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Title: Lattice distortion mechanism study of TiO{sub 2} nanoparticles during photocatalysis degradation and reactivation

In this paper, the photocatalytic process of TiO{sub 2} (P25) is directly characterized by using a positron annihilation lifetime spectroscopy (PALS), high-resolution transmission electron microscopy (HRTEM), Photoluminescence spectroscopy (PL) and UV Raman spectroscopy (Raman). The experimental results reveal that: 1) From PALS measurements, because τ{sub 1} and τ{sub 2} values and their intensity (I{sub 1} and I{sub 2}) assigned to the different size and amounts of defects, respectively, their variations indicate the formation of different types and amounts of defects during the absorption and degradation. 2) HRTEM observations show that the lattice images become partly blurring when the methylene blue is fully degradated, and clear again after exposed in the air for 30 days. According to the results, we propose a mechanism that the lattice distortion induces the defects as electron capture sites and provides energy for improving photocatalytic process. Meanwhile, the lattice distortion relaxation after exposing in the air for 30 days perfectly explains the gradual deactivation of TiO{sub 2}, because the smaller vacancy defects grow and agglomerate through the several photocatalytic processes. The instrumental PL and Raman are also used to analyze the samples and approved the results of PALS and HRTEM.
Authors:
; ; ; ;  [1] ;  [1] ;  [2]
  1. School of Physics and Technology, Hubei Nuclear Solid Physics Key Laboratory and MOE Key Laboratory of Artificial Micro- and Nano-structures, Wuhan University, Wuhan 430072 (China)
  2. (China)
Publication Date:
OSTI Identifier:
22488567
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Advances; Journal Volume: 5; Journal Issue: 5; Other Information: (c) 2015 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY; ABSORPTION; DEACTIVATION; DEFECTS; ELECTRON CAPTURE; IODINE; METHYLENE BLUE; NANOPARTICLES; PHOTOCATALYSIS; PHOTOLUMINESCENCE; POSITRONS; RAMAN SPECTROSCOPY; TITANIUM OXIDES; TRANSMISSION ELECTRON MICROSCOPY