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.