Controlled Oxidation of MXene for Regulating Tribochemistry at Sliding Interfaces

MXenes have emerged as promising solid lubrication additives due to their lamellar architectures and intrinsically low shear strength. During sliding, the role of MXene oxidation in tribochemical processes remains unclear. Here, we demonstrate that controlled oxidation provides an effective materials engineering strategy to regulate the interfacial tribochemistry of MXene. By precisely tuning the hydrogen peroxide (H₂O₂) to MXene ratio, oxidized MXene (oMXene) with uniform surface oxidation while preserving the layered structure is obtained. Under high contact pressures and elevated sliding velocities, oMXene undergoes friction-induced decomposition accompanied by interfacial reconstruction, leading to the in situ formation of a robust dual-phase tribofilm consisting of highly graphitized carbon and titanium-based oxides. This tribochemical reconstruction fundamentally alters the dominant interfacial shear and load-bearing mechanisms, thereby resulting in pronounced and durable reductions in friction and wear in steel-steel contacts. These findings establish controlled oxidation as a key parameter governing MXene interfacial reconstruction and offer a rational pathway for the design of high-performance lubrication additives.