Hydrothermal synthesis of nitrogen-doped carbon quantum dots from microcrystalline cellulose for the detection of Fe3+ ions in an acidic environment

Nitrogen-doped carbon quantum dots (NCQDs) have been synthesized by the hydrothermal method with microcrystalline cellulose as carbon source and ethylenediamine as nitrogen dopant. The synthesized NCQDs were characterized by FT-IR, TEM, XPS, UV-vis, XRD and fluorescence emission spectroscopy. It was found that nitrogen species were efficiently doped into the carbon framework of the CQDs. The obtained NCQDs were spherical particles with an average diameter of 3.2 nm. Furthermore, the NCQDs showed better fluorescence emission properties and higher quantum yield in acidic solution than CQDs. When used as a fluorescent probe for Fe3+ detection via fluorescent quenching, high selectivity and sensitivity were achieved, and the limit of detection of Fe3+ was as low as 0.21 nM in the acidic environment. The quenching process of NCQDs by Fe3+ was proved to be a dynamic quenching by using fluorescence decay times analysis.