Superhigh-exfoliation graphene with a unique two-dimensional (2D) microstructure for lubrication application

Graphene being a two-dimensional (2D) nanomaterial, is highly regarded in scientific researches and industrial applications for reducing friction energy consumption and improving anti-wear durability. Excellent friction reduction and wear resistance properties can be effectively achieved by microstructural design of graphene. In this study, superhigh-exfoliation reduced graphene oxide (SRGO), synthesized in the presence of graphene oxide (GO), was thermally reduced via the activation of KOH. The SRGO nanosheets show a unique 2D microstructure with little restack and agglomeration. Particularly, SRGO has very large values of specific surface area (1665 m²/g) and of interlayer spacing (4.25 Å). The nanosheets with superhigh degree of exfoliation are studied as lubricant additives for the first time. They show excellent tribological properties, and the coefficient of friction (COF) of base oil can be reduced by 70% and the wear volume by >60%, which are mainly attributed to the unique microstructure, good self-dispersed stability and sliding-oriented transformation of SRGO. The results provide an efficient way to design the microstructure of graphene as a promising candidate for reducing consumption and saving energy.