Ti3C2Tx quantum dots achieve superior corrosion inhibition and lubrication via forming Ti–O–Fe coordination bonds: Experimental verification and computational investigation

Metal corrosion and mechanical wear result in a serious decrease in the service life of marine engineering equipment. Carbon-based quantum dots (CDs) are often used as corrosion inhibitors or lubricants due to their ease of functionalization and quantum size effect. However, the protection efficiency of CDs is limited by weak adsorption capacity, and additional doping of heteroatoms such as N and S is usually needed to enhance the adsorption. Here, Ti₃C₂T_x quantum dots (MQDs) were synthesized by using two-dimensional Ti₃C₂T_x sheets containing abundant functional groups on the surface as precursors. The corrosion inhibition efficiency of MQDs with a concentration of 400 mg L⁻¹ reached 94.2 %, and the coefficient of friction and wear rate were reduced by 67.6 % and 83.2 %, respectively, compared with the single NaCl solution. Surface analysis showed that MQDs blocked the penetration of corrosive species via forming a protective film on the steel surface through the formation of Ti–O–Fe coordination bonds. Notably, the thickness of protective film was affected by the pH of solution, reaching a maximum thickness of 215 nm at the NaCl solution with a pH of 7. Finally, density functional theory and molecular dynamics simulations were utilized to deeply reveal the adsorption mechanism of MQDs. This study provides new insights into the role of MQDs as dual-functional additives, which is of great significance in promoting the development of multifunctional marine engineering protective materials.