Facile preparation of squarylium dye sensitized TiO2 nanoparticles and their enhanced visible-light photocatalytic activity

A squarylium dye, 1,3-bis[(3,3-dimethylindolin-2-ylidene)methyl] squaraine (ISQ) sensitized TiO2 nano-particles photocatalysts with different mass ratio of ISQ to TiO2 were facilely prepared by blending ISQ and TiO2 in ethanol solution. The resulting composite photocatalysts were characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectra (FT-IR) and UV-vis diffuse reflectance spectroscope (DRS). The visible light photocatalytic activities of ISQ sensitized TiO2 nanoparticles were evaluated using the degradation of methylene blue (MB) as a photodegradation target. The results showed that photo-response of the ISQ sensitized TiO2 nanoparticles were remarkably extended to visible-light region, and the ISQ dye sensitized TiO2 exhibited significantly enhanced photocatalytic activity under visible light irradiation. The maximum photocatalytic activity of the ISQ sensitized TiO2 was found at a composite photocatalyst (mass ratio of ISQ to TiO2 was 1: 3), and its degradation efficiency of MB reached approximately 98% in 2 h under visible light irradiation. Furthermore, a possible mechanism for the photocatalytic oxidative degradation was also proposed. (C) 2013 Elsevier B.V. All rights reserved.