TiO2 nanotube/ZnO nanorod/CdS on Ti mesh with three-dimensional array structure for photocatalytic degradation under visible light irradiation

摘要

The three-dimensional (3D) TiO2 nanotube arrays (TNTA) were prepared by electrochemical anodization of Ti mesh in a mixed electrolyte solution of (NH4)(2)SO4 and NH4F. Well-defined CdS-sensitized ZnO nanorod arrays (ZNRA/CdS) were successfully built on TNTA by the hydrothermal method and chemical bath deposition. The as-prepared samples were characterized by means of XRD, FESEM, and UV-Vis. The photocatalytic activities of the samples were evaluated by measuring the photodegradation of methylene blue (MB) in aqueous solution under visible light irradiation. The photocatalytic efficiencies for MB degradation were 49 and 60 % for Ti mesh/ZNRA/CdS and Ti mesh/TNTA/ZNRA/CdS after irradiation for 6 h, respectively. This can be attributed to the presence of TNTA at the bottom of a ZNRA/CdS composite, which provides a direct pathway for photoinjected electrons transferring along the photoanode to enhance charge-collection efficiency and consequently reduce electron-hole recombination. Furthermore, it can enlarge the practical applications range of TiO2 due to its 3D nanoarray structure with good light-harvesting ability and flexibility.