Preparation of InP quantum dots-TiO2 nanoparticle composites with enhanced visible light induced photocatalytic activity†
Abstract
Environmentally friendly InP-based quantum dots (QDs) are expected to be ideal visible-light-harvesting materials because of their unique photophysical properties. Herein, we report on the results of using a combination of InP/ZnSe (core/shell) QDs and TiO2 nanoparticles (NPs) as visible-light-responsive photocatalysts. Strong negatively charged sulfonate functional ligands were introduced onto the InP/ZnSe QD surface, and the negatively charged InP/ZnSe QDs were electrostatically conjugated to the oppositely charged TiO2 NP surface. Scanning electron microscopy images confirmed that the entire TiO2 surface was densely coated with QDs, and the QD–TiO2 interaction was maintained in acidic and neutral media. The band-edge photoluminescence (PL) intensity of the QDs was reduced after they were linked to the TiO2, indicating that the photoexcited electrons in the InP/ZnSe QDs were readily transferred to the TiO2. The spatially separated photoinduced charge carriers with suppressed charge recombination of the InP/ZnSe QD–TiO2 conjugates enhanced the photocatalytic degradation efficiency of rhodamine B dye. Both the charge generation over a broad solar spectral range and the electron–hole separation capabilities of the InP/ZnSe QD–TiO2 can provide many new possibilities for solar energy harvesting systems.