Preparation of active–passive anticorrosion antistatic epoxy nanocomposite coatings loaded with CeO2, CeO2@C, and CHS particles

In this study, active–passive anticorrosion antistatic epoxy composite coatings containing CeO₂, carbon coated ceria (CeO₂@C), and carbon hollow sphere particles were prepared. Cerium oxide (CeO₂) particles were synthesized through a hydrothermal approach in the presence of polyvinylpyrrolidone as a surfactant to achieve a uniform and semispherical morphology and to improve dispersion stability. Carbon hollow spheres (CHSs) were also fabricated using the surface-modified silica templating method. The structure and morphology of the synthesized particles were analyzed using Fourier transform infrared spectrometry, X-ray diffractometry, Raman spectrometry, and scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM-EDS). Furthermore, migration of the synthesized particles from the bulk toward the surface was investigated with atomic force microscopy, Raman spectra, and field emission SEM in addition to density, capillary wetting, contact angle, and zeta potential measurements. The results indicated that CHSs migrate toward the surface of the matrix due to its low interfacial tensions leading to a decline in the dielectric constant and electrical resistance, providing a composite with suitable antistatic properties. Moreover, electrochemical impedance spectroscopy and immersion testing were used to estimate the influence of the particles on the coating's anticorrosive property. The results showed that the impedance modulus at low frequency (|Z|0.01 Hz) significantly increased from 3.81 × 10⁶ Ω cm² (pristine epoxy) to 11 × 10⁸ Ω cm² after 40 days of immersion in 3.5% NaCl water solution. As a result of the synergistic protection provided by ceria, CHS, and CeO₂@C particles, composite coatings exhibit superior anticorrosion properties. The ceria particles have an inhibitory effect which forms a passive layer. Furthermore, the CHS and CeO₂@C particles produce a protective barrier prolonging the penetration pathway of corrosive media. Such significant improvements can provide an antistatic coating for designing novel corrosion protection coatings.

Graphical abstract