Solvent effects on the formation and absorption spectra of nanodisperse molybdenum disulfide

The optical absorption spectra of molybdenum disulfide prepared by monolayer dispersion of a crys- talline precursor in a liquid medium were studied. On the whole, the three-dimensional structure of the crystalline analogue was reconstructed in disperse MoS 2 dried to a powder state. A substantial fraction of the material trans- formed into a nanosized state during dispersion and was stabilized in the form of nanoparticles in various sol- vents. The stabilizing action of the solvents studied decreased in the series acetonitrile, ethanol > chloroform > water. The data on the optical absorption of MoS 2 suspensions in various solvents were evidence of a broad par- ticle-size distribution. Along with nanoscale particles, the samples contained larger particles responsible for long-wave absorption (>600 nm). The size of nanoparticles was estimated using an empirical correlation between the position of maximum A (the long-wave maximum of the first allowed absorption band) in the absorption spectrum and the size of particles ( 2 R ). This correlation was obtained using the literature data on monodisperse particles and mixtures of particles. The number of particles showed a tendency to increase as the concentration of disperse MoS 2 in acetonitrile decreased.