Highly-enhanced Performance of TiO2 Nanotubes Attached with CdS quantum Dots

In order to utilize the visible light of TiO2 effectively, the heterostructured TiO2 nanotube/CdS nanocomposite was synthesized by a hydrothermal approach. Characterization of the prepared products were performed with scanning electron microscopy, transmission electron microscopy, X-ray diffraction and ultraviolet-visible spectroscopy. The results indicated that the heterostructured TiO2 nanotube/CdS nanocomposite exhibited a significant red shift while the CdS quantum dots were attached on the surface of the TiO2 nanotubes. Based on a quartz crystal microbalance array, TiO2 nanotubes and heterostructured TiO2 nanotube/CdS nanocomposite were used to fabricate a chemical prototype device to study the surface and interface properties of the heterostructured nanocomposite. The adsorption properties of the chemical prototype device to some typical organic volatiles were examined under the same micro-environment. The results showed that the attachment of CdS on the TiO2 nanotubes had enhanced the adsorption properties to those organic volatiles greatly. After the heterostructured TiO2 nanotube/CdS nanocomposite was casted on the surface of Au interdigital electrodes on flexible polyethylene terephthalate substrates, the photoresponse of the nanocomposite was examined with a low-power visible light source to explore the modification mechanism in detail. It was found that the CdS modification enhanced the photo-current of the TiO2 nanotubes to weak visible light. Not only showing enhanced visible light response, but also possessing excellent adsorption properties to organic volatiles, the heterostructured TiO2 nanotube/CdS nanocomposite, has good potential applications in photocatalysts, self-cleaning coatings, photo detectors, chemical and bio-sensors.