Synthesis and characterization of cerium oxide/iron oxide nanocomposite and its surface acid-base characteristics

The acid-base behavior on nanoparticles' surface played an important role in chemical reactions related to catalysis, adsorption, and corrosion resistance. Exploring the characteristics of equivalent to FeOH on the surface of nanoparticles was helpful to study the acid-base behavior of the surface of nanoparticles. It provided a basis for the development of new surface active materials. In this study, cerium oxide/iron oxide nanocomposites were synthesized by physical blending method (PBM-CION) and hydrothermal method (HM-CION). HM-CION had lattice distortion, while PBM-CION was only physical adsorption, and the crystal structure had not changed significantly. The band gap of HM-CION was significantly reduced to 2.16 eV and it's equivalent to FeOH concentration was 1.9 times and 1.3 times of that in PBM-CION and Bayer iron oxide. Therefore, it had a strong acid-base buffering capacity in the solution, so HM-CION had potential application value in catalysis, adsorption, and anticorrosive coating. HM-CION mainly undergone equivalent to FeOH protonation reaction, and the equilibrium constants of equivalent to FeOH protonation and deprotonation reactions are -4.40 and -213; 8.22, respectively.