Waterborne epoxy composite coating containing N,S-doped carbon dots for enhancing corrosion resistance

In order to construct waterborne epoxy composite coating with enhanced anti-corrosive performance, the development of efficient additives with good compatibility with adhesive resin and good interaction with steel matrix is of significance. Herein, we adapted two heteroatom (N and S) doped carbon quantum dots, namely ACDs and LCDs, as eco-friendly anti-corrosion components to mix with water-based epoxy resin (WP) to prepare the CDs/WP composite coating. Compared with the ACDs/WP composite, the LCDs/WP composite exhibited a better performance because it contained more functional groups such as carboxyl and hydroxyl on the surface of LCDs, which not only made the system denser but also facilitated the multi-anchor coordination and adsorption on carbon steel. Following immersing in a 3.5 wt% NaCl solution for 28 d, the impedance modulus of LCDs/WP surpassed 109 Ω cm2, exhibiting approximately three orders of magnitude higher values compared to pure WP coatings. The inhibition efficiency was improved by 96.9%. The facile synthesis of LCDs coupled with excellent anti-corrosive properties of LCDs/WP composites, provides a new way for developing anti-corrosion coating materials.