Interface\nNucleophilic Substitution Reaction-Driven\nPrecise Growth of Ag<sub>2</sub>Te Quantum Dots

Surface ligands of quantum dots (QDs) play pivotal roles\nin determining\ntheir optical properties and stability during the growth process.\nThe stability and continuous growth of nanocrystals are crucial to\nprecisely tuning their properties. However, the dilemma surrounding\nthe stability of nanocrystals and their continuous growth remains\nunsolved, posing a formidable challenge. Herein, we have proposed\na strategy for precise tuning of Ag<sub>2</sub>Te QD growth driven\nby nucleophilic substitution reaction (SN2) between surface-bound\nthiol ligands and halogenated hydrocarbons (RX, X = Cl, Br, I), prompted\nby the generation of silver halide precipitate. As a result, Ag<sub>2</sub>Te QDs with emission wavelengths precisely and continuously\ntunable in the range of 1176–2023 nm have been successfully\nsynthesized in one pot. As the reaction advances, the quantity of\nthe more strongly coordinating RS<sup>–</sup> gradually diminishes,\nwhile that of the weaker coordinating dioctyl sulfide gradually increases.\nThis dynamic process enables the growth of the QDs. The rate of the\nSN2 reaction can be adjusted by varying the species and concentration\nof RX, as well as the amount of Ag species, significantly influencing\nthe growth rate of the QDs, a crucial factor for resolving the dilemma\nbetween the stability and tunability of the QDs. Additionally, this\nproposed strategy holds the potential to modulate the properties of\nvarious nanoparticles through chemical reactions at the interfaces.