To enhance the corrosion resistance of epoxy coatings, a three-dimensional (3D) network-like europium–nickel-co-doped zinc oxide (Eu–Ni–ZnO) was synthesized via a combustion method. The unique 3D network structure physically blocks corrosive medium penetration by creating a tortuous diffusion pathway. Electronic coupling between Eu3+ 4f and Ni2+ 3d orbitals forms “charge carrier traps” that promote charge carrier separation. Oxygen vacancies further capture electrons from anodic dissolution to suppress cathodic reduction. Additionally, Ni3+ provides a strong oxidizing capability to oxidize Fe2+ into Fe3+, facilitating the formation of a passivation layer on the metal surface. The electrochemical tests revealed that the impedance modulus of the Eu–Ni–ZnO-4/epoxy resin coating increased 884.9% than that of the Blank/epoxy resin coating and 579.6% than that of the ZnO/epoxy resin coating. This study transforms ZnO from an inert filler into an electrochemically active barrier, offering a new strategy for durable anti-corrosion coatings.
Wang et al. (2026) studied this question.