# Fabrication of Novel CeO2/GO/CNTs Ternary Nanocomposites with Enhanced Tribological Performance
## 1 Introduction  
In the continuous development and research of tribology and nanomaterials, except for the improvement of traditional lubricant additives, many researchers focus on introducing nanomaterials into tribology for exploration [1; 2; 3; 4; 5; 6; 7]. Nanomaterials exhibit better anti-friction and wear resistance performance under more severe conditions, which makes them well-studied and applied in terms of friction [8; 9]. Nanomaterials generally have a large specific surface area and surface tension, with the size between 1 and 100 nm. After the surface is modified, it can be uniformly and stably dispersed in some organic solvents [10; 11; 12; 13]. The uniform dispersion of nanomaterials in the base oilcan effectively improve its friction and wear resistance and possess excellent properties that other traditional lubricating oils do not have. Cerium (Ce), a zero-dimensional (0D) nanoparticle, is a kind of rare earth element. Compared with metal nanoparticles, Ce is difficult to oxidize and exhibits excellent tribological properties in marine, aerospace, and other environments. Ce and its compounds as filler can effectively improve the tribological properties of the materials. [PERSON] et al. [14] used CeO\({}_{2}\) and Cu nanoparticles as lubricating oil additives, and modified CeO\({}_{2}\) and Cu nanoparticles using a suitable surfactant mixture to achieve good dispersion and stability in the lubricating oil. The special size, unique one-dimensional (1-D) tubular hollow and topology structure of carbon nanotubes make them attractive for various applications, including fabricating nanotubes reinforced nanocomposites on mechanical properties and tribological properties [15; 16; 17]. However, the insufficient dispersibility of carbon nanotubes deter their further research and development. The carbon nanotubes are acidified to have a partial oxygen-containing group on the surface to change their inertness. The modified carbon nanotubes are less likely to agglomerate and have increased solubility in solvent. Additionally, the modified carbon nanotubes are more easily combined with other materials during reaction. [PERSON] et al. [18] used carbon nanotubes containing a -COOH group as filling materials for polyimide, which showed significantly improved mechanical and tribological properties. [PERSON] et al. [19] prepared carbon nanotubes using a mixture of sulfuric acid and nitric acid. The experimental results showed that the dispersion of the modified carbon nanotubes in base oil is improved, and the antifriction and wear resistance of the modified carbon nanotubes are also enhanced effectively. Graphene oxide (GO), a two-dimensional (2-D) lattice, has numerous oxygen-containing groups and has superior thermal conductivity and mechanical properties. In addition, negative charge on the surface of GO makes it more convenient to combine with other materials without additional processing. As a new material, GO is widely used in various fields [20; 21; 22] such as tribology. [PERSON] et al. [23] used an electrokinetic spraying process to coat graphene oxide on silicon wafer in order to use the coating as solid lubricant. Results showed that the coating has better surface protection ability and lower friction coefficient. In recent years, many studies have confirmed that nano-hybrid materials can fully take advantage of various fillers and enhance the tribological properties of lubricating oil, polymers, and other materials [24; 25; 26]. [PERSON] et al. [27] prepared a self-lubricating graphene oxide/nano-MoS\({}_{2}\) hybrid using a three-step method and discussed the synergistic effect of self-lubricating and anti-wear properties of the hybrid. Results show that the friction coefficient and wear rate of the base oil decreased by 25% and 64%, respectively, after the addition of nanocomposites. [PERSON] et al.