Distinct visible-light response of composite films with CdS electrodeposited on TiO2 nanorod and nanotube arrays

Thorough infiltration of CdS nanoparticles into spaces of titania nanorod and nanotube arrays was achieved by an ac electrodeposition technique to construct composite films of CdS over titania. The substrate affected not only the electrodeposition rate but also the oriented growth of CdS. A photocurrent much larger than the simple summation of those arising from the two component layers of CdS and titania was detected for both composite films under visible-light illumination. Such an enhancement in the photocurrent was even more prominent for the composite film based on the titania nanorod arrays, which was contributed to the higher charge separation rate arising from the nearly single-crystalline nanorods when compared with the polycrystalline nanotubes.