Facile aqueous synthesis of ZnInS quantum dots and its application for selective detection of Co2+Ions.

The synthesis of ZnInS (ZIS) quantum dots (QDs) in aqueous medium using thioglycolic acid (TGA) and sodium citrate as dual capping agents has been reported. The as-synthesized ZIS QDs were water soluble, emitting at 512 nm and nearly spherical in shape with average particle size of 8.9 ± 1.4 nm. The as-synthesized ZIS QDs were tested for its fluorescence response against different metal ions and the results revealed that ZIS QDs were selectively quenched by Co2+ions compared to other ions. The fluorescence sensing experiment showed that ZIS QDs has a linear response against the concentration of Co2+ions (0.1-100μM ) with the detection limit of 0.099μM. Based on the transmission electron microscope and absorption spectroscopy analyzes, the fluorescence quenching is attributed to the formation of surface ligand-metal complex (TGA-Co2+ions) which caused aggregation of the QDs. The present method explores the synthesis of zero-dimentional ZIS QDs and its potential in the selective detection of Co2+ions in aqueous solution.