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Abstract In this work, hollow MoO 3 microcages were triumphantly synthesized using a facile hydrothermal method without any template, and a possible growth mechanism of this microstructure arising from the co-effect of inside-out Ostward-ripening mechanism and the acidic etching was speculated. Subsequently, gas sensor based on such MoO 3 with hollow characteristic was fabricated to investigate the gas-sensing properties for ethanol as compared to solid MoO 3 polyhedrons. It was found that the hollow cages exhibited lager ethanol gas response than that of solid polyhedrons. The enhanced sensing behavior may originate from its unique hollow structures, leading to sufficient sensing reaction on the surface as well as abundant gas diffusion. Graphical abstract The hollow MoO 3 microcages were successfully synthesized via a simple hydrothermal method without any template. Such hollow structure based sensor presented enhanced gas response to ethanol than that of solid MoO 3 polyhedrons based sensor. The hollow nature led to sufficient sensing reaction on the surface as well as abundant gas diffusion. Image 1 Highlights • Hollow MoO 3 microcages were successfully synthesized. • The gas sensor based on the MoO 3 presented enhanced gas response to ethanol. • The hollow structure of the MoO 3 cages enhanced surface sensing reaction. [ABSTRACT FROM AUTHOR]

Herein, a novel hierarchical cactus-like WO 3 -SnO 2 nanocomposite was synthesized by a one-step hydrothermal route. It was a surprise to find that such nanostructure consisting of diminutive SnO 2 nanospheres decorated bulky WO 3 nanosphere exhibited a high gas response and fast response-recovery speed towards acetone, mainly attributed to their synergetic effect as well as the heterojunction at the interface between the bulky WO 3 nanosphere and diminutive SnO 2 nanosphere, resulting in adequate surface adsorption and efficient electron transport. [ABSTRACT FROM AUTHOR]

In this study, the hollow MoO 3 microcages were successfully synthesized using a one-step hydrothermal route, and their gas-sensing properties towards ethanol were further investigated. It was found that such MoO 3 microcages possessed excellent ethanol gas response, which benefited from their unique hollow structure with a less stacking aggregation, offering sufficient pathways for gas diffusion as well as abundant adsorption sites for surface chemical reaction. [ABSTRACT FROM AUTHOR]

ZnO nanorods and nanosheets were synthesized via a facile hydrothermal route, and their gas sensing properties were tested to figure out the effect of surface morphologies on gas sensing performance. It was surprisely found that the ZnO nanorods exhibit quicker response and recovery speed towards ethanol, which may be ascribed to the better conductivity and lower potential barrier, whereas the nanosheets display larger ethanol gas response owing to its higher specific surface area. [ABSTRACT FROM AUTHOR]

Hollow spheres are usually fabricated by hard template methods or soft template methods with soft surfactants, which is quiet tedious and time-consuming. In this paper, NiO hollow spheres with fluffy surface were successfully synthesized by a facile hydrothermal method and subsequent calcination, where bubbles acted as the template. NiO hollow spheres exhibited excellent gas sensing performances, which results from its hollow structure and high specific surface area. In addition, a possible evolution mechanism of NiO hollow spheres was proposed based on experimental results. [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]

In this article, a sealed nanotube of ZnO was successfully obtained by a simple hydrothermal technique, which employed Hexamethylene tetramine (HMT) and Fluorinion (F−) as the active agents. The rod-like nanotubes structures were observed through field-emission scanning electron microscopy. The high-resolution transmission electron microscope exhibited a shell-enclosed nanotube structures. On the basis of experimental observations, including temperature, pH of the solution and acting agents, a growth mechanism was proposed. The as-prepared nanostructures showed excellent gas sensitivities to different gases (ethanol, ammonia gas, formaldehyde gas) with a quite low concentration respectively. [ABSTRACT FROM AUTHOR]