Eco-Friendly Preparation of Rod-like CeO ₂ Nanoparticles and Their Use as High-Performance Lubricant Additives

Crystalline rod-like CeO2 nanoparticles (NPs) are well-known as lubricant additives. They are prepared by using various cumbersome wet-chemical methods that are not industrially feasible for large-scale production. This study reports an easy, nitrate-assisted, surfactant-free, and eco-friendly method for the preparation of rod-like CeO2 NPs. The formation of highly crystalline rod-like CeO2 NPs is confirmed by various characterization techniques. The prepared rod-like CeO2 NPs are then used as additives in lubricating oil to improve lubricity. Using rod-like CeO2 NP-added lubricant in tribological tests reduces the coefficient of friction and wear by 45% and 35%, respectively, indicating enhanced lubricity. This improvement is attributed to the excellent dispersion of rod-like CeO2 NPs in the lubricant, which creates a protective barrier and reduces friction between sliding surfaces. However, these qualities deteriorated at higher concentrations, suggesting a threshold above which the benefits diminish. Using rod-like CeO2 NPs as lubricant additives results in a remarkable 45.3% reduction in energy loss compared to the base oil at the same temperature. The rod-like CeO2 NPs used as lubricant additives are projected to achieve an annual CO2 emission reduction of 67–100 kg per vehicle. The findings provide valuable insights into developing rod-like CeO2 NPs as lubricant additives to enhance durability and efficiency.