Crown daisy leaf waste-derived carbon dots: A simple and green fluorescent probe for copper ion

In this paper, N-doped carbon quantum dots (N-CDs) were fabricated using crown daisy leaves, a kitchen waste, as carbon source. The synthesized N-CDs possessed abundant surface functional groups, such as hydroxyl, carboxyl, and amino groups, and had good dispersibility in water. Because of the special fluorescence quenching property toward Cu2+, the synthesized N-CDs can be exploited as an effective label-free fluorescent probe for Cu2+ determination. The possible fluorescence sensing mechanism considered the selective coordination interaction between Cu2+ ion and the hydroxyl, carboxyl, and amino groups of the N-CDs. The control experiments also showed that the N-doped aromatic C-N heterocycle structure played a crucial role in selective sensing of Cu2+. The decrease in fluorescence efficiencies was linearly related with the Cu2+ concentrations in the range of 10.0nM to 120.0nM, with a response limit of 1.0nM. The prepared probe was also applied for Cu2+ determination in real river water.