One-pot synthesis of photoluminescent carbon nanodots by carbonization of cyclodextrin and their application in Ag+ detection

Abstract

A simple one-pot approach is developed for the preparation of carbon nanodots (C-dots) by low temperature hydrothermal carbonization of cyclodextrin in a hydrochloric acid aqueous solution. The cyclodextrin-based C-dots have a narrow size distribution and show a high fluorescence quantum yield. The C-dots possess excitation-independent downconversion and upconversion photoluminescent (PL) properties, and have a strong green luminescent emission with a maximal peak at 510 nm when they are excited at 420 nm. Besides, the PL properties of the C-dots have a non-obvious change in a wide range of pH values of 5–11. The fluorescence lifetime of the C-dots is about 2.5 ns. Moreover, the obtained C-dots are able to reduce Ag⁺ ions to elemental silver (Ag⁰) on their surface under sunlight, leading the PL intensity to be linearly changed with the Ag⁺ concentration, which can serve as an effective fluorescent probe for the detection of Ag⁺ in an aqueous solution.