Bright, green fluorescent carbon dots for sensitive and selective detection of ferrous ions

Iron is critical to living organisms; excess or lack of iron could lead to a series of diseases. In this work, fluorescent carbon dots were developed as an efficient probe for sensitive and selective detection of ferrous ions (Fe2+). We reported on simple and one-pot synthesis of uniform, bright, and green fluorescent carbon dots with aqueous stability in a wide pH range. The formation of green fluorescence is attributed to the doping of nitrogen into carbon materials. The as-synthesized carbon dots demonstrated wavelength-independent emission properties. Fluorescence of carbon dots was quenched efficiently, sensitively and selectively by ferrous ions over a series of other common metal ions and anions, with a detection limit of 16 µM, and a wide detection range of 0.033 -1.044 mM. Efficient quenching of carbon dots could be explained by the efficient binding of ferrous ions on carbon dots surface. Aggregation caused quenching was later proposed and verified as the quenching mechanism of carbon dots toward ferrous ions. The developed carbon dots show great promise in the development of efficient sensors and adsorbents for ferrous ions.