The "cascade effect" of nano/micro hierarchical structure: A new concept for designing the high photoactivity materials - An example for TiO2

Po Chin Chen, Min Chiao Tsai, Min Han Yang, Ting Ting Chen, Huang Chin Chen, I. Chun Chang, Yi Chun Chang, Yu Liang Chen, I. Nan Lin, Hsin-Tien Chiu, Chi Young Lee*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

The chrysanthemum-like TiO2 (CT800) was synthesized. It exhibited excellent photoactivity, which greatly exceeded that of conventional P25. To discover the key factors that governed the photocatalytic properties, the specific reduction of Ag+ ions was carried out and EPR spectra of CT800 were obtained. Both an HADDF image and EDX mapping indicated that the Ag+ ions tended to be reduced close to the center of the micro matrix of CT800. Moreover, the EPR spectra strongly suggest that the excited electrons tended to migrate toward the center of the micro matrix, resulting from a multiple junction, cascade effect, which efficiently reduces the recombination of excited electrons and holes and greatly increases the photoactivity. Additionally, the special morphology of CT800 was responsible for the hot spots at the surface of nano sheets and then contributing to its outstanding photocatalytic activity. Furthermore, the unidirectional electron transfer, because of the cascade effect, by materials of different sizes provides a new avenue for the design of electronic and photoelectrochemical devices.

Original languageEnglish
Pages (from-to)752-760
Number of pages9
JournalApplied Catalysis B: Environmental
Volume142-143
DOIs
StatePublished - 1 Oct 2013

Keywords

  • Charge separation
  • Hetero-junction
  • Hierarchical structure
  • Photocatalyst
  • Titanium dioxide

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