Berberine-Functionalized Graphene Oxide Nanocomposite for Enhanced Corrosion Protection of Epoxy-Coated Copper in Marine Environments

This study introduces a novel anticorrosion coating for copper based on an epoxy matrix reinforced with a berberine-loaded graphene oxide (BBR@GO) nanocomposite. The BBR@GO was synthesized via a simple, non-covalent functionalization method, leveraging π-π stacking interactions between the planar berberine molecule and the graphene oxide surface. The successful loading of berberine was confirmed by Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and energy-dispersive X-ray spectroscopy (EDS). The BBR@GO nanocomposite was incorporated into an epoxy resin at 0.1 wt.% loading and applied to a copper substrate. The corrosion protection performance of the BBR@GO/EP coating was systematically evaluated in 3.5 wt.% NaCl solution for 27 days using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). The BBR@GO/EP coating exhibited a total impedance of 5.31 × 108 Ω·cm2 after 27 days, which was 17 times higher than the pure epoxy (EP) coating. The corrosion current density (icorr) was reduced to 2.59 × 10−8 A·cm−2, a four-fold decrease compared to the EP coating. Post-immersion analysis confirmed the excellent durability of the BBR@GO/EP coating and the retention of berberine within the matrix. The enhanced performance is attributed to the synergistic effect of the physical barrier provided by the well-dispersed GO nanosheets and the inhibitive action of the retained berberine molecules at the coating–metal interface.