Morphological effect of MoS2 nanoparticles on catalytic oxidation and vacuum lubrication

The closed layered MoS2 nano-balls and the opened layered MoS2 nano-slices were prepared by decomposing MoS3 in hydrogen atmosphere. The obtained MoS2 nanoparticles were respectively used as catalysts for S-2 oxidation into SO42 and lubricating fillers in polyoxymethylene (POM) plastic. Only basal surface could be found in the closed layered MoS2 nano-balls, which represented very low catalytic efficiency for S-2 oxidation into SO42. However, the opened layered MoS2 nano-slices were of both basal surface and rim-edge surface and showed excellent catalytic properties. Moreover, it was shown that MoS2 nano-balls could improve the self-lubrication of POM plastic in vacuum. However, MoS2 nanoslices led to the obvious degradation of POM, implying it is not a proper additive for POM. The high activity of MoS2 nano-slices for catalyzing S-2 oxidation and degrading POM was ascribed to their small sizes and partly wedge-like shapes, which led to a considerable increase in the rim sites. The weak catalysis and excellent lubrication of MoS2 nano-balls were resulted from its closed structure and chemical inertness. (C) 2009 Elsevier B.V. All rights reserved.