N-doped Carbon Quantum Dots with Mechanical Enhancement and Fluorescence Properties Toward Anti-Corrosion Coating

To improve the anti-corrosion performance and mechanical properties of waterborne epoxy, we synthesized new N-CQDs and introduced them into the coating to prepare N-CQDs/EP. Based on SEM, Micro FT-IR, EIS, NSS, adhesion Tester, and LSCM, the long-term corrosion resistance, mechanical, and fluorescence properties of N-CQDs/EP were studied carefully. The cross-sectional SEM results indicated that N-CQDs could improve the internal cross-linking density and reduce the pore size of N-CQDs/EP. EIS results showed that composite coating could provide excellent anti-corrosion to steel in both 3.5 wt% NaCl solution and simulated seawater. The highest impedance value of N-CQDs/EP was still maintained at 10 9  cm 2 after 30 d immersion. N-CQDs also enhanced the adhesion force, and the highest value was 6.8 MPa. Meanwhile, the N-CQDs/EP fluorescence intensity was increased with the appearance of N-CQDs. Hence, this work can provide theoretical support for developing new epoxy coatings and accelerate the industrial application of long-term coatings.