Functionalized N-doped carbon nanosheets derived from metal-organic framework as oil-based lubricant additives for improved tribological performance

Herein, the functionalized N-doped carbon nanosheet (N@PCNs) was successfully achieved through pyrolysis of metal-organic framework (MOF) and then surface modification with anti-wear agent. Firstly, the N@PCNs was obtained via carbonization of copper pyridine coordination polymer-based MOFs. Then tannic acid (TA) crosslinked by polyethylenimine (PEI) via Michael addition was grafted on the N@PCNs surfaces. Finally, the antiwear agent 2,5-dimercaptothiadiazole dimer (DTD) was grafted onto N@PCNs via Michael addition reaction with TA to obtain DTD-N@PCNs. The average COF of 500SN decreases to 0.110 from 0.195, accompanied by 69.3% reduction in wear volume with 1.00 wt% DTD-N@PCNs addition. The lubrication performance is ascribed to the formation of a stable protective film through DTD-N@PCNs facilitating tribochemical reactions, preventing direct contact of the ball-disc pairs.