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Sparsely and closely flower-like WO 3 ·H 2 O hierarchical architectures were successfully synthesized via a one-step hydrothermal process. The obtained samples are both WO 3 ·H 2 O nanoflowers assembled by ultrathin nanosheets with the thickness less than electron deletion layer. And the possible formation processed was proposed based on the comparative studies. Furthermore, gas sensing experiments demonstrated that the closely WO 3 ·H 2 O nanoflowers which possess numerous semi-closed spaces have a superior gas-sensing performance compared with the sparsely one. We believe this unique structure will critically enhance the gas sensing properties of WO 3 ·H 2 O nanomaterials. [ABSTRACT FROM AUTHOR]

Nanomaterials with hierarchical architectures consisting of two-dimensional nanostructures have attracted considerable attention for their potential applications in recent years. In current work, flake-flower NiO architectures self-assembled by aggregative nanosheets have been successfully synthesized via the hydrothermal route. It is notable that the NiO sensors exhibit excellent gas sensing performances owing to the open and well-defined structure as well as abundant micro reaction rooms built by two-dimensional ultrathin nanosheets, which are thinner than the thickness of electron depletion layer. Moreover, a possible growth mechanism for the interactions between PVP and Ni 2+ ions in the synthesis of the precursors Ni(OH) 2 and the novel morphology evolution of the NiO nanoflowers are proposed in detail. [ABSTRACT FROM AUTHOR]

Self-assembly of one-dimensional nanoscale building blocks into functional three-dimensional super-structures has attracted vast interests. In current work, novel NiO flower-like architectures have been successfully synthesized via a facile hydrothermal method and subsequent calcination. Notably, it has been observed that the sodium oxalate plays a vital role on the aggregation of needles and a novel growth mechanism of needle-flower NiO has been proposed in detail based on the experimental results. More importantly, it is noted that the gas sensing properties of the flower-like architectures are superior to needle-like structures on the basis of the investigation. Such a synthetic way may open up an avenue to tailor the morphologies of some other metal oxides and enhance their gas sensing performance. [ABSTRACT FROM AUTHOR]

Novel urchinlike hexagonal WO 3 microspheres have been fabricated by a facile hydrothermal method in the presence of K 2 SO 4 . Morphology analysis reveals that the as-synthesized WO 3 microstructures are assembled by numerous one-dimensional nanorods. Based on comparative studies, a possible formation mechanism is proposed in detail. What’s more, gas-sensing measurement indicates that the well-defined urchinelike WO 3 microspheres exhibit excellent gas sensing properties. [ABSTRACT FROM AUTHOR]

Monodisperse NiO hierarchical nanoflowers fabricated by nanobundles have been successfully synthesized under hydrothermal conditions followed by a calcination treatment. It is amazingly observed that the bundle-like nanoflowers possessed the emanative needle-like ends on the nanoscale, which was different from the previous 3D hierarchical architectures only fabricated by nanosheets, entire solid rod-like and emanative needle-like structures. Furthermore, based on the further experiments, the amount of ethylene glycol (EG, 99.5 wt%) play a key role on the formation of emanative needle-like ends and constructions of the 3D hierarchical flower-like architectures, and the relative formation mechanism was primarily discussed. Such an unexpected morphology may provide a non-trivial behavior driven by the properties of emanative needle-like ends and electron transformation continuity. [ABSTRACT FROM AUTHOR]

Nanomaterials with low-dimensional architectures frequently exhibit novel functional properties. In current work, NiO nanobelts with well-defined morphologies and uniform size have been successfully synthesized via a facile hydrothermal method. Furthermore, a novel growth mechanism of NiO nanobelts has been proposed in detail. Surprisingly, it is worth mentioning that the sodium oxalate is of great benefit to the formation of NiO one-dimensional nanostructures and plays a vital role on tailoring morphologies of nanobelts on the basis of further comparative experiments. Such a synthetic way may open up an avenue to prepare some other oxides. [ABSTRACT FROM AUTHOR]

Molybdenum trioxides (MoO 3 ) with flower-like hierarchical structure and distinct nanobelts have been synthesized via a hydrothermal method. A series of comparative experiments show that cetyltrimethyl ammonium bromide (CTAB) and HNO 3 have evident impact on forming the morphologies of MoO 3 . Interestingly, the add order of CTAB and HNO 3 can be also a determinant factor in the assemble process. This research is of great significance in the preparations, characterizations and applications of various 1D and 3D semiconductor metal oxides. The possible growth mechanism is also proposed. [ABSTRACT FROM AUTHOR]

Abstract: New morphologies often play a critical role in governing properties of nano-materials. Here, using hydrothermal method and reagents of sodium citrate and polyethylene glycol (PEG), we synthesize the ZnO nano-crystals and find that they exhibit hierarchical flower-like architectures assembled by nanosheets. Further comparative studies demonstrate that the sodium citrate assists a uniform growth of the nanosheets, and the PEG provides nucleation sites for the assembling of the nanosheets, both of which play a critical role in producing such unique flower-like architectures. Consequently, this sample is found to show excellent sensing performances to the target ethanol owing to its largest amount of petals, intervals, and pores. Such an unexpected morphology holds substantial promise for rendering ZnO as a potential gas-sensing material for a broad range of future sensor applications. [Copyright &y& Elsevier]