Photosensitization of TiO₂ Nanostructures with CdS Quantum Dots: Particulate versus Tubular Support Architectures

TiO 2 nanotube arrays and particulate films are modified with CdS quantum dots with an aim to tune the response of the photoelectrochemical cell in the visible region. The method of successive ionic layer adsorption and reaction facilitates size control of CdS quantum dots. These CdS nanocrystals, upon excitation with visible light, inject electrons into the TiO 2 nanotubes and particles and thus enable their use as photosensitive electrodes. Maximum incident photon to charge carrier efficiency (IPCE) values of 55% and 26% are observed for CdS sensitized TiO 2 nanotube and nanoparticulate architectures respectively. The nearly doubling of IPCE observed with the TiO 2 nanotube architecture is attributed to the increased efficiency of charge separation and transport of electrons.