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Enhancing Photoactivity of TiO 2 (B)/Anatase Core–Shell Nanofibers by Selectively Doping Cerium Ions into the TiO 2 (B) Core
Author(s) -
Yang Dongjiang,
Zhao Jian,
Liu Hongwei,
Zheng Zhanfeng,
Adebajo Moses O.,
Wang Hongxia,
Liu Xiaotang,
Zhang Hongjie,
Zhao Jincai,
Bell John,
Zhu Huaiyong
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201202719
Subject(s) - anatase , nanoshell , materials science , cerium , photocatalysis , doping , ion , nanofiber , nanotechnology , chemical engineering , inorganic chemistry , nanoparticle , chemistry , catalysis , optoelectronics , biochemistry , organic chemistry , engineering , metallurgy
Cerium ions (Ce 3+) can be selectively doped into the TiO 2 (B) core of TiO 2 (B)/anatase core–shell nanofibers by means of a simple one‐pot hydrothermal treatment of a starting material of hydrogen trititanate (H 2 Ti 3 O 7 ) nanofibers. These Ce 3+ ions (≈0.202 nm) are located on the (110) lattice planes of the TiO 2 (B) core in tunnels (width≈0.297 nm). The introduction of Ce 3+ ions reduces the defects of the TiO 2 (B) core by inhibiting the faster growth of (110) lattice planes. More importantly, the redox potential of the Ce 3+ /Ce 4+ couple ( E °(Ce 3+ /Ce 4+ )=1.715 V versus the normal hydrogen electrode) is more negative than the valence band of TiO 2 (B). Therefore, once the Ce 3+ ‐doped nanofibers are irradiated by UV light, the doped Ce 3+ ions—in close vicinity to the interface between the TiO 2 (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 Co 2+/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 Zn 2+ , Ca 2+ , or Mg 2+ , does not enhance the photoactivity of the mixed‐phase nanofibers as the ions could not trap the photogenerated holes.