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Flower-like ZnO microstrucutures (ZMFs) self-assembled by nanosheets were fabricated by a simple template-free hydrothermal method, and the nanosheets were observed with a great many of mesopores. Without adding NaOH, sphere-like ZnO microstrucutures (ZMSs) which were covered by nanosheets were obtained. Subsequently, according to the characterization of SEM and TEM for ZMFs nanosheets, the possible formation mechanisms and simulation of ZMFs were discussed. The novel ZMFs presented numerous mesopores of size around 6 nm and high BET specific area (about 36.886 m/g) which contributed to its high gas-sensing performance. In comparison with the ZMSs-based sensor, the ZMFs-based sensor displayed excellent gas-sensing performance to the ethanol gas with high sensitivity of nearly 35 at the concentration of 250 ppm. [ABSTRACT FROM AUTHOR]

We have successfully reported a new diamond-like morphology of zinc oxide (ZnO) structures via a simple hydrothermal method and discussed its probable growth mechanism. Compared with other morphologies of ZnO structures (microrods and nanosheets), nanodiamonds have excellent gas-sensing property owning to its large specific surface area, holding the perfect promise for ZnO powders as underlying gas-sensing materials. Furthermore, the as-prepared nanosheets assisted with the sodium citrate as an additive were found to show better gas-sensing property due to the smaller size than microrods. We found the positive role of the sodium citrate and reaction time in the growth of nanosheets and nanodiamonds respectively and the corresponding influences on growth mechanism were 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]

Regular hexagonal embedded ZnO nanorods were successfully prepared by a simple hydrothermal method. The addition of urea as a homogeneous precursor was found to play a vital role in the embedding of secondary nanorods. The nanostructures were characterized by XRD, SEM, and EDS. The gas-sensing properties of secondary grown embedded nanorods were reported for formaldehyde, ethanol, methanol, acetone, and ammonia at different concentrations and temperatures. A higher response and greater selectivity toward formaldehyde than other gases was observed. A sharp response with the best recovery time was achieved at an optimum temperature of 200 °C. [ABSTRACT FROM AUTHOR]