Ionic liquid as a precursor to synthesize nitrogen- and sulfur-co-doped carbon dots for detection of copper(II) ions

A facile approach was reported for the synthesis of nitrogen- and sulfur-co-doped carbon dots(N/S-CDs) by the sulfuric acid carbonization of 1-butyl-3-methylimidazolium 2-amino-3-mercaptopropionic acid( L -cysteine) salt([C 4 mim][Cys]) ionic liquid. The as-prepared N/S-CDs exhibited a good solubility, excitation-dependent emission behavior, and high resistance to photobleaching. Furthermore, the N/S-CDs were employed as a fluorescent probe for detecting Cu 2+ in real water samples with satisfactory recovery.