Sensitive Detection of Sulfide Ion Based on Fluorescent Ionic Liquid-Graphene Quantum Dots Nanocomposite.

Sulfide ions (S) that are widely distributed in biological and industrial fields are extremely toxic and pose great harms to both ecological environment and human health. However, fluorescent sensors toward S ions commonly use S-recovered fluorescence of fluorophore that is first quenched mainly by metal ions. Fluorescent probe which enables direct, selective, and sensitive detection of S ion is highly desirable. Herein, we demonstrate one-step preparation of fluorescent ionic liquid-graphene quantum dots (IL-GQDs) nanocomposite, which can act as a fluorescent probe for direct and sensitive detection of S ion. The IL-GQDs nanocomposite is easily synthesized facile molecular fusion of carbon precursor and surface modification of GQDs by IL under hydrothermal condition. The as-prepared IL-GQDs nanocomposite has uniform and ultrasmall size, high crystallinity, and bright green fluorescence (absolute photoluminescence quantum yield of 18.2%). S ions can strongly and selectively quench the fluorescence of IL-GQDs because of the anion exchange ability of IL. With IL-GQDs nanocomposite being fluorescent probe, direct and sensitive detection of S is realized with a linear detection range of 100nM-10μM and 10μM-0.2mM (limit of detection or LOD of 23nM). Detection of S ions in environmental river water is also achieved.