MXene-based anti-corrosive coatings: From physical barrier to active corrosion protection

Abstract

Coating is an effective method for protecting metals from corrosion, as it can prevent aggressive ions from penetrating onto metallic surface. However, pure anti-corrosive coatings are often susceptible to the formation of micropores and cracks during the preparation process and can be easily damaged by external environment factors during service, significantly reducing their protective capabilities. An effective strategy to address this issue is the incorporation of high-aspect-ratio, high stability two-dimensional (2D) materials, such as MXenes, into the coating. The “labyrinth effect” created by the lamellar 2D structure of MXenes forms a longer and more tortuous diffusion path, effectively blocking the longitudinal penetration of corrosive ions and enhancing the barrier performance of the coating. To further enhance the corrosion protection provided by MXene fillers in the coating matrix, modification treatments are necessary to improve the dispersion of the MXene fillers and the overall quality of the coating. These modifications can effectively reduce the diffusion paths of aggressive ions. Additionally, the high specific surface area of MXenes allows them to store corrosion inhibitors, enabling the slow release of these inhibitors for long-term corrosion protection. This review summarizes the application of MXene in anti-corrosive coatings, including physical barrier and active protection. We begin by discussing the preparation of single or few-layer 2D MXene fillers. Next, we examine the use of pristine or modified MXenes as passivation fillers to strengthen coating integrity. Furthermore, we explore the use of MXenes as supports for corrosion inhibitors to endow the anti-corrosive coatings with active protection capabilities. Finally, the future development directions for MXene fillers are prospected, and the challenges of enhancing the corrosion protection of organic coatings were discussed.