Abstract

Molybdenum disulphide (MoS2) is commonly exfoliated and dispersed in organic solvents for a number of technological applications. However, little is known about the effects of electrolytes on the colloidal stability of these dispersions. In this study, stable dispersions of MoS2 nanosheets were prepared in 1,2-dichlorobenzene (DCB) by ultrasonication. The dispersion was characterized using UV-Vis absorption spectroscopy, scanning electron microscopy, atomic force microscopy and Raman spectroscopy. The aggregation kinetics of the MoS2 dispersion was investigated at different concentrations of an organic electrolyte, bis(triphenylphosphoranylidene) ammonium tetrakis (4-chlorophenyl) borate, using sedimentation method based on the change in UV-Vis absorption of the MoS2 dispersion with centrifugation time after the addition of the electrolyte. Increasing electrolyte concentration in the dispersion induced MoS2 aggregation by the screening of the electrical double layer repulsion (EDL) barrier around the MoS2 nanosheets. The critical coagulation concentration (CCC) was estimated as 21.8 µM. The result of this study demonstrates that electrostatic repulsion contributes substantially to the stability of the MoS2 organic dispersion.

Key words: MoS2, Dispersion stability, Aggregation Kinetics, Critical Coagulation Concentration, Organic electrolyte