CdS/ZnO Core/Shell Nanowire-Built Films for Enhanced Photodetecting and Optoelectronic Gas-Sensing Applications

Authors

  • Zheng Yang,

    1. Laboratory of Environmental Science and Technology Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi, China
    2. University of the Chinese Academy of Sciences, Beijing, China
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  • Linjuan Guo,

    1. Laboratory of Environmental Science and Technology Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi, China
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  • Baiyi Zu,

    Corresponding author
    1. Laboratory of Environmental Science and Technology Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi, China
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  • Yanan Guo,

    1. Laboratory of Environmental Science and Technology Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi, China
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  • Tao Xu,

    1. Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, Illinois, USA
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  • Xincun Dou

    Corresponding author
    1. Laboratory of Environmental Science and Technology Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi, China
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Abstract

Uniform CdS/ZnO core/shell nanowires are hydrothermally synthesized using a two-step process and assembled into a photodetector and a NO2 optoelectronic sensor for the first time. The corresponding photodetector exhibits a fast, reversible, and stable optoelectronic response with a rise time of ∼26 ms, a decay time of ∼2.1 ms and a stability of over 5 months. The remarkable photosensitivity and fast photoresponse are attributed to the formation of a heterojunction structure between CdS and ZnO, which greatly inhibits the recombination of photoinduced electrons and holes. The CdS/ZnO core/shell nanowires also show an excellent visible-light-activated gas sensing performance towards ppb-level NO2 at room temperature. The responses range from 6.7% to 337% toward NO2 concentrations of 5 to 1000 ppb. It is found that the sensitivity of the NO2 sensor is dependent on the illuminated light intensity with a maximum value at 0.68 mW/cm2. The sensing mechanisms of the CdS/ZnO nanowires under visible-light irradiation and the influence of light intensity are also discussed. The present CdS/ZnO core/shell nanowire not only benefits the fabrication of efficient photodetectors, but also makes the instant, optically controlled sensing of ppb-level NO2 gas possible.

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