Sonication-assisted Ion-Intercalation Exfoliation of MoS2 Quantum Dots

Synthesis of MoS2 quantum dots (QDs) by a sonication-assisted ion-intercalation process where sodium hydroxide (NaOH) is used as sodium (Na+) and hydroxyl (OH−) ions source for the intercalation purpose is reported. The exfoliation method results in well-exfoliated mono- to few-layered QDs as illustrated by the atomic force microscopy (AFM) measurements, showing a thickness of < 1.6 nm, and confirmed by X-ray diffraction (XRD) studies where the characteristic peak at 2θ = 14.4° of bulk 2H-MoS2 disappears. The Raman spectroscopy measurements of the QDs show a frequency difference of 19.8 cm−1 between the E and A1g vibration modes and are in good agreement with the AFM and XRD results. The reported exfoliation technique resulted in an improvement of 7