A fluorescent CQDs for the Cu²⁺ detection in water

Abstract In order to obtain high efficiency and high precision fluorescent detection agent of trace metal ions in solution, the CQDs were optimized with citric acid, which acted as a carbon source, as well as urea, which acted as a nitrogen source. It was a carbon nanoparticle with a particle size of around 3.16 nm, featuring numerous functional groups attached to the surface. These attributes not only facilitated its dispersion within water but also conferred increased stability, thereby resulting in a more consistent fluorescence intensity. It was a fluorescent sensor that could successfully detect copper ions (Cu2+) in the range of 3-5 mM. First, we set the excitation wavelength to 380nm. Then, the quenched CQDs fluorescence intensity would be found, which was defined as the dynamic quenching of energy transfer caused by the binding of amine groups and Cu2+. CQDs were actually applied to detect Cu2+ in the concentration range 2-6 mM, with R2=0.9565. Thus, the CQDs had high practical application value for metal ion detection and alcohol sensing.