Fabrication of MoS2 nanoparticle dispersions using ultrasonic methods: synthesis techniques and optical characterization

This study outlines the process of preparing a dispersion of MoS2 nanoparticle from micron sized MoS2 powder using ultrasonic methods. The optical characteristics of this dispersion were investigated using optical measurement techniques. N-methyl-2-pyrrolidone is chosen as the dispersion solvent due to its surface energy closely matching that of MoS2. Consequently, the dispersion that ensued exhibits commendable stability. The MoS2 dispersion underwent analysis through EDX, scanning electron microscopy, and transmission electron microscopy techniques to examine the correlation between the size of the MoS2 nanoparticles and the morphology of the dispersion. The dispersion color intensifies with the increase in the wavelength. A He-Cd laser with a wavelength of 325 nm was used to stimulate and generate the matching light source for the generated samples to leverage the photoluminescent attribute of MoS2 nanoparticles within the range of less than 100 nm. In the Raman measurement graph, distinct peaks can be observed in the generated nanoparticles, providing evidence of their material qualities. The surface morphology of the optical microscopic image was assessed using ultra-spectral imaging technology, allowing for the measurement and acquisition of the associated wavelength spectrum. The particle size in the dispersion was measured using the dynamic light scattering technique. These tests demonstrate that the process can be fine-tuned by adjusting parameters, such as ultrasonic oscillation time and centrifugal time. This process can also yield MoS2 nanoparticle dispersions in various sizes, each exhibiting distinct photoluminescence characteristics corresponding to the excited light wavelength.