Bifunctional TiCl4 treatment in CdSe quantum dots sensitized TiO2 microrods for photoelectrochemical water splitting

Rutile TiO2 microrods (TOMRs) were synthesized using a facile hydrothermal method and subsequently surface-treated with TiCl4 solution at different concentrations. CdSe quantum dots (QDs) were assembled on the TiO2 films as a sensitizer to improve the light harvesting efficiency in visible light, because the TiO2 absorbs only UV light. As the concentration of TiCl4 solution to 200 mM was increased, the surface coverage of anatase TiO2 nanoparticles and the loading of CdSe QDs also increased. Furthermore, the anatase TiO2 between the rutile TOMR and the CdSe QD facilitates the charge separation, which suppresses the charge recombination. Due to these beneficial effects, the photoelectrochemical performance was significantly enhanced with the increased TiCl4 concentration.