CdS Decorated Titania Nanotube Arrays by Ultrasonic Assistance and Covered with ZnO Film: Enhanced Transient Photoelectric Response and Stability

Firmly-structured titania nanotube arrays (TNAs) were fabricated by electrochemical anodization at high voltage in very short time. A novel approach was developed to decorate CdS nanoclusters on tube top and quantum dots on tube side walls by using the method of ultrasonically-assisted successive ionic layer adsorption and reaction (U-SILAR). This U-SILAR not only helps remove the defective structure from the top surface of TNAs but also improve the adhesion of CdS on TNAs. Moreover, the photoelectric current of U-SILAR samples shows significant enhancement as compared with the samples fabricated by traditional SILAR. As a cover layer, ZnO film was found to further improve the photoelectric performance of the sandwich nanocomposite film. The mechanism was investigated. Finally, the properties of interface in nanocomposite system were studied by electrochemical impedance spectroscopy. The processes developed in this study can be adopted to fabricate sandwich nanostructures of other materials system with desired properties for device applications.