Luminescent Carbon Dot-Graphene Oxide Epoxy Coatings: Enhanced Corrosion Protection and Detection

A new hybrid material-based approach leveraging luminescent hybrid carbon dots (CDs)-functionalized graphene oxide (CDs-f-GO) integrated into epoxy coatings has been developed for enhanced anticorrosion protection and real-time corrosion detection. This study introduces, for the first time, a one-step process for synthesizing CDs-functionalized GO, which has been thoroughly characterized by using Fourier transform infrared spectroscopy, UV-visible spectroscopy, and fluorescence spectroscopy, confirming successful functionalization. UV-visible spectra revealed a characteristic absorption peak at 335 nm for CDs-f-GO, while fluorescence spectroscopy demonstrated excitation-dependent fluorescence with a red shift from 445 to 472 nm, distinguishing it from nonfluorescent GO. Electrochemical characterization, including electrochemical impedance spectroscopy and Tafel analysis, confirmed the superior anticorrosion performance of epoxy-CDs-f-GO coatings. Corrosion resistance was evaluated over time in a 3.5 wt % NaCl solution, revealing significantly higher charge transfer resistance and lower corrosion current density for epoxy-CDs-f-GO compared to neat epoxy and other composite coatings. The hybrid material exhibited the highest corrosion protection on both days 1 and 7, maintaining minimal degradation over time. The salt spray test on scratched coatings further validated the effectiveness of epoxy-CDs-f-GO, as minimal corrosion blistering was observed, indicating strong resistance against electrolyte penetration. Additionally, the developed coating demonstrated dual functionality by enabling real-time failure detection under UV light. Prominent carving marks were visible on the epoxy-CDs-f-GO coating, suggesting its potential for early detection of cracks or defects in steel structures. The combination of enhanced corrosion resistance and proactive maintenance capability makes this material a promising candidate for industrial applications, particularly in marine and other highly corrosive environments.