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