MICROEMULSION-MEDIATED SYNTHESIS OF NANOSIZE MOLYBDENUM SULFIDE PARTICLES

A microemulsion-based method for the synthesis of molybdenum sulfide nanoparticles is reported. Molybdenum sulfide particles in the size range 10-80 nm have been precipitated in water-in-oil microemulsions (water-containing inverse micelles) formulated with polyoxyethylene (5) nonylphenyl ether (NP-5). The particles were synthesized in the NP-5/cyclohexane/water microemulsion system by acidifying ammonium tetrathiomolybdate solubilized in the water cores of the inverse micelles. Particle characterization was accomplished by chemical analysis, transmission electron microscopy, and ultraviolet/visible spectroscopy. The small size and the cage-like nature of the microemulsion water cores limit particle growth and aggregation. The particle size was found to be a function of the water-to-surfactant molar ratio and the average number of ammonium tetrathiomolybdate ions solubilized per water core. These trends are rationalized in terms of classical nucleation theory and aggregative growth concepts. © 1994 by Academic Press, Inc.