Correlating the effect of preparation methods on the structural and magnetic properties, and reducibility of CuFeO catalysts.

CuFeO spinel oxide has attracted research interest because of its versatile practical applications, especially for catalysis. In this study, nanometre-sized CuFeO particles were prepared by three different methods, including nanospace confinement in SBA-15, hard template removal, and sol-gel combustion. The relationship between structure, size, magnetic behaviour, and reducibility of the catalysts was further investigated by various advanced techniques. Samples prepared by impregnation and hard template removal show high surface area and small crystallite size with superparamagnetic behaviour. In contrast, the sol-gel sample exhibits ferromagnetic properties with a large crystallite size and low surface area. Although all samples present a tetragonal crystal structure, the distributions of Fe and Cu cations in tetrahedral and octahedral sites in the spinel structure are different. The reducibility results demonstrate that the supported CuFeO/SBA-15 shows the lowest reduction profile. These results could suggest that the synthesis method strongly affects the crystal properties and cation distribution in the spinel structure, microstructure, surface area and reducibility, which are among the most relevant physicochemical properties for the catalytic activity.