Squaraine dye sensitized TiO2 nanocomposites with enhanced visible-light photocatalytic activity

A novel 1,3-bis(N-3H-3,3-dimethyl-2-methylene indolenine) squaraine dye (ISQ) sensitized TiO2 nanocomposites (ISQ/TiO2) were facilely prepared by mixing the solution of ISQ and TiO2 nanoparticle suspension in ethanol. The crystal structure, morphology and UV–vis diffuse reflectance spectroscopy of ISQ/TiO2 nanocomposites were analyzed. The XRD results showed that the synthesized ISQ/TiO2 nanocomposites were mixture of anatase and rutile crystals. The photocatalytic activity of ISQ/TiO2 nanocomposites was investigated by degrading methylene blue (MB) under visible-light irradiation (λ>400 nm). The photo-response of the ISQ/TiO2 nanocomposites was remarkably extended to visible-light region, and the photocatalytic activity of the ISQ/TiO2 nanocomposites was significantly enhanced. The photodegradation rate of MB for the ISQ/TiO2 nanocomposites reached approximately 98% after 2 h of visible-light irradiation. Furthermore, ISQ/TiO2 nanocomposites showed excellent photocatalytic stability after 5 successive cycles under visible-light.

► ISQ/TiO2 nanocomposites exhibited significantly enhanced visible-light activity.
► ISQ/TiO2 nanocomposites showed remarkable visible-light photocatalytic activity.
► ISQ/TiO2 nanocomposites exhibited excellent photocatalytic stability.