Ion-Intercalation Assisted Solvothermal Synthesis and Optical Characterization of MoS₂ Quantum Dots

Many of the previously reported preparation methods for MoS₂ quantum dots (QDs) are limited by production rate, time consumption, tedious processes or the final quality of the as-prepared QDs. Therefore, a simple and productive method for large-scale production of high-quality MoS₂ QDs is still a challenge. We report a facile, low cost and environmentally friendly ion-intercalation assisted solvothermal route for the preparation of MoS₂ QDs. In the reported method, NaOH is used as the Na⁺ ion source to intercalate and exfoliate the commercial MoS₂ powder into nanosheets and then QDs. The reaction is carried out at a certain temperature in a Teflon-lined autoclave reactor. The UV-Vis absorption spectra of the as synthesized QDs show a peak in the near UV region (λ < 300 nm) instead of the characteristic peaks for the nanosheets. Characterization by X-ray diffraction, atomic force microscopy and photoluminescence spectroscopy also confirmed that the as-synthesized QDs had a uniform size distribution in the range of a few nanometers with mostly a monolayer structure and showed good photoluminescence (PL) properties. The proposed method has much potential for further enhancing the yield of MoS₂ QDs by taking advantage of the nature of solution-based processes.