Synthesis of highly luminescent POSS-coated CdTe quantum dots and their application in trace Cu2+ detection

Abstract

CdTe quantum dots coated by octamercaptopropyl polyhedral oligomeric silsesquioxane (OM-POSS) were applied to detect trace Cu²⁺. This detection method is based on selectively quenching the fluorescence originating from the CdTe QDs in the presence of Cu²⁺. The research showed a low interference response of the POSS-coated CdTe QDs towards other metal ions. The POSS-coated CdTe QDs obtained a higher sensitivity than NAC-coated CdTe QDs. The quenching mechanism is discussed on the basis of the competitive binding of the thiol groups of the OM-POSS between the CdTe QDs and the metal ions. The Stern–Volmer plots at different temperatures show that the fluorescence of the POSS-coated CdTe QDs was quenched by Cu²⁺ through a static quenching mechanism. The response of the QDs fluorescence intensity is linearly proportional to the Cu²⁺ concentration ranging from 1 × 10⁻⁸ to 1 × 10⁻⁶ mol L⁻¹ with a detection limit of 2.3 × 10⁻⁹ mol L⁻¹. Furthermore, the method has been successfully applied to the detection of Cu²⁺ in water samples.