Carbon Dots@Ti3C2Tx -MXene 0D/2D Hybrid Composites toward High-Performance Lubricating Additives under Varying Temperatures

Progress in nanolubricant additive is crucial to pursuit of energy saving and sustainable development. For enhancing lubrication efficiency of pentaerythritol ester (PETE) oil, we synthesized zero-dimensional/two-dimensional (0D/2D) carbon dots(CD)@Ti3C2Tx-MXene hybrid composites using a facial hydrothermal method, which gave full play to interlayer shear mechanism of Ti3C2Tx-MXene, repair effect of carbon dots and their potential synergy. The composites were added to PETE as lubricating additives, during which ultrasonic treatment was employed to enhance the dispersion stability. The frictional tests confirmed that the addition of CD@Ti3C2Tx resulted in significant reductions in friction and wear across varying temperatures owing to the ultrasmall size, interlayer sliding, and synergistic effect. The optimal concentration of 0.1 wt % of CD@Ti3C2Tx reduced friction coefficients and wear volumes of PETE by 54.5% and 57.6% at 25 degrees C, 53.3% and 54.3% at 100 degrees C, and 40.0% and 45.9% at 200 degrees C, respectively. A tribofilm induced by complex tribochemical reactions, mainly consisting of carbon dots, Ti3C2Tx, metal oxides, carbides, and nitrides, was generated at the contact interface, which significantly alleviated direct contact between the rubbing pair. This study explores the potential of CD@Ti3C2Tx for development of advanced lubricating materials and is expected to contribute to wider adoption of MXene-based materials in the field of tribology.