CdSe nanorod/TiO nanoparticle heterojunctions with enhanced solar- and visible-light photocatalytic activity.

CdSe nanorods (NRs) with an average length of ≈120 nm were prepared by a solvothermal process and associated to TiO nanoparticles (Aeroxide P25) by annealing at 300 °C for 1 h. The content of CdSe NRs in CdSe/TiO composites was varied from 0.5 to 5 wt %. The CdSe/TiO heterostructured materials were characterized by XRD, TEM, SEM, XPS, UV-visible spectroscopy and Raman spectroscopy. TEM images and XRD patterns show that CdSe NRs with wurtzite structure are associated to TiO particles. The UV-visible spectra demonstrate that the narrow bandgap of CdSe NRs serves to increase the photoresponse of CdSe/TiO composites until ≈725 nm. The CdSe (2 wt %)/TiO composite exhibits the highest photocatalytic activity for the degradation of rhodamine B in aqueous solution under simulated sunlight or visible light irradiation. The enhancement in photocatalytic activity likely originates from CdSe sensitization of TiO and the heterojunction between these materials which facilitates electron transfer from CdSe to TiO. Due to its high stability (up to ten reuses without any significant loss in activity), the CdSe/TiO heterostructured catalysts show high potential for real water decontamination.