Effect of dispersing graphene oxide with different specifications in water on lubrication performance

Graphene oxide (GO) and reduced graphene oxide (rGO) are known to exhibit low friction when dispersed in water or oil, although the underlying mechanism is not yet fully understood. In this study, five GO and rGO powders were used for friction tests in water dispersion. The structure of graphene (Raman spectrometry), the bonding state of carbon (XPS analysis), and the secondary particle size (dynamic light scattering) were measured to clarify the effects of these factors on the dispersibility of GO and rGO and on the friction coefficient. The results revealed that the smaller the secondary particle size, the higher the dispersibility, and the higher the ratio of -C-O- and C-OOH coordinated to GO and rGO, the lower the friction coefficient.