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Enhancing Photoactivity of TiO2(B)/Anatase Core–Shell Nanofibers by Selectively Doping Cerium Ions into the TiO2(B) Core

Authors

  • Prof. Dongjiang Yang,

    Corresponding author
    1. College of Chemistry, Chemical and Environmental Engineering, Laboratory of Fiber Materials and Modern Textile the Growing Base for State Key Laboratory, Qingdao University, Qingdao 266071 (P.R. China)
    2. Discipline of Chemistry, Queensland University of Technology, GPO Box 2434, Brisbane, QLD 4001 (Australia), Fax: (+61) 7-3138-1804
    • College of Chemistry, Chemical and Environmental Engineering, Laboratory of Fiber Materials and Modern Textile the Growing Base for State Key Laboratory, Qingdao University, Qingdao 266071 (P.R. China)
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  • Dr. Jian Zhao,

    1. Discipline of Chemistry, Queensland University of Technology, GPO Box 2434, Brisbane, QLD 4001 (Australia), Fax: (+61) 7-3138-1804
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  • Dr. Hongwei Liu,

    1. Discipline of Chemistry, Queensland University of Technology, GPO Box 2434, Brisbane, QLD 4001 (Australia), Fax: (+61) 7-3138-1804
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  • Dr. Zhanfeng Zheng,

    1. Discipline of Chemistry, Queensland University of Technology, GPO Box 2434, Brisbane, QLD 4001 (Australia), Fax: (+61) 7-3138-1804
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  • Dr. Moses O. Adebajo,

    1. Discipline of Chemistry, Queensland University of Technology, GPO Box 2434, Brisbane, QLD 4001 (Australia), Fax: (+61) 7-3138-1804
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  • Dr. Hongxia Wang,

    1. Discipline of Chemistry, Queensland University of Technology, GPO Box 2434, Brisbane, QLD 4001 (Australia), Fax: (+61) 7-3138-1804
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  • Prof. Xiaotang Liu,

    1. College of Sciences, South China Agricultural University, Guangzhou 510642 (P.R. China)
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  • Prof. Hongjie Zhang,

    1. Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022 (P.R. China)
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  • Prof. Jin-cai Zhao,

    Corresponding author
    1. Institute of Chemistry, The Chinese Academy of Science, Beijing 100080 (P.R. China)
    • Institute of Chemistry, The Chinese Academy of Science, Beijing 100080 (P.R. China)
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  • Prof. John Bell,

    1. Discipline of Chemistry, Queensland University of Technology, GPO Box 2434, Brisbane, QLD 4001 (Australia), Fax: (+61) 7-3138-1804
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  • Prof. Huaiyong Zhu

    Corresponding author
    1. Discipline of Chemistry, Queensland University of Technology, GPO Box 2434, Brisbane, QLD 4001 (Australia), Fax: (+61) 7-3138-1804
    • Discipline of Chemistry, Queensland University of Technology, GPO Box 2434, Brisbane, QLD 4001 (Australia), Fax: (+61) 7-3138-1804
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Abstract

Cerium ions (Ce3+) can be selectively doped into the TiO2(B) core of TiO2(B)/anatase core–shell nanofibers by means of a simple one-pot hydrothermal treatment of a starting material of hydrogen trititanate (H2Ti3O7) nanofibers. These Ce3+ ions (≈0.202 nm) are located on the (110) lattice planes of the TiO2(B) core in tunnels (width≈0.297 nm). The introduction of Ce3+ ions reduces the defects of the TiO2(B) core by inhibiting the faster growth of (110) lattice planes. More importantly, the redox potential of the Ce3+/Ce4+ couple (E°(Ce3+/Ce4+)=1.715 V versus the normal hydrogen electrode) is more negative than the valence band of TiO2(B). Therefore, once the Ce3+-doped nanofibers are irradiated by UV light, the doped Ce3+ ions—in close vicinity to the interface between the TiO2(B) core and anatase nanoshell—can efficiently trap the photogenerated holes. This facilitates the migration of holes from the anatase shell and leaves more photogenerated electrons in the anatase nanoshell, which results in a highly efficient separation of photogenerated charges in the anatase nanoshell. Hence, this enhanced charge-separation mechanism accelerates dye degradation and alcohol oxidation processes. The one-pot treatment doping strategy is also used to selectively dope other metal ions with variable oxidation states such as Co2+/3+ and Cu+/2+ ions. The doping substantially improves the photocatalytic activity of the mixed-phase nanofibers. In contrast, the doping of ions with an invariable oxidation state, such as Zn2+, Ca2+, or Mg2+, does not enhance the photoactivity of the mixed-phase nanofibers as the ions could not trap the photogenerated holes.

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