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.