Synthesis of bimetallic aluminum-iron oxide nanorice, nanocubes and nanospheres

Bimetallic oxide nanoparticles are promising materials due to their diverse physical properties. Herein, we synthesized bimetallic aluminum oxide (AlOx)-iron oxide (FeOx) nanoparticles with different shapes and elemental compositions by tuning the low-temperature solvothermal reaction conditions. Bimetallic oxide nanoparticles with three different geometries (nanorice, nanocubes, and nanospheres) were obtained by varying the ratio of aluminum oleate and iron oleate precursors in 1-octanol. The concentration of iron oleate precursor in the reaction medium played an important role for the shape evolution of bimetallic oxide nanoparticles. A detailed understanding of the synthesis process and the physicochemical properties of the synthesized nanoparticles was obtained using various techniques, including high-resolution transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). XRD analysis revealed the presence of hematite (Fe2O3) in all nanoparticles, regardless of the shape or size. However, the Al composition of nanoparticles increased as the aluminum oleate precursor concentration was increased in the reaction medium. Furthermore, the as-synthesized bimetallic nanoparticles contained AlOx, which was transformed into & gamma;-Al2O3 and & alpha;-Al2O3 following high-temperature annealing, whereas the crystallinity of Fe2O3 was maintained.