Enhancing the corrosion resistance of waterborne epoxy coatings with functionalized biochar

Abstract

This study utilizes discarded tree leaves as a substrate to synthesize biomass porous carbon nanosheets (PCNS) through high-temperature carbonization and pore-forming treatment, followed by functional modification using carboxymethyl chitosan (CMCS) and the corrosion inhibitor 8-hydroxyquinoline (8-HQ). The functionalized PCNS fillers were incorporated into water-based epoxy (WEP) coatings to enhance corrosion resistance. Electrochemical impedance spectroscopy (EIS) testing showed that after 60 days, WEP/PCNS@CMCS@8-HQ exhibited a low-frequency impedance of 1.7 × 10⁹ Ω cm² at the lowest frequency, with significantly improved salt spray corrosion performance compared to WEP. The study demonstrates that CMCS effectively captures Cl⁻ and acts as a repair agent, working synergistically with the external corrosion inhibitor 8-HQ to improve the dispersion of PCNS within the WEP matrix and enhance corrosion resistance. These findings indicate that green-modified PCNS offers a promising approach to improving the corrosion resistance of coatings.