A novel and green method to synthesize CdSe quantum dots-modified TiO2 and its enhanced visible light photocatalytic activity

In this paper, a facile and green method was employed to synthesize CdSe quantum dots (QDs)-modified TiO 2 . It exhibited much higher photocatalytic activities than both TiO 2 and bulk CdSe-modified TiO 2 on degrading malachite green (MG) aqueous solution under visible light irradiation. The vital role that quantum size effect of CdSe QDs plays in enhancing photocatalytic properties of CdSe QDs-modified TiO 2 is discussed in detail for the first time. Due to the more negative conduction band potentials of CdSe QDs than that of bulk CdSe, the electron transfer rate from CdSe QDs to TiO 2 is much faster than that from bulk CdSe to TiO 2 , which would be beneficial for an efficient charge carrier's separation. As a result, more quantities of active species (O 2 • − , H 2 O 2 , •OH) are generated during the photocataltytic reaction in CdSe QDs-modified TiO 2 system. This work could not only provide a facile and green strategy to fabricate semiconductor QDs-modified TiO 2 photocatalyst but also contribute to a deeper understanding of the specific role of semiconductor QDs during the photocatalytic reaction process.