pH dependent luminescence switching of tin disulfide quantum dots

Designing a molecule with pH, temperature and ion concentration sensitive luminescence properties is always fascinating. Tin disulfide (SnS2), a member of layered metal dichalcogenides (LMDs) family, is explored much for their commendable applications, however, its fluorescence property is still less explored. Present study reports a facile and eco-friendly bottom up synthesis route for fin disulfide quantum dots (SnS2-QDs). Transmission electron microscopic (TEM), and Atomic force microscopic (AFM) analysis revealed an average particle size of similar to 3.6 nm. Our reported synthesis method provide the in-situ functionalization of quantum dots (QDs) making it highly sensitive to its environment. SnS2-QDs are found to be pH sensitive and hence a detailed pH dependent luminescence study has been performed. Interestingly it was found that SnS2-QDs possess similar to 16 fold enhanced luminescence intensity in acidic condition (pH similar to 1, QY = 5.32%) rather its basic condition (pH similar to 12, QY = 1.17%). To explain this pH dependent behavior of SnS2-QDs, a mechanism has been proposed where this luminescence switching is mainly supposed due to protonation and deprotonation between -NH2 and -COOH groups. We believe present study may provide an insight for the development of pH sensor using SnS2-QDs for practical applications.