▎ 摘　　要

Although graphene oxide (GO) is deemed as an admirable lubricant additive to enhance the tribological properties of water, there remain great challenges in improving its dispersion stability and re-dispersity in water, and understanding the effects of dispersity and exfoliation degree on lubricity of GO. Herein, the functionalized GO (GO-EmimN(CN)(2)) with extraordinary dispersity, re-dispersity and high exfoliation degree is successfully prepared using 1-ethyl-3-methyl imidazolium dicyanamide as intercalator of multilayer graphene oxide (MGO). GOEmimN(CN)(2) as water-based lubricant additive dramatically decreases the wear rate and wear width of GCr15 steel by 74% and 40% compared to pure water, 53% and 45% to MGO respectively. Finally, lubricating mechanisms of GO-EmimN(CN)(2) are determined and proposed via abundant surface analysis techniques.