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Hierarchical 3D flower-like MoS 2 nanospheres with the diameter of about 300 nm were successfully synthesized via a facile hydrothermal process assisted with CTAB. And we found that CTAB played a vital role on the formation of MoS 2 architectures. As the concentration of CTAB increasing, MoS 2 nanopowders with sheet-like, flower-like, large size spherical morphologies were synthesized. And particle sizes of synthesized powders also increased. The optimum concentration of CTAB for the well-defined 3D hierarchical spherical morphology of MoS 2 was 6 g/L. In addition, a feasible formation mechanism of the morphology evolution was put forward in detail on the basis of the experimental results. The gas–sensing properties of flower-like MoS 2 nanospheres were tested. The result indicated that the sensor exhibited high response and selectivity towards NO 2, which may be related to the open and well-defined structures and the abundant micro reaction rooms assembled by ultrathin nanosheets. [ABSTRACT FROM AUTHOR]

3D hierarchical porous MoS 2 microspheres assembled by nanosheets were successfully fabricated via a facile yet efficient hydrothermal process using an assistance of CTAB as soft template which had significant effects on the final morphology of MoS 2 products. The possible formation mechanism of the harvested porous MoS 2 microspheres were preliminarily presented on the basis of the experimental results. Moreover, the gas sensing properties of the samples were investigated. The hierarchical porous MoS 2 microspheres are found to exhibit an excellent gas response capability, good response-recovery properties, reproducibility and selectivity, which provides further evidence that assistance CTAB is critical for governing the morphology and properties of the MoS 2 . [ABSTRACT FROM AUTHOR]

A facile hydrothermal route was developed for the preparation of well-aligned hierarchical flower-like NiO nanostructure with the assistance of SDS that served as a structure-directing agent as well as a capping agent in the process of aggregation and assembly. Notably, the NiO sensors exhibit enhanced gas-sensing performance towards ethanol, which could be explained in association with the ultrathin nanosheets that are close to Debye length (L D ) scale and thus get the majority carriers fully depleted due to the ionization of adsorbed oxygen, abundant effective gas diffusion paths as well as high surface-to-volume ratio to promote sufficient contact and reaction between the NiO sample and ethanol molecules, and numerous miniature reaction rooms assembled with nanosheets to make the test gas molecules stay long enough for completed gas-sensing reactions. Besides, a novel growth mechanism with the passage of reaction time was also proposed in detail. [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]

Nanoneedle-assembled hierarchical and nanosheet-assembled hierarchical NiO nanoflowers were successfully synthesized via a facile hydrothermal method and subsequent calcination. And we proposed their growth mechanisms and the influences on gas-sensing properties. The results indicated that the gas sensing properties of NiO nanocrystals can be dramatically enhanced by tailoring the nanoscale building blocks. In addition, it was surprisingly noticed that the nanoneedle-assembled hierarchical NiO structures exhibited quicker gas response and recovery than the nanosheet-assembled ones. While nanosheet-assembled hierarchical NiO nanoflowers demonstrated higher gas response towards ethanol. [ABSTRACT FROM AUTHOR]

Novel sparse-type and close-type NiO nanoflowers have been controllably synthesized via hydrothermal process assisted with CTAB and SDS, respectively. The sensing performance of the close-type NiO was superior to the other, which benefits from the following factors: In the close-type nanoflower, (1) the architecture is more porous and closer; (2) more nanojunctions between adjacent nanosheets are formed; (3) abundant micro reaction rooms are assembled by nanosheets; (4) the thickness of nanosheets are much smaller than twice Debye length. [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]