Porous 2D Ti3C2 MXene nanosheets sandwiched between imine-based covalent organic frameworks (COFs) for excellent corrosion protective coatings

MXene nanosheets have recently been the research hotspot for corrosion applications thanks to their 2D sheet-like structure and unique built-in physicochemical properties. However, they are prone to restacking and oxidation, narrowing down their final application. On the other hand, even highly exfoliated MXene does not possess a large surface area, which is desirable for self-healing and protective coatings. Thus, this study proposes a tailored hybrid skeleton by the in-situ growing of a highly porous covalent organic framework (COF) on the MXene nanosheets to avoid oxidation and restacking and, at the same time, enhance the MXene surface area. Such an advanced structural design is crucial for corrosion protective coatings since a sheet-like structure improves the barrier properties, while a large porous surface area is desirable for hosting corrosion inhibitors to provide self-healing features. As proof of concept, an imine-based COF was grown on the MXene nanosheet via an in-situ method, resulting in a 128 m2.g−1 surface area. Subsequently, loading zinc and glutamate molecules as inorganic and organic inhibitors into porous MXene nanosheets resulted in 88 % corrosion mitigation in the long term (96 h), which is promising among counterparts. Moreover, introducing this novel nanoplatform into an epoxy coating provided self-healing properties with more than 200 % active corrosion prevention improvement compared to the unfilled coating. Additionally, the proposed epoxy nanocomposite showed 10.64 Ω.cm2 for Log|Z|10 mHz term after 11 weeks in a 3.5 wt% saline solution, representing no electrolyte diffusion over a long period. In brief, this work proposes not only a novel structural design for superior anti-corrosion coatings but also a concept that has the potential to be applicable in various MXene-related areas.