Synthesis of N-doped carbon quantum dots as lubricant additive to enhance the tribological behavior of MoS2 nanofluid

Abstract In this study, a novel lubricant additive nitrogen-doped carbon quantum dot (N-CQD) nanoparticle was prepared by the solvothermal method. The synthesized spherical N-CQD nanoparticles in diameter of about 10 nm had graphene oxide (GO)-like structure with various oxygen (O)- and nitrogen (N)-containing functional groups. Then N-CQDs were added to MoS 2 nanofluid, tribological properties for steel/steel friction pairs evaluated using pin-on-disk tribometer. Non-equilibrium molecular dynamics (NEMD) simulations system or MoS2 + also conducted. results showed that processes nanofluids under mixed lubrication regime. And nanofluid containing 0.4 wt% could achieve 30.4% 31.0% reduction coefficient wear rate, respectively, compared those without N-CQDs. By analyzing worn surface topography chemical compositions, excellent performance resulted from formation tribochemistry-induced tribofilm. average thickness tribofilm 13.9 nm, it composed amorphous substances, ultrafine crystalline nanoparticles, self-lubricating FeSO 4 /Fe (SO ) 3 . NEMD simulation indicated interaction between S atoms as well these O- N-containing groups steel surfaces enhanced stability strength Thereby metal further protected wear.