One-Step Fabrication of CdS Nanoparticle-Sensitized TiO2 Nanotube Arrays via Electrodeposition

CdS nanoparticle-sensitized TiO2 (CdS-TiO2) nanotube arrays are synthesized with a facile one-step electrodeposition technique. In these composited nanostructures, CdS nanoparticles uniformly distribute in the TiO2 nanotubes and partially embed in the shell of TiO2 nanotubes. These structures effectively prevent CdS nanoparticles assembling or clogging the nanotubes and improve the contact area between CdS nanoparticles and the TiO2 shells. Furthermore, the size and distribution density of CdS nanoparticles can be tuned easily by controlling the concentration of electrolyte. Coupling TiO2 nanotubes with CdS nanoparticles extends the optical absorption from ultraviolet into the visible-light region up to 580 nm. An 11-fold enhancement in photoelectrochemical (PEC) activity is observed for CdS-TiO2 nanotube arrays compared with plain TiO2 nanotube arrays. This unique method is also suitable for the synthesis of other narrow band gap semiconductor-sensitized TiO2 nanotubes.