Improvement of photocatalytic activity of TiO2 nanoparticles on selectively reconstructed layered double hydroxide

Supported TiO2 nanoparticles have been successfully fabricated by selective reconstruction of a Cu2+, Mg2+, Al3+, Ti4+-containing layered double hydroxide (CuMgAlTi-LDH) precursor, synthesized by coprecipitation, through calcination and rehydration process. A systematic investigation of the structural characterization and the photodegradation tests of methylene blue (MB) dye molecules from solution under both UV and visible light irradiation for the resulting TiO2/CuMgAl-RLDH sample were carried out. Anatase-type TiO2 nanoparticles are found to be homogeneously distributed on the surface of the selectively reconstructed CuMgAl-RLDH support. And the direct evidence for the surface TiO2/LDH heterojunction formed on CuMgAl-RLDH is presented. For MB photodegradation under UV light or visible light illumination. TiO2/CuMgAl-RLDH sample has superior photocatalytic properties to the rehydrated single phase R-TiO2, the physical mixture of R-TiO2 and CuMgAl-RLDH, the composite CuTi/MgAl-RLDH synthesized by the rehydration of mixture of MgAl-MMO and CuTi-MMO, and the TiO2/MgAl-RLDH prepared under the same procedure as TiO2/CuMgAl-RLDH without containing Cu ions. The skeleton Cu2+ ions dispersed in the mainlayer of CuMgAl-RLDH support can enable the photocatalytic activity for MB photodegradation. The TiO2/LDH heterojunction nanostructure is proposed to contribute the efficient spatial separation between the photogenerated electrons and holes, which can concomitantly improve the photocatalytic activity. Our method provides a novel approach to fabricate new modes of load-type doped semiconductor photocatalysts which are both active under illumination by UV and visible light. (C) 2011 Elsevier B.V. All rights reserved.