Structure and performance insights in carbon dots-functionalized MXene-epoxy ultrathin anticorrosion coatings

Abstract

• A novel CD-Ti 3 C 2 T x was synthesized to efficiently protect sensitive MXene from oxidation and deterioration. • The self-aligned B-CM-EP coating with CD-Ti 3 C 2 T x was prepared through a facile flow-induction strategy. • The self-aligned parallel arrangement CD-Ti 3 C 2 T x enhanced greatly the anticorrosion performance of coating. • The CD-Ti 3 C 2 T x endowed the coating with a superior passivation property. • The highly distributed and orientated CD-Ti 3 C 2 T x completely inhibited the corrosion-promotion activity of MXene. MXene nanosheets have showed potential application in metal protection fields due to their large specific surface area and superior mechanical properties. However, MXene for anticorrosion is still underdeveloped, and some associated matters involving susceptibility to oxidation as well as corrosion-promotion activity derived from high conductivity need to be solved. Herein, we use carbon dot (CD) to functionalize Ti 3 C 2 T x MXene nanosheets via Ti-O-C bonding to obtain CD-Ti 3 C 2 T x hybrids, which significantly improves the chemical stability of MXene in water. Then a flow-induced approach is introduced to construct CD-Ti 3 C 2 T x reinforced epoxy (EP) composite coatings, in which CD-Ti 3 C 2 T x is self-aligned to form an oriented layered structure. The unique structure endows the EP coatings with outstanding anticorrosion performance, and more than 4 orders improvement in impedance modulus at an ultrathin thickness of ∼ 25 μm, and 2 orders much higher than random-dispersed composites with the same fillers content. Besides, the CD also provides additional passivation effect to efficiently suppress crack and local damage propagation. More importantly, the parallel arrangement CD-Ti 3 C 2 T x platelets can inhibit the corrosion-promotion activity by eliminating connections of MXene/MXene and MXene/metal in vertical direction, which will further improve the stability and durability of coatings. This work provides a novel strategy to realize chemically stable MXene and inhibit the corrosion-promotion activity of MXene-based coatings, which possess a combination of anticorrosion performance and passivation effect that are suitable for heavy-anticorrosion applications in harsh sea environment.