Fabrication of N/P-codoped carbon dots with anti-bacterial activity for enhanced aqueous lubrication performance

To address energy wastage caused by friction, it is urgently needed to develop multi-functionalized nano-additives based on traditional lubricant additives. Herein, nitrogen/phosphorus co-doped carbon dots (N,P-CDs) are successfully prepared via one step hydrothermal method using benzopyrrole as raw materials and diethylenetriaminepenta as N, P-dopant. The prepared N,P-CDs demonstrate good lubrication effects when used as water-based additives. Compared with pure H₂O, the coefficient of friction (COF) significantly decreases from 0.448 to 0.144, accompanied by a notable reduction in wear volume from 3.84 × 10⁵ μm³ to 2.31 × 10⁵ μm³. This is attributed to the formulation of the robust hydration layer on the CDs surface, as well as the tribochemical protective film generated on the friction pair surface. In addition, the introduction of N,P-CDs effectively inhibits bacterial growth during long-term storage of H₂O as lubricant. With small additions (100 μg/mL), the anti-bacterial rates against Escherichia coli and Staphylococcus aureus could reach 94.9 % and 99.5 %, respectively.