Structural and Optical Properties of Core–Shell TiO2/CdS Prepared by Chemical Bath Deposition

Abstract

Titanium dioxide (TiO2) nanorod arrays (NRAs) sensitized with cadmium sulfide (CdS) nanoparticles (NPs) were deposited by chemical bath deposition (CBD). TiO2 NRAs were also obtained by using the same method on glass substrates coated with fluorine-doped tin oxide (FTO). The structure of the FTO/TiO2/CdS core–shell was characterized by x-ray diffraction (XRD), atomic force microscopy, scanning electron microscopy, ultraviolet–visible (UV–Vis) absorption spectroscopy, photoluminescence, and photoelectrocatalysis of FTO/TiO2 and FTO/TiO2/CdS. The FTO/TiO2 conformed to anatase and rutile phase structures for different pH values and also with annealing. XRD patterns of the FTO/TiO2/CdS sample exhibited two peaks corresponding to hexagonal (100) and (101) for CdS. Scanning electron micrographs showed nanorod structures for the TiO2 thin films deposited at a pH value equal 0.7. Optical results showed the CdS deposited on nanorod TiO2 exhibited increased absorption ability in the visible light, indicating an increased photocatalytic activity for TiO2/CdS core–shell nanorods in the visible light. When illuminated with a UV–Vis light source, the TiO2/CdS core–shell films displayed high responses. A composite exists between the TiO2 nanostructure and CdS NPs because the film absorbs the incident light located in both the visible and UV–Vis regions. A higher response to UV–Vis light was attained with the use of TiO2 NRAs/CdS NPs films prepared by CBD. This approach offers a technique for fabricating photoelectrodes.