Engineering of Facets, Band Structure, and Gas-Sensing Properties of Hierarchical Sn2+-Doped SnO2 Nanostructures

Authors

  • Hongkang Wang,

    1. Department of Physics and Materials Science & Centre for Functional Photonics (CFP), City University of Hong Kong, Hong Kong SAR
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  • Kunpeng Dou,

    1. Department of Physics and Materials Science & Centre for Functional Photonics (CFP), City University of Hong Kong, Hong Kong SAR
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  • Wey Yang Teoh,

    1. Clean Energy and Nanotechnology (CLEAN) Laboratory, School of Energy and Environment, City University of Hong Kong, Hong Kong SAR
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  • Yawen Zhan,

    1. Department of Physics and Materials Science & Centre for Functional Photonics (CFP), City University of Hong Kong, Hong Kong SAR
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  • Tak Fu Hung,

    1. Department of Physics and Materials Science & Centre for Functional Photonics (CFP), City University of Hong Kong, Hong Kong SAR
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  • Feihu Zhang,

    1. Department of Chemistry, College of Science, Shanghai University, Shanghai 200444, P. R. China
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  • Jiaqiang Xu,

    1. Department of Chemistry, College of Science, Shanghai University, Shanghai 200444, P. R. China
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  • Ruiqin Zhang,

    Corresponding author
    1. Department of Physics and Materials Science & Centre for Functional Photonics (CFP), City University of Hong Kong, Hong Kong SAR
    • Department of Physics and Materials Science & Centre for Functional Photonics (CFP), City University of Hong Kong, Hong Kong SAR.
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  • Andrey L. Rogach

    Corresponding author
    1. Department of Physics and Materials Science & Centre for Functional Photonics (CFP), City University of Hong Kong, Hong Kong SAR
    • Department of Physics and Materials Science & Centre for Functional Photonics (CFP), City University of Hong Kong, Hong Kong SAR.
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Abstract

Hierarchical SnO2 nanoflowers, assembled from single-crystalline SnO2 nanosheets with high-index (11equation image) and (10equation image) facets exposed, are prepared via a hydrothermal method using sodium fluoride as the morphology controlling agent. Formation of the 3D hierarchical architecture comprising of SnO2 nanosheets takes place via Ostwald ripening mechanism, with the growth orientation regulated by the adsorbate fluorine species. The use of Sn(II) precursor results in simultaneous Sn2+ self-doping of SnO2 nanoflowers with tunable oxygen vacancy bandgap states. The latter further results in the shifting of semiconductor Fermi levels and extended absorption in the visible spectral range. With increased density of states of Sn2+-doped SnO2 selective facets, this gives rise to enhanced interfacial charge transfer, that is, high sensing response, and selectivity towards oxidizing NO2 gas. The better gas sensing performance over (10equation image) compared to (11equation image) faceted SnO2 nanostructures is elucidated by surface energetic calculations and Bader analyses. This work highlights the possibility of simultaneous engineering of surface energetics and electronic properties of SnO2 based materials.

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