Fabrication of carbon dots intercalated MXene hybrids via laser treatment as oil-based additives for synergistic lubrication

As an emerging two-dimensional material, MXene exhibits excellent anti-friction and anti-wear properties in lubrication systems. However, as an oil-based lubricant additive, their stable dispersion in base oil still faces great challenges. Optimizing the microstructure has been proved to be an effective strategy to improve the stable dispersion of MXene in base oil. In this work, catechol groups functionalized carbon dots are synthesized successfully by pulsed laser irradiation of tannic acid in acetone, and then they are grafted onto MXene surface to obtain MXene@CDs hybrids via chemical bond between catechol groups of carbon dots and Ti–OH of MXene surface. Carbon dots not only increase the layer spacing of MXene nanosheets, reduce self-weight stacking, but also make it easier to slide between layers. When used as oil based lubricating additives, MXene@CDs can reduce the coefficient of friction of PAO 10 from 0.58 to 0.1, and the wear volume is reduced by 91.3%. Due to the shear-induced and self-healing mechanism, the special intercalation structure of MXene@CDs is easily formed a protective film during the run-in period, which not only reduces the contact area of friction couples but also eliminates the polishing effect on the substrate surface, thus enabling synergistic lubrication.