Toward self-healing two dimensional MXene coatings for corrosion protection on metals: Design strategies and mechanisms

Metallic corrosion leads to high economic losses and security risks, and coating protection is an effective approach to preventing metal from corrosion. However, defects such as cracks and micropores are inevitable in the coating, so it is urgent to develop self-healing coatings for realizing long-term corrosion protection due to the actively protective ability. Though two-dimensional (2D) transition metal carbide or nitride (MXene) coatings have been employed to realize self-healing function, the design strategies of the MXene-based coatings and mechanism on how MXenes inhibit corrosion at the coating-metal interface as well as the roles of MXene in self-healing process remain elusive. In this review, the traditional self-healing coatings and the mechanisms were briefly introduced. Subsequently, the MXene and its anti-corrosive property were discussed. Then, the design and properties of self-healing MXene coatings (synergy with Ce³⁺, layered double hydroxide, inhibitors, and self-healing polymer) were further discussed. Importantly, the currently proposed self-healing mechanisms of the MXene coatings were summarized and analyzed. Finally, the challenges and prospects for the self-healing MXene coatings were proposed. This review can provide guidance of designing and understanding the mechanisms of the self-healing MXene coatings. It would expand the practical application of 2D MXene on corrosion protection.