Search

In this paper, WO 3 ·H 2 O with different nanostructures from 0D to 3D were successfully synthesized via a simple yet cost-effective hydrothermal method with the assistance of surfactants. The structures and morphologies of products were investigated by XRD and SEM. Besides, we systematically explained the evolution process and formation mechanisms of different WO 3 ·H 2 O morphologies. It is noted that both the kinds and amounts of surfactants strongly affect the formation of WO 3 ·H 2 O crystals, as reflected in the tailoring of WO 3 ·H 2 O morphologies. Furthermore, the gas sensing performance of the as-prepared samples towards methanol was also investigated. 3D flower-like hierarchical architecture displayed outstanding response to target gas among the four samples. We hoped our results could be of great benefit to further investigations of synthesizing different dimensional WO 3 ·H 2 O nanostructures and their gas sensing applications. [ABSTRACT FROM AUTHOR]

Abstract: WO3 H2O with different morphologies were synthesized through hydrothermal method by adding different surfactants. The effect of surfactants on tailing morphology was investigated through XRD and SEM analyses in detail and the possible formation mechanism was discussed. Furthermore, the gas-sensing performances of obtained samples to ethanol were investigated. The results revealed that the WO3 H2O with the hierarchical architectures assembled by nanosheets shows the highest response to ethanol among four kinds of the nanostructures WO3. These results on the preparation, mechanism and gas sensing properties of WO3 H2O nanostructures hold great potential for the syntheses of oxide materials with novel nanostructures and their applications. [Copyright &y& Elsevier]

Abstract: We successfully synthesized variant hierarchical assembled flower-like SnO2 via a simple hydrothermal technique and subsequent calcination. The structures and morphologies of the 3D nanostructures were investigated by means of powder X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). The formation mechanism of these materials were proposed in detail. The gas-sensing performances of the as-prepared SnO2 were investigated towards ethanol. It is noted that the flower-sheet SnO2 sensor displayed particular response to the target gas, rendering SnO2 as a potential gas-sensing material for a broad range of future sensor applications. [Copyright &y& Elsevier]

We successfully synthesized MoO 3 hierarchical structures assembled with nanofibers and nanosheets via a hydrothermal method assisted with hexadecyl trimethyl ammonium bromide (CTAB) and polyvinyl pyrrolidone (PVP), respectively. Then, we characterized the structure and morphology of the as-synthesized samples by X-ray diffraction and scanning electron microscopy. We analyzed the formation process of the two structures and verified the effects of different dimensionality assembly units on their gas-sensing properties through gas sensing experiments. Remarkably, nanosheet-assembled hierarchical MoO 3 structures, which possess abundant semi-closed microreaction spaces, exhibited an enhanced gas response. The gas response (the ratio of test voltage in the air to test voltage in the target gas) of a nanosheet-assembled MoO 3 based-sensor to 400 ppm ethanol reached 32 at an operating temperature of 300 °C. While nanofiber-assembled hierarchical structures showed a shorter response (3.2s) and recovery time (2.4s), which was due to the faster gas and electronic diffusion rate of the nanofibers. MoO 3 hierarchical structures assembled by nanofibers and nanosheets have been synthesized under hydrothermal conditions assisted with CTAB and PVP, respectively. Nanofiber-assembled hierarchical MoO 3 structures demonstrate less response and recovery time than the other. However, sensors based on nanosheet-assembled structures exhibit a higher gas response. The differences in the above properties can be attributed to their different dimensionality assembly units. Image 1 [ABSTRACT FROM AUTHOR]

Abstract: ZnO nanocrystals with various morphologies are synthesized via a simple and facile HMT assisted hydrothermal process. Here, HMT is introduced as a structure directing and assembling agent to controllable synthesis of ZnO architectures and the concentration of HMT play a critical role in producing such different ZnO morphologies. We find that the sandglass-like ZnO exhibit excellent sensing performances to the target ethanol gas owing to its largest amount of Zn-terminated ZnO (0001) polar surfaces, which can easily adsorb more oxygen species on the surface and therefore improve the gas-sensing performances of ZnO. Such an unexpected morphology holds substantial promise for rendering ZnO as a potential gas-sensing material for future sensor applications. [Copyright &y& Elsevier]