▎ 摘　　要

Study on structure-activity relationship between size and tribological properties of graphene oxide nanosheets(GO) in oil for the first time was presented. GO nanosheets with different size dimensions were prepared under different oxidation temperatures by using the improved Hummers method. The phase structure, size distribution and oxygen content of as-prepared GO nanosheets were determined by characterization techniques. The size dimension was tunable by controlling the oxidation temperature of the improved Hummers method. It was importantly revealed that the C/O ratio descended with the diminishing size of GO. The tribological properties of the resulting GO-based oils were intensively studied. Upon containing 0.04 wt% of GO content in oil, the GO-based oil exhibited the excellent anti-friction and antiwear performance. More importantly, GO nanosheets with the smaller size and lower C/O ratio could significantly improve the tribological properties of oil. (C) 2017 Elsevier B.V. All rights reserved.