Stabilizing NIR emission of Ag₂S quantum dots in water using SnS₂ Shell

In this study Ag₂[email protected]₂ core-shells were synthesized successfully for the first time. Pulsing microwave irradiation was quite an effective technique for the controlled growth of core-shells using a one pot technique. Different parameters were optimized in the synthesis of core-shells and they were verified structurally using X-ray diffraction (XRD), Energy dispersive x-ray spectroscopy (EDX), Transmission electron microscopy (TEM) and Fourier Transform Infrared Spectroscopy (FTIR). Ultraviolet-Visible spectroscopy (UV–Vis) revealed a strong absorption at 805 nm. Photoluminescence spectroscopy (PL) showed that the samples had a considerable emission around 870 nm and it was stable for at least 30 days in water. EDX analysis confirmed the presence of Sn, Ag and S atoms in the samples and their atomic ratio was quite close to their nominal chemical values. XRD analysis showed the formation of Ag₂S monoclinic and SnS₂ hexagonal phases. TEM images showed clearly formation of core-shells with sizes below 10 nm. FTIR spectroscopy revealed that thioglycolic acid (TGA) is an effective and stable capping agent for the synthesis of Ag₂[email protected]₂ core-shells using this pulsing technique.