Browsing by Author "Tsai, Ju-Heng"

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Controlled synthesis and CO sensing potentials of size-tunable highly-uniform mesoporous Co3O4 nanospheres
(2020-03-05)
Chen, Kuan-Wei
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Tsai, Ju-Heng
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Chen, Chun-Hua
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材料科學與工程學系
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Department of Materials Science and Engineering
A series of highly-uniform and mesoporous Co3O4 nanospheres comprising porously-assembled tiny building blocks, and more importantly, with widely tunable sizes from 50 nm up to 500 nm were successfully synthesized for the first time via single facile polyol approach. The crucial synthesizing factors including molecular weight and concentrations of polyvinylpyrrolidone, the fraction of cobalt precursor, and the subsequent calcination temperature and time were systematically varied over a very wide range for extensively understanding their effects on growth mechanisms, uniformity and particularly the minimum assembled size. The present unique mesoporous nanoassemblies evidently lead to not only a higher surface-to-volume ratio for a variety of potential applications but a lower operating temperature for CO sensing compared with that reported for a variety of intrinsic or heterogeneous Co3O4 nanostructures. (C) 2019 Elsevier B.V. All rights reserved.
NiO functionalized Co3O4 hetero-nanocomposites with a novel apple-like architecture for CO gas sensing applications
(2019-11-15)
Chen, Kuan-Wei
;
Tsai, Ju-Heng
;
Chen, Chun-Hua
;
材料科學與工程學系
;
Department of Materials Science and Engineering
An innovative NiO functionalized Co3O4 hetero-nanocomposite exhibiting an unusual apple-like architecture has been successfully fabricated via a facile two-step chemical route for CO gas sensing applications. The unique mimetic morphology constructed by spike-like NiO nanobundles with sharp tips planted on the surface of the preformed extremely porous Co3O4 nanospheres not only creates specific structural advantages but, more importantly, induces chemical activation required for gas sensing. Higher sensitivity and lower operating temperature are thus obtained for the present NiO-Co3O4 hetero-nanocomposite in comparison with those for the bare Co3O4 nanospheres and also for most reported intrinsic or heterogeneous Co3O4 nano-oxides. (C) 2019 Elsevier B.V. All rights reserved.