One-pot hydrothermal-prepared highly electronegative ZrP-rGO nanomaterial: Enhancing corrosion resistance of low-zinc coatings by inhibiting chloride ion permeation

In the marine environment, chloride ion is the main reason for the accelerated corrosion of carbon steel. Meanwhile, in zinc-containing coatings, the chloride-bearing corrosion product Zn 5 (OH) 8 Cl 2 ·H 2 O exhibits a theoretical volume expansion rate as high as 260%, which easily precipitates coating cracking. In this study, a two-dimensional zirconium phosphate-reduced graphene oxide (ZrP-rGO) nanomaterial with a highly negative potential surface was fabricated. Its two-dimensional architecture significantly prolongs the diffusion pathways of corrosive species. Moreover, the highly negatively charged surface generates strong electrostatic repulsion against chloride ions, effectively acting as a selective ionic barrier. This dual action suppresses the formation of high-volume-expansion zinc corrosion products (e.g., Zn₅(OH) 8 Cl 2 ·H 2 O), thereby preserving coating integrity and enabling zinc in low-zinc coatings to fully exert its chemical shielding effect. Specially，after 30 days of immersion, the coating with 1 wt% ZrP–rGO show a |Z| 0.01Hz of 3.32 × 10 8  Ω·cm 2 and a corrosion current density of 2.65 × 10 −10 A·cm −2 , as confirmed by EIS and Tafel analyses. These values are five orders of magnitude higher and four orders of magnitude lower than those of a pure 60 wt% zinc coating, significantly enhancing the coating's corrosion resistance. Salt spray testing demonstrates that the 1 wt% ZrP-rGO coating exhibits excellent corrosion resistance. This work provides new insights into improving the corrosion resistance of zinc coatings.