Ce-doped α-Fe_2O_3 nanoparticles prepared by hydrothermal method used in corrosion-resistant field: effects of pH on the structure, morphology and chemical stability

摘要

Ce-doped α-Fe_2O_3 nanoparticles were successfully synthesized by hydrothermal method at different pH. The relationship between the pH of the solution and the morphology, structure and electrochemical stability of the prepared Ce-doped α-Fe_2O_3 nanoparticles was investigated by X-ray diffraction, transmission electron microscopy, scanning electron microscope, Fourier transform infrared, X-ray photoelectron spectroscopy, electrochemical methods and saltwater immersion experiment. The results showed that the Ce-doped α-Fe_2O_3 nanoparticles prepared at pH = 4 and pH = 6 had surface defects structure, and the Ce-doped α-Fe_2O_3 nanoparticles prepared at pH = 8 had adhesion structures, which were CeO_2 nanoparticles adhered to the α-Fe_2O_3 nanoparticles' surface. The fact that Ce ions could be readily doped into the α-Fe_2O_3 lattice, causing lattice distortion and increasing the binding energy of Fe~(3+) in the lattice, thereby enhancing the stability of Fe-O bonds correspondingly. At the same time, the surface defect structure is produced, which has the effect of promoting the compactness of the coating. The surface defects structure of α-Fe_2O_3 has stronger electrochemical stability than the adhesion structure of α-Fe_2O_3 and Bayer α-Fe_2O_3. It was found that waterborne acrylic coatings prepared from of α-Fe_2O_3 with surface defects structure had a stronger hindering effect on the diffusion of charged ions.