Facile synthesis of morphology and size controlled a Fe2O3 and Fe3O4 nano and microstructures by hydrothermal/solvothermal process: The roles of reaction medium and urea dose
Abstract This paper reports a systematic study of the influences on the synthesis of a Fe 2 O 3 and Fe 3 O 4 via a hydro/solvothermal process at 200 degC. Both the reaction medium and urea dose have been investigated. The products were characterized by X ray diffraction (XRD) Fourier transform infrared spectroscopy (FT IR) scanning electron microscopy (SEM) transmission electron microscopy (TEM) Results showed that the reaction mediums, such as water and ethylene glycol, played important roles in forming different types of iron oxides. Pure crystalline a Fe 2 O 3 was formed via the hydrothermal process, and Fe 3 O 4 was obtained through a solvothermal route with ethylene glycol as reaction medium. Increasing urea dose tuned the particle sizes of a Fe 2 O 3 and Fe 3 O 4 from a few hundreds to several tens of nanometers. With addition of urea, the morphology of a Fe 2 O 3 evolved from olive like to rhomb like, and Fe 3 O 4 evolved from hollow sphere, to pinecone like, and finally into cracked nanostructures. The variations of the surface area of products were mainly dependent on the microstructure and intrinsic features of the iron oxide particles. Results of the mechanistic studies indicated that the generation of CO 2 and NH 3 via in situ thermal decomposition of urea was crucial for the formation of a Fe 2 O 3 and Fe 3 O 4 nano and microstructures. The as synthesized a Fe 2 O 3 and Fe 3 O 4 were used as catalysts for methylene blue degradation in the presence of H 2 O 2 and a Fe 2 O 3 showed a higher degradation efficiency. Our findings demonstrated a promising strategy for the developments of rationally designed iron oxides.