L-aspartic acid anchored on hierarchical assembly graphene-LDH nanohybrids for active anticorrosion of waterborne epoxy coatings

The labyrinth effect of graphene coatings could extend the diffusion path of corrosive media. However, the poor compatibility between graphene and resins and the low loading capacity of graphene affect its functional application. By combining the in-situ synthesis and electrostatic interaction, layered double hydroxides (LDH) were grown on the graphene surface, L-aspartic acid anions (Asp) were adsorbed on LDH by electrostatic interactions. The loading capacity of L-aspartic acid was up to 40.5 wt%. The barrier property of nanohybrid coatings was measured by electrochemical workstation, it was found that the rGO-LDH-Asp/epoxy coating exhibited the best corrosion protection properties, and the coating resistance could still be maintained at 1.231 × 10 9  Ω⋅cm 2 after being immersed in 3.5 wt% NaCl solution for 90 days. The anticorrosion mechanism of the coating was explored through local electrochemical impedance spectroscopy, L-aspartic acid anions adsorbed on the surface of rGO-LDH could accelerate the passivation of the metal substrate and delay the corrosion process.