Surfactant-free synthesis of 3D hierarchical flower-like NiO nanostructures with enhanced ethanol-sensing performance
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Surfactant-free synthesis of 3D hierarchical flower-like NiO nanostructures with enhanced ethanol-sensing performance Shixiu Cao1,* 1
, Tao Han1, and Lingling Peng1
Research Institute for New Material Technology, Chongqing University of Arts and Science, Chongqing 402160, China
Received: 16 June 2020
ABSTRACT
Accepted: 17 August 2020
Different morphologies hierarchical flower-like Nickel oxide nanostructures were fabricated by changing the volume of ammonia (Va = 1, 4, and 8 ml) under a template-free and low-cost hydrothermal method and subsequent calcinations. The nanoflowers were composed of two-dimensional (2D) nanosheets. The sensor based on the samples of Va = 8 exhibited the most excellent gassensing performance to ethanol. Moreover, a possible growth mechanisms were also proposed. The facile preparation method and the improved properties derived from the three-dimensional structures are significant in the synthesis and future applications of functional nanomaterials.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
1 Introduction Nickel oxide (NiO) is a multifunctional p-type semiconductor with a wide bandgap (Eg = 3.6–4.0 eV). NiO nanomaterials were attractive materials for the potential applications in the fields of catalyst [1–4], battery cathode [5], magnetic material [6], gas sensor [7–17], and so forth. Thereinto, a broad attention has been paid on the gas sensors based on NiO nanomaterials, owing to its fast response, good stability, high sensitivity, and low cost. It is generally known that the size and morphology of the materials can impact its gas-sensing properties. The nanoflowers, nanosheets, nanoparticles, nanofilms, nanowires, and nanosheets have been widely studied due to excellent gas-sensing properties [7–17]. Three-dimensional (3D) nanostructures have captured a great deal of
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https://doi.org/10.1007/s10854-020-04283-w
attentions owing to their high surface-to-volume ratio and broad internal contact area, which contribute to sufficient diffusion path and enhanced reactive sites [7–11, 18, 19]. NiO nanostructures have been synthesized by many methods, such as sol–gel method, chemical precipitation method, electrochemical deposition techniques, and microwave solvothermal method. But, due to environment friendly, low cost and high product purity, the hydrothermal method may be a promising method [20–22]. In the work, we report a simple and template-free hydrothermal method for the fabrication of the flower-like NiO nanomaterials. The 3D NiO nanostructures exhibited outstanding gas-sensing performance to ethanol. The possible formation mechanisms were also discussed. This work may
J Mater Sci: Mater Electron
open a new way to design and prepare other more metallic oxides.
2 Experimental 2.1 Synthesis of samples All chemical reagents used were of analytical purity. Firstly, urea (10 mmol) and nickel acetate (1 mmol) were dissolved in 5 ml deionized water, respectively. Then the urea solution was added into t
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