ZnFe2O4/MWCNTs composite with enhanced photocatalytic activity under visible-light irradiation

Zinc ferrite/multi-walled carbon nanotubes (ZnFe2O4/MWCNTs) composite was prepared by a hydrothermal process and characterized by X-ray diffraction, transmission electron microscopy, and ultraviolet-visible diffusion reflectance spectroscopy. Compared with pure ZnFe2O4, the ZnFe2O4/MWCNTs composite exhibits stronger absorption in visible-light range and higher photocatalytic activity, with 99% degradation ratio of methylene blue after 6 h visible-light irradiation in the presence of H2O2. The enhanced photocatalytic activity is attributed to the strong interaction between ZnFe2O4 and MWCNTs which inhibits the recombination of photo-generated charge carriers, and the formation of highly active species (OH)-O-center dot on the surface of MWCNTs. Therefore, more radicals are formed for degradation of the dye. The enhancing mechanism of the photocatalytic activity of ZnFe2O4 in the presence of MWCNTs is also discussed. (C) 2010 Elsevier B.V. All rights reserved.