One-Step In Situ Electrochemical Synthesis of Polyaniline/CeO₂ Composite Coating for Enhanced Corrosion Protection of Mild Steel

The electrolytic composition significantly influences the structure and corrosion protection performance of polyaniline (PANI) coating. In the present work, oxalic acid and benzoic acid were employed to electropolymerize PANI coating on a mild steel substrate using the cyclic voltammetry (CV) technique. Then, cerium nitrate was introduced into the benzoic acid medium to electrochemically synthesize a PANI/CeO₂ composite coating in situ. Scanning electron microscopy, X-ray photoelectron spectroscopy and electrochemical measurements were used to characterize the coating structure and corrosion resistance. The results suggested that the PANI coating prepared from benzoic acid electrolyte possessed a neater structure and better anti-corrosive properties. The co-deposition of CeO₂ further increased the thickness and improved the compactness of the PANI coating. The synthesized PANI/CeO₂ composite coating possessed the smallest corrosion current density and the largest inhibition efficiency of 98.2%. The charge transfer resistance and coating resistance also increased significantly after the implantation of CeO₂ in the PANI coating. The enhanced corrosion protection performance of the PANI/CeO₂ hybrid was also elucidated.