The use of MoS2 nanosheets as oil additives has been proved effective to reduce friction and wear. Furthermore, it has been suggested that the synthesis of MoS2 nanosheets with an ultrathin structure could benefit the friction and wear reduction, as they would penetrate into the contact area easily. In this paper, two-dimensional MoS2 nanosheets were successfully fabricated by a solvothermal method with the aid of oleylamine. Meanwhile, the synthesized MoS2 nanosheets exhibited perfect dispersing stability in paraffin oil, due to the surface modification by oleylamine molecules. The friction and wear properties of the synthesized MoS2 nanosheets as oil additives were investigated using a ball-on-disk tribotester. The results showed that the two-dimensional MoS2 nanosheets exhibited enhanced friction-reducing and antiwear behaviors as compared to the multilayered MoS2 nanosheets. The prominent tribological performance of the two-dimensional MoS2 nanosheets was attributed to the formation of a thick tribofilm inside the wear tracks, which was confirmed by XPS analyses of the rubbing interfaces.
