Investigation on outstanding corrosion protection property of waterborne epoxy coating enabled by nanocrystalline cellulose-dispersed g-C3N4 nanosheets

In this work, a waterborne-based epoxy composite coating with great anticorrosive capability was developed by applying an ultrasonic aqueous mixture of nanocrystalline cellulose (NCC) and graphitic carbon nitride (g-C 3 N 4 ) nanosheets as an ideal reinforcing nanofiller for metallic surface prevention against corrosion. The characterization results demonstrated that g-C 3 N 4 nanosheets acquired outstanding aqueous dispersion and displayed a homodisperse state in epoxy matrix after ultrasonic process with NCC, providing efficient barrier performance for epoxy coating to block the corrosive substances’ ingress. The electrochemical impedance spectroscopy (EIS) measurement outcome revealed that epoxy coating with the incorporation of NCC and g-C 3 N 4 nanohybrids (g-C 3 N 4 @NCC) held at the impedance value of 7.338 × 10⁶ Ω·cm² through the 40 days-immersion process, which improved by an order of magnitude by contrast with original epoxy coating. Besides, the results of salt spray test confirmed that the g-C 3 N 4 @NCC composite coating with artificial scratch accumulated the least amount of corrosion products in high-concentration salt fog conditions, remaining consistent with the anti-corrosion effectiveness trend obtained from EIS.