▎ 摘　　要

Reduced graphene oxide nanosheet decorated with uniform ceria (CeO2) nanoparticles was prepared via a simple hydrothermal method. The anchored CeO2 nanoparticles with diameters of 3.5-4.5 nm were well distributed on reduced graphene oxide (rGO) nanosheets. The as-prepared CeO2/rGO nanocomposites can be highly dispersed into the paraffin oil to form a stable monodisperse solution at the broad temperature range from -7 degrees C to 160 degrees C. The tribological performance of CeO2/rGO nanocomposites as oil lubricant additives was systematically investigated using a MS-T3000 ball-on-disk tester. The results indicated that paraffin oil with 5 wt% CeO2/rGO exhibited the best lubrication performance in terms of the lowest friction coefficient and wear rate compared to only GO or CeO2 nanoparticles as lubricant additives. Notably, the base oil filled with CeO2/rGO revealed the excellent tribological properties as friction coefficient and wear rate separately decreased by 15.85% and 76.03%, in comparison with the base paraffin oil. Moreover, optical microscope images of the wear surface of the steel disc as well showed that CeO2/rGO nanocomposites exhibited higher anti-wear capability than GO nanosheet and CeO2 nanoparticles. The unique tribological properties of CeO2/rGO suggested the synergistic friction reduction and anti-wear mechanism of rGO nanosheet and CeO2 nanoparticles.