Hierarchical TiO2/CdS "spindle-like" composite with high photodegradation and antibacterial capability under visible light irradiation

Novel hierarchical TiO2/CdS "spindle-like" composites with uniform distribution of CdS nanocrystals on nanoporous TiO2 mesocrystals were successfully prepared by hydrothermal and hot-injection methods. In this work, the optimal mass ratio of Ti/Cd is determined to be 2 of as-synthesized TiO2/CdS composites. This TiO2/CdS composite exhibits excellent photocatalytic activity in the degradation of Rhodamine B (RhB) and photocatalytic reaction constant is 10 times higher than that of TiO2, 3.5 times higher than that of CdS and higher than other TiO2/CdS composites with different amount of Ti/Cd mass ratio. In addition, TiO2/CdS with optimal amount of CdS kills 99.9% of Escherichia coli in 10 min under visible-light irradiation, which shows significant higher efficiency than pure TiO2, CdS and other TiO2/CdS composites. The excellent performances of this hierarchical composite are ascribed to its outstanding properties, including large specific surface area (BET), high crystallinity of oriented single-crystal-like nanoporous TiO2 mesocrystals for charge transfer, retarded recombination of photogenerated electron-hole pairs via isolating electrons and holes in two different materials, and extended photo response of this hierarchical composite to the visible region. Considering all these superior properties and abilities, this hierarchical TiO2/CdS "spindle-like" composite will show great potential for applications in the water purification field. (C) 2012 Elsevier B.V. All rights reserved.