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

Titanium dioxide (TiO2)–fullerene (C60) composite is prepared from TiO2 and β-cylcodextrin (CD) encapsulated C60 using the solar light irradiation. The absorption of the composite extends to the visible light region due to the charge transfer from CD and C60 to 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 (∼2–5 times) for the composites with 0.5 and 1.5 wt.% C60 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.% C60 and is attributed to the synergistic effect of higher adsorption and increased ROS formation. The ROS formation by C60 is possible because of the non-aggregated state of C60 molecules in the composite and is assigned to the method which employs CD molecules to disperse C60 in the composite.