pH dependent luminescence switching of tin disulfide quantum dots

Abstract

Abstract 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 tin disulfide quantum dots (SnS2-QDs). Transmission electron microscopic (TEM), and Atomic force microscopic (AFM) analysis revealed an average particle size of ∼3.6\u202fnm. 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 ∼16 fold enhanced luminescence intensity in acidic condition (pH\u202f∼\u202f1, QY\u202f=\u202f5.32%) rather its basic condition (pH\u202f∼\u202f12, QY\u202f=\u202f1.17%). 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.