Designing a dual-functional material with barrier anti-corrosion and photocatalytic antifouling properties using g-C3N4 nanosheet with ZnO nanoring

• ZnO nanoring loaded on the 2-C3N4 nanosheets was synthesized by chemical etching technology. • NR ZnO-CNNs displayed excellent photocatalytic antifouling ability to chlorella and B. subtilis. • ZnO nanoring loaded on the g-C enlianced the compatibility between epoxy and 2-C3N4 nanosheets. • NR ZnO-CNNs can effectively enhanced the long-term corrosion resistance of epoxy resin. As a semiconductor material with a 2D-laminate structure, g-C 3 N 4 (bandwidth 2.7 eV) has a similar structure and excellent performance to graphene. However, high surface energy and photogenerated e–h recombination of g-C 3 N 4 seriously hinder its application in the field of marine anticorrosion and antifouling. To solve these problems, we synthesized the g-C 3 N 4 nanosheets decorated with ZnO nanoring via chemical etching technology. Whether the NR ZnO-CNNs have surface protection performance among the pure EP on the corrosion protection for metal substrate were investigated. The antifouling properties NR ZnO-CNNs hybrid were also estimated through photocatalytic bacterial and algae resistance tests. Combined with the electrochemical results, it was found that the impedance modulus of NR ZnO-CNNs/EP within 45 days showed two orders of magnitude higher than that of pure EP in the 3.5 wt% NaCl solution. Besides, Local electrochemical impedance spectroscopy (LEIS) further explored the anticorrosion behavior of NR ZnO-CNNs/EP coating, which indicated that the NR ZnO-CNNs/EP coating with a scratch maintained an excellent corrosion resistance between 0–24 h. Under the visible light conditions, the lifetime of photogenerated e–h was prolonged due to the formation of NR ZnO-CNNs heterojunction structure, it was observed that the antibacterial rate against Bacillus subtilis reached 100% within 8 h. An Antialgae test was performed on chlorella seawater solution, which indicated that 5 mg/mL of NR ZnO-CNNs hybrid could make chlorella sharply reduce within 4 days. Simultaneously, the corrosion protection and photocatalytic antifouling mechanisms of NR ZnO-CNNs were proposed, thus it provided a broader platform for the design of versatile marine protection materials. NR ZnO-CNNs composite was prepared via chemical etching technology, and its excellent corrosion resistance to Q235 steel substrate in epoxy resin matrix was detected by electrochemical measurement. Simultaneously, NR ZnO CNNs also had excellent inhibition effect on Chlorella and Bacillus subtilis under the photocatalytic antifouling test.