Synthesis, photostability and photocatalytic properties of water-suspended cadmium selenide and cadmium selenide/cadmium sulfide quantum dots

Photocatalysis offers exciting opportunities in the development of a renewable energy source and environmentally-friendly chemical processes. Previous studies focused on titanium dioxide and non-oxide semiconductor nanoparticles (quantum dots), such as CdS, ZnS, MoS2 for photocatalytic breakdown of organic molecules. Catalytic performance has been limited by materials issues, e.g. low quantum yields and photocorrosion. CdSe quantum dots are a model semiconductor nanoparticle material with great potential in luminescence application, but they have not been studied for photocatalysis. In this study, the synthesis of the water-suspended CdSe and CdSe/CdS quantum dots was thoroughly studied. The CdSe and CdSe/CdS core/shell quantum dots were found to photocatalyze the degradation of 4-nitrophenol in water upon the UV-vis irradiation. Quantum efficiencies were low. The pH of the suspending fluid was found to be important in controlling colloidal stability, chemical stability, and reaction during irradiation