▎ 摘　　要

We have successfully developed Li+/Na+ co intercalated exfoliation for graphene nanosheets by a hydro thermal method without the participation of any organic solvents. The effect of the Li+/Na+ ratio on the exfoliation of graphite was intensively studied. The chemical structure of the as-prepared graphene nanosheets was confirmed by the characterizations. Moreover the results verified that the, thickness of the as-prepared graphene nanosheets was 2.65-2.78 nm (about 7-8 layers). The potential application of the as-prepared graphene nanosheets in antifriction and antiwear behaviors was investigated in castor oil. The results demonstrated that the antifriction and antiwear performance of the castor oil with 0.04 wt % as-prepared graphene nanosheets was significantly enhanced, up to 36.84% and 48.57%, respectively. The antifriction mechanism was probed by detecting the morphologies and Raman spectra of worn surfaces.