Thioglycolic acid-capped CuInS2/ZnS quantum dots as fluorescent probe for cobalt ion detection

A novel sensing fluorescent probe based on the fluorescence quenching of the thioglycolic acid-capped CuInS2/ZnS quantum dots (CuInS2/ZnS/TGA QDs) was established for cobalt ions detection. The fluorescence quenching of CuInS2/ZnS/TGA QDs was due to the increasing surface deficiency and the inner-filter effect, which were attributed to the reaction between Co2+ and sulfur bonds on the surface of QDs. The quenching curve could be fitted by a typical Stern–Volmer-type equation, with a linear relationship between the quenching efficiency and the concentration of cobalt ions in the range of 0.3012–90.36 μmol L−1. And the detection limit (S/N=3) for Co2+ was 0.16 μmol L−1. Therefore, the established probe provided a simple, rapid, cheap and sensitive method for Co2+ detection. In a word, this method can be used to detect Co2+ in the environment. -- Highlights: • The CuInS2/ZnS QDs were used for the first time as a fluorescent probe for Co2+ detection. • The dramatic color change could be observed when Co2+ was added into the QDs solution. • The quenching of QDs was due to the increasing surface deficiency and the inner-filter effect. • This rapid, cheap and sensitive method was applied to the detection of Co2+ in simulated water