Multielement-Doped Porous Carbon Nanosheets Derived from Metal–Organic Frameworks as Lubricating Additives for Antifriction and Antiwear Properties

The development of advanced lubricant additives is crucial for improving the tribological properties in mechanical systems. Doping has been certified as one of the effective methods for enhancing the lubricating properties of carbon nanomaterials. Herein, multielement (B, N, P)-doped porous carbon nanosheets (B, N, P@PCNs) were successfully prepared using ionic liquid-assisted pyrolysis of "copper-pyridine" coordination metal-organic frameworks (Cu-MOFs). The as-obtained B, N, P@PCNs exhibit good friction-reducing and antiwear behavior as lubricant additives. Compared to base oil 500SN, the friction coefficient was reduced to 0.104, resulting in a 77.5% decrease in wear volume, and the load-bearing capacity increased from 150 to 550 N simultaneously. Through Raman and XPS analysis, it was ascertained that the boron, nitrogen, and phosphorus elements actively participate in tribological chemical reactions, resulting in the formation of a protective film, which significantly mitigates wear and tear of friction pair by combining adsorption, restoration, and polishing mechanisms.