An enhanced CdS/TiO2 photocatalyst with high stability and activity: Effect of mesoporous substrate and bifunctional linking molecule

Abstract

To accomplish the more effective coupling of cadmium sulfide quantum dots (CdS QDs), the mesoporous TiO₂ substrate and bifunctional linker, mercaptopropionic acid (MPA), were used to disperse and stabilize the CdS QDs. Due to the porous nano-architecture on the TiO₂ substrate with large surface area and high crystallinity, the efficiency of degradation of organic compounds in aqueous solution under visible light irradiation is greatly enhanced, compared to CdS loaded anatase TiO₂ without porous structure and common commercial P25. Furthermore, the bifunctional linking molecule, MPA, could effectively disperse and stabilize CdS nanoparticles. CdS/TiO₂ with the linking molecule CdS-MPA-TiO₂(m) exhibits much more stability and activity than CdS-TiO₂(m) which is prepared by direct deposition. After 3 cycling tests of degradation of MB (methylene blue), the loss ratio of CdS on CdS-TiO₂(m) is 70.6%, much larger than that of 17.8% on CdS-MPA-TiO₂(m). This work may give ideas for the synthesis of other stable and active supported catalysts in many fields.