A hydrophobic high-crystalline g-C3N4/epoxy resin composite coating with excellent durability and stability for long-term corrosion resistance

Through a creative combination of solar-driven photo-generated electron cathodic polarization effects and the barrier nature of two-dimensional (2D) materials, highly crystalline g-C3N4 (HCCN) nanosheets were developed and applied in the anti-corrosion performance test in this work. Coupling HCCN with epoxy resin (EP) effectively forms a hydrophobic HCCN/EP composite coating with a water contact angle of 103 & DEG;. Experimental results reveal that the electrochemical impedance of the HCCN/EP coating (3.68 x109 L'1 & BULL;cm2) rose by three orders of magnitude in a 3.5 wt% NaCl solution compared to the EP coating (3.69 x106 L'1 & BULL;cm2). In addition, the electric polarization curves demonstrated that the corrosion current of HCCN/EP coating (3.72 x10-9A & BULL;cm- 2) was lowered by roughly two orders of magnitude compared to the EP coating (2.75 x10-7 A & BULL;cm-2). Moreover, the long-term anti-corrosion tests demonstrated after 30 days of immersion test, and no prominent corrosion areas were found on the surface of HCCN/EP, indicating excellent corrosion resistance durability. Furthermore, adding g-C3N4 nanosheets strengthened the adhesion grade of the EP coating from 3B to 5B, attributing to the formation of hydrogen bonds between g-C3N4 nanosheets and EP as well as on the carbon steel surface.