Visible light responsive titanium dioxide-cyclodextrin-fullerene composite with reduced charge recombination and enhanced photocatalytic activity

Titanium dioxide (TiO2)-fullerene (C-60) composite is prepared from TiO2 and beta-cylcodextrin (CD) encapsulated C-60 using the solar light irradiation. The absorption of the composite extends to the visible light region due to the charge transfer from CD and C-60 and TiO2. The composite shows reduced charge recombination compared to that of the bare TiO2 and TiO2/CD. The rate constant values for the photodegradation reactions of methylene blue and 4-chlorophenol (4-CP) are significantly higher (similar to 2-5 times) for the composites with 0.5 and 1.5 wt.% C-60 compared to that of the bare TiO2. Photocatalytic studies in the presence of scavengers reveal that the composites produce higher amount of reactive oxygen species (ROS). The enhanced photocatalytic activity of the composites is attributed to the visible light responsiveness, reduced charge recombination and increased formation of ROS. The photodegradation of 4-CP is significantly faster in the presence of the composite with 1.5 wt.% C-60 and is attributed to the synergistic effect of higher adsorption and increased ROS formation. The ROS formation by C-60 is possible because of the nonaggregated state of C-60 molecules in the composite and is assigned to the method which employs CD molecules to disperse C-60 in the composite. (C) 2014 Elsevier Ltd. All rights reserved..