Increasing demands of multi-functional lubricant materials with well distributed nanoparticles has been generated in the field of oil lubrication. In this study, one-dimensional (1-D) acidified multi-walled carbon nanotubes (CNTs) and two-dimensional (2-D) graphene oxide (GO) sheets were dispersed together under an ultra-sonication condition to form CNTs/GO hybrids and the corresponding CNTs/GO hybrids decorated with uniform zero-dimensional (0-D) cerium oxide (CeO₂) nanoparticles were prepared via a facile hydrothermal method. The tribological performance of CeO₂/CNTs/GO ternary nanocomposite was systematically investigated using a MS-T3000 ball-on-disk tester. The results demonstrated that CeO₂/GO/CNTs nanocomposites can effectively reduce the friction of sliding pairs in paraffin oil. Moreover, the oil with 1 wt% of CeO₂/GO/CNTs exhibited the best lubrication properties with the lowest friction coefficient and wear scar diameters (WSD) compared with adding only GO nanosheet, CeO₂, and CeO₂/CNTs hybrid nanocomposite as lubricant additives. It is concluded that due to the synergistic effect of 0D CeO₂, 1D CNTs, and 2D GO during sliding process, a dimensionally mixed CeO₂/GO/CNTs nanocomposite exhibits excellent lubricating properties, providing innovative and effective additives for application in the field of lubrication.

The dispersibility of lubricant additives in water plays great roles in the performance of water-based lubrication. Here we successfully prepared fluorinated carbon nanotubes (F-CNTs) via a facile hydrothermal method. The newly obtained F-CNTs could be further modified by urea to obtain urea modified fluorinated carbon nanotubes (UF-CNTs) with hydrophilic functionalities. Abundant covalently bonded hydrophilic groups on the surface of UF-CNTs endows them with improved self-dispersed characteristic in water, which overcomes the shortcomings of hydrophobicity for both carbon nanotubes (CNTs) and F-CNTs as water-based lubricant additives. Besides, the results from friction and wear tests indicate that the addition of a small amount of UF-CNTs can significantly improve the tribological properties of pure water. Notably, a water-based lubricant with as little as 0.15 wt% UF-CNTs added exhibits excellent friction reduction and very high wear resistance performance in terms of 80.86% and 96.70% decreases in friction coefficient and wear rate, respectively, compared with pure water. The tribological investigation in this study strongly suggests that the as-prepared UF-CNTs have great potential for application as effective water-based additives for lubrication.

Molecular dynamics simulations were used to investigate the influence of the confined mass transfer effect on the separation of Mg²⁺ and Li⁺ from graphene oxide membranes, both in terms of layer spacing and degree of oxidation.