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In our work, the novel sparsely and compactly MoO3 nanoflowers were synthesized by a hydrothermal method assisted with polyvinyl pyrrolidone (PVP) and without any template, respectively. Through X-ray diffraction and scanning electron microscopy, we can confirm that we have prepared high purity MoO3 and can observe that both nanoflowers are formed by self-assembly of thin nanosheets. They have similar morphology, size and formation mechanism, but differ from pore size and quantity. Because of the above differences, sparsely MoO3 nanoflowers have a larger specific surface area and form more enclosed micro-reaction chambers that make it difficult for ethanol to escape. Allowing gas molecules to be more widely distributed among the sparsely sample surface and obtained fully reaction time. Thus, the gas sensor based on compactly MoO3 nanoflowers exhibits a better response and recovery characteristic. [ABSTRACT FROM AUTHOR]

Nanomaterials with three dimensional architectures frequently exhibit novel functional properties. In current work, a novel rutile TiO 3D nanoflowers with the powder partly agglomerating have been successfully synthesized via a facile hydrothermal route in the saturated sodium chloride solution. In addition, the effect of the solvent in hydrothermal process was preliminarily discussed on the basis of comparative experiments. Such an unexpected morphology provides a non-trivial behavior driven by the properties of partly agglomerating TiO nanoflowers in gas sensing. [ABSTRACT FROM AUTHOR]

Here we report a simple hydrothermal route for the preparation of CuO nano-flower which has been proved to exhibit good performances in gas-sensing. We concentrate on the microstructure and morphology of CuO by adjusting the reaction time length. Four different morphologies that formed a flower-like shape with a diameter of 1-3 µm were obtained. The CuO nanostructures were characterized in detail by means of X-ray diffraction and scanning electron microscopy and were apparently seen that they were composed of abundant aggregative nanobelts. The prepared CuO properties in gas-sensing were also measured in our experiments. In addition, a proper growth mechanism was proposed based on the results. Moreover, the CuO nano-flowers may resolve the difficulties in low-dimensional gas-sensing applications after more research having been conducted. [ABSTRACT FROM AUTHOR]

In this work, we reported successful synthesis of SnO nanocubes and nanospheres via a facile hydrothermal technique. The as-obtained SnO nanostructures have been characterized by X-ray diffraction and field-emission scanning electron microscopy. The formation mechanism of aforementioned SnO nanostructures has been proposed in detail, especially SnO nanaocubes, which has been systematically investigated by varying the reaction time and the surfactant SDS play a key role in growth process of nanocubes. Furthermore, the gas sensing properties of as-prepared SnO nanostructures have been tested towards ethanol. Interestingly, it is noted that gas sensing performance of nanocubes are superior to nanospheres, which certified that the gas sensing properties can be enhanced by controlling the morphologies and the SnO nanocubes maybe a promising candidate based materials in the fields of gas sensors. [ABSTRACT FROM AUTHOR]

We report the microstructures and gas sensing properties of two novel SnO nanorods prepared by hydrothermal method with the utilizing of cetyltrimethylammonium bromide and polyethylene glycol. The structures and morphologies of the dense and porous nanorods were characterized by means of powder X-ray diffraction and scanning electron microscopy. The gas sensing performances towards ethanol of the two samples were investigated. The results show that the porous SnO nanorods display excellent gas response to ethanol, indicating SnO as a potential gas sensing material for broad applications. [ABSTRACT FROM AUTHOR]

CuO nano-particles, nano-rods, nano-sheets and nano-flowers were synthesized by the hydrothermal routes with copper salts under different additions. The obtained samples were characterized by X-ray diffraction and scanning electron microscopy. We investigated the effects of precursors on the formation of CuO with different morphologies and proposed their possible formation mechanisms. In addition, the obtained CuO nano-flowers are found to show better sensing performances than the other three low-dimensional CuO nanostructures. Our results also demonstrate that gas sensing properties of nanocrystals can be significantly improved by tailoring shape and morphology of the nanocrystals. The CuO nano-flowers may hold substantial promise in low-dimensional gas-sensing applications. [ABSTRACT FROM AUTHOR]

Octahedral cuprous oxide has been synthesized by a simple hydrothermal method using copper sulphate and sodium hydroxide as raw materials in ethanol amine/distilled water mixed solution. The synthesized cuprous oxide powders were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy. XRD pattern exhibited that the nanocrystalline nature with cubic structure for the synthesized nanostructures. Analysis results reveal that pH value of solution plays an important role in the formation of octahedron shape for cuprous oxide. A probable formation mechanism of octahedral cuprous oxide is also proposed. [ABSTRACT FROM AUTHOR]

Rose-like CuO nanoflowers have been synthesized by polyvinylpyrrolidone K30 (PVP K30)-assisted hydrothermal method. Here, copper sulfate CuSO and sodium hydroxide NaOH were used as raw materials. The synthesized CuO powders were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). XRD pattern exhibited the nanocrystalline nature with cubic structure for the synthesized nanostructures. FESEM images indicated that the rose-like CuO nanostructures are composed of many nearly rectangular shape nanosheets in size of about 1-2 micrometers in width and length and approximate 50-60 nm in thickness. Analysis results reveal that PVP K30 plays a vital role in formation of rose-like CuO nanoflower in this work. The probable formation mechanism of rose-like CuO nanoflower was discussed. [ABSTRACT FROM AUTHOR]

Different morphologies of 3D SnO nanostructures, including sphere-like, net-like, and flower-like, have been successfully synthesised via a facile hydrothermal method. The products were characterized by X-ray diffraction and scanning electron microscopy. The possible growth mechanism of different SnO nanostructures was discussed in detail. We found that the citric acid and PEG play significant roles in synthesizing the flower-like and net-like nanostructures. Furthermore, the gas-sensing properties of the samples were investigated towards the reducing ethanol gas. The results indicate that the flower-like and net-like SnO show larger gas sensing properties than sphere-like SnO. [ABSTRACT FROM AUTHOR]

Anatase TiO nanoparticles and other three different morphologies of titanate nanostructures such as nanotubes, nanosheets and nanowires were successfully prepared by hydrothermal method. The structures and morphologies of the final products were characterized with field-emission scanning electron microscopy (FE-SEM). Phase analysis was carried out using X-ray diffraction (XRD). A novel formation mechanism from anatase TiO nanoparticles to titanate nanowires is proposed based on FE-SEM. The gas sensing properties to ethanol were also investigated. The results indicate that nanotubes, nanosheets, nanowires show much less resistance and larger response than nanoparticles. [ABSTRACT FROM AUTHOR]