Photocatalytic oxidation of organic dyes with visible-light-driven codoped TiO2 photocatalysts |
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Authors: | Dongfang Zhang and Fanbin Zeng |
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Institution: | (1) School of Materials and Chemical Engineering, Jiangxi University of Science and Technology, 341000 Ganzhou, People’s Republic of China;(2) Department of Chemistry, The Center of Novel Functional Molecules, and Environmental Science Programme, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China |
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Abstract: | A novel copper (II) and zinc (II) codoped TiO2 photocatalyst was synthesized by a modified sol-gel method using titanium (IV) isopropoxide, Zn(NO3)2 · 6H2O and copper(Il) nitrate as precursors. The samples were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy
(DRS) and photo-luminescence spectra (PL). The XRD results showed undoped and Zn, Cu-codoped TiO2 nanoparticles mainly including anatase phase and a tiny amount of Zn- and Cu-oxides exist in the mixed system, which is attributed
to the decomposition of copper and zinc nitrates in the TiO2 gel to form CuO and ZnO and randomly dispersed on the TiO2 surface. On the basis of the optical characterization results, we found that the codoping of copper (II) and zinc (II) resulted
a red shift of adsorption and lower recombination probability between electrons and holes, which were the reasons for high
photocatalytic activity of Zn, Cu-codoped TiO2 nanoparticles under visible light (λ > 400 nm). The photocatalytic activity of samples was tested for degradation of methyl
orange (MO) in solutions. The results indicated that the visible-light driven capability of the codoped catalyst were much
higher than that of the pure TiO2 catalyst under visible irradiation. Because of the synergetic effect of copper (II) and zinc (II) element, the Zn, Cu-codoped
TiO2 catalyst will show higher quantum yield and enhance absorption of visible light. In the end, a key mechanism was proposed
in order to account for the enhanced activity. |
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