Vertical Growth of Two-Dimensional TiO2 Nanosheets Array Films and Enhanced Photoelectrochemical Properties Sensitized by CdS Quantum Dots

In this paper, we report CdS quantum dots (QDs) sensitized vertical growth two-dimensional titanium dioxide (TiO2) nanosheets array films with oriented {001} facets for the first time. The TiO2 nanosheets array films of thickness about 1.2 μm exposed 85% high-energy {001} facets were perpendicularly grown on transparent conductive fluorine-doped tin oxide (FTO) glass substrates by a simple one-pot hydrothermal method. The CdS QDs sensitized TiO2 photoelectrode was carried out by successive ionic layer adsorption and reaction (SILAR). CdS QDs with a diameter less than 10 nm were uniformly anchored on the surface of the single-crystalline TiO2 nanosheets with active {001} facets. Under AM 1.5 G illumination, the photoelectrode of CdS sensitized TiO2 nanosheets array is found with a photocurrent intensity of 3.24 mA/cm2 at a potential of 0 V versus Ag/AgCl, which is much higher than that of the bare TiO2 nanosheets array with 0.48 mA/cm2. The excellent photoelectrochemical properties of the novel photoanodes suggest that the TiO2 nanosheets array films sensitized by CdS QDs have potential applications in solar cells.