Visible light photocatalysis via 3D-ordered macroporous TiO2 films sensitized with CdS quantum dots.

CdS quantum dots (QDs)-sensitized TiO2 film with three-dimensionally (3D) ordered macropores was synthesized via a two-step method on ITO glass substrate. 3D-ordered macroporous TiO2 film was firstly fabricated on an ITO glass via layer-by-layer deposition and hydrolysis of tetrabutyl titanate using 3D-ordered latex film as organic template, followed by calcination at 450 degrees C for 2 h to remove the template. Then, the CdS QDs were deposited on the 3D-ordered macroporous TiO2 film by successive ionic layer adsorption and reaction technique. The as-prepared CdS-sensitized TiO2 film was characterized with X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, diffusive reflectance UV-visible absorption spectra, and photoelectrochemical measurements. Its photocatalytic activity was evaluated by the photocatalytic degradation of crystal violet aqueous solution at ambient temperature. It was revealed in our results that the CdS QDs-sensitized 3D-ordered macroporous TiO2 film exhibits enhanced photocatalytic activity for the photodegradation of crystal violet than that of the CdS-free 3D-ordered macroporous TiO2 film and that of CdS QD-sensitized TiO2 film without 3D-ordered macropores under the irradiation of visible light due to the co-existence of 3D-ordered interconnected macropores and the sensitization of CdS QDs.

CdS quantum dots sensitized solar cells based on free-standing and through-hole TiO2 nanotube arrays.

Front-side illuminated solar cells with CdS quantum dots (QDs) incorporated with free-standing through-hole TiO2 nanotube arrays (TNAs) were developed. The solar cells, based on TNAs with different lengths that were sensitized by successive ionic layer adsorption and reaction method (SILAR) with various cycles, have been tested. The morphology and crystalline phase of the TiO2 nanotubes were studied by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The crystallized free-standing through-hole TNAs were easily transferred to the fluorine-doped tin oxide glass to form a photoanode by slightly modifying the anodization procedure. The SILAR technique enables us to control the loading amount and particle size of CdS QDs by altering deposition cycles. The cells with TNAs ca. 20 µm long (obtained by anodization for 4 h) and 5 SILAR cycles show a photovoltaic conversion efficiency as high as 1.187% under simulated sunlight (AM 1.5, 100 mW cm(-2)).