Zirconium-Doped Ceria Nanoparticles as Anticorrosion Pigments in Waterborne Epoxy–Polymer Coatings

The use of anticorrosion pigments in polymeric coatings is an effective way for the prevention of corrosion of metals. Ceria nanoparticle-based pigments are excellent replacement for conventional chromate-based inhibitors that create severe toxicity and health hazards. The corrosion inhibition mechanism of ceria is associated with its Ce4+ ↔ Ce3+ redox shuttle and ability to form insoluble precipitates over the metallic substrate. Zirconium doping in ceria can enhance its redox properties by creating a large number of oxygen vacancies. However, corrosion inhibition properties of zirconium-doped ceria are not studied yet. In the present work, ceria–zirconia solid solutions (CexZr1–xO2 nanoparticles) with different doping concentrations of Zr have been prepared using coprecipitation synthesis. X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy studies revealed the formation of ceria–zirconia solid solutions with increased oxygen defect density. Thermogravimetric analysis exhibited enhanced oxygen storage capacity for Ce–Zr solid solutions. CexZr1–xO2 nanoparticle-filled waterborne epoxy resin coating has been prepared on a mild steel substrate using the spin-coating technique. Electrochemical corrosion measurements were employed to analyze the corrosion inhibition properties of the coatings. Tafel polarization results and electrochemical impedance spectroscopy analysis show excellent corrosion resistance for zirconium-doped ceria nanoparticle-filled epoxy coating. The corrosion resistance of the zirconium-doped ceria-epoxy coating increased with an increase in the doping concentration of Zr for Ce-rich Ce–Zr solid solutions (0.6 ≤ x ≤ 0.8). The corrosion inhibition property of ceria–zirconia solid solutions is attributed to the improvement in their redox properties due to a large number of oxygen vacancies.