The synthesis of water-dispersible zinc doped AgInS₂ quantum dots and their application in Cu²⁺ detection

In this study, a facile and effective method based on mini-emulsion/solvent evaporation technique was designed to synthesize water-soluble zinc-doped AgInS₂ (AIZS) quantum dots stabilized by dodecyltrimethylammonium bromide (DTAB). Subsequently, the as-synthesized nanocomposites were successfully used as sensitive and selective fluorescence nanoprobe for copper(II) detection. Fluorescence of the cadmium-free AIZS-DTAB QDs could be significantly quenched upon the addition of copper(II), and the quenching degree (I₀/I) was proportionally linear with copper(II) concentration ranging from 0.05 to 10 μM with a low detection limitation of 15 nM. The quenching mechanism was found to be due to electron transfer mechanism as confirmed by X-ray photoelectron spectroscopy (XPS) measurements. This nano-probe shows good selectivity toward copper(II) in aqueous solution with a quick response of 1 min, offering great potential to determine the copper(II) concentration in drinking water and natural water resources.