Synthesis of ZnO nanorod grafted TiO2 nanotube 3-D arrayed heterostructure as supporting platform for nanoparticle deposition

Grafting one-dimensional semiconductor nanostructures inside arrayed nanotubes of another semiconductor to form network heteroarchitectures is believed to improve photocatalytic activity on the bases of an enhanced separation of photoexcited electron-hole pairs and an enlarged surface area for light absorption and chemical reactions. Thus in this study, single-crystalline ZnO nanorod grafted anatase TiO2 nanotube three-dimensional arrayed heterostructures were synthesized via a simple solution process and acted as supporting platforms for nanoparticle deposition. The lattice orientations of the ZnO nanorods and TiO2 nanotubes were examined and suggested that the rods heterogeneously nucleated on the tubes and grew along a [002] direction following a structural correlation ZnO (100)//TiO2 (103). Silver nanoparticles were further deposited on the platforms to compose TiO2/ZnO/Ag multi-junction heterostructures which exhibited much superior photocatalytic activity than a conventional TiO2 nanotube array did.