Facile, rapid and efficient doping of amorphous TiO2 by pre-synthesized colloidal CdS quantum dots

Abstract Various methods have been developed to reduce the band gap of TiO 2 via combining TiO 2 with quantum dots (QDs). However, the attainment of high activity and stability of hybrid QDs/TiO 2 is still a significant challenge since the poor interface contact between QDs and TiO 2 . This drawback could be tackled to some extent through optimisation of the preparation technology. The present study suggests a simple hydrolysis route to in situ TiO 2 doping by pre-synthesized CdS QDs, which play a role of crystal seeds, pre-planted in liquid titanium alkoxide, for the TiO 2 crystallization process. The comprehensive investigation of the CdS/TiO 2 composite is carried out by X-ray diffraction, UV–Visible spectroscopy, scanning electron microscopy, photocatalytic activity measurements in the photo oxidation of cyclic aromatic organic compounds. The stability of model TiO 2 -shell structures on CdS seeds is assessed by means of molecular dynamics simulations. Both experimental and theoretical results confirm the mutual impact of CdS QDs and TiO 2 on their crystallinity. The presence of CdS QDs in the solution provokes the formation of amorphous TiO 2 clusters, while the high TiO 2 content leads to amorphization of CdS QDs. The CdS/TiO 2 composite particles consisting of CdS amorphous core and TiO 2 amorphous shell demonstrate the highest photocatalytic activity.