FROM AUTHOR]

Highlights: [•] ZnO-C yolk-shell microspheres, hollow microspheres and solid microspheres are prepared. [•] Yolk-shell ZnO-C microspheres possess the best electrochemical properties when used as the anode materials for lithium-ion batteries. [•] The special yolk-shell structures and extra carbon support account for the enhanced electrochemical properties. [ABSTRACT FROM AUTHOR]