Carbon Nitride Quantum Dots: A Novel Fluorescent Probe for Non-Enzymatic Hydrogen Peroxide and Mercury Detection

The mercury species in the ocean (MeHg, Hg 2+ ) will be enriched in marine organisms and threaten human health through the food chain. While the excessive H 2 O 2 in the metabolic process will produce hydroxyl radicals and accelerate the aging of human cells, causing a series of diseases. Hence, the cost-effective and rapid detection of mercury and H 2 O 2 is of urgent requirement and significance. Here, we synthesized emerging graphitic carbon nitride quantum dots (g-CNQDs) with high fluorescence quantum yield (FLQY) of 42.69% via a bottom-up strategy by a facile one-step hydrothermal method. The g-CNQDs can detect the H 2 O 2 and Hg 2+ through the fluorescence quenching effect between g-CNQDs and detected substances. With the presence of KI, g-CNQDs show concentration-dependent fluorescence toward H 2 O 2 , with a wide detection range of 1–1000 µmolL −1 and a low detection limit of 0.23 µmolL −1 . The g-CNQDs also show sensitivity toward Hg 2+ with a detection range of 0–0.1 µmolL −1 and a detection limit of 0.038 µmolL −1 . This dual-function detection of g-CNQDs has better practical application capability compared to other quantum dot detection. This study may provide a new strategy for g-CNQDs preparation and construct a fluorescence probe that can be used in various systems involving H 2 O 2 and Hg 2+ , providing better support for future bifunctional or multifunction studies.