Fast production of self-assembled hierarchical α-Fe2O3 nanoarchitectures

A fast and economical route based on an efficient microwave-assisted hydrothermal process has been developed to synthesize self-assembled hierarchical alpha-Fe2O3 nanoarchitectures on a large scale. This new method reduces the synthesis time from days to minutes, allowing the screening of a wide range of reaction conditions for optimizing and scaling up the production. Our systematic studies reveal that the starting reactant concentration and the reaction temperature, instead of the reaction time, have a great influence on the morphologies of the resulting alpha-Fe2O3. Several kinds of nanostructures, such as nanoparticles, dendritic crystals with different sizes, plates, and self-organized nanorods can be obtained under different conditions. Most importantly, this study provides a facile and high-yield pathway to crystalline self-organized hierarchical alpha-Fe2O3 nanoarchitectures without using any seed crystals, templates, or organic additives. Therefore, our protocol is promising for large-scale industrial production of high-quality complex alpha-Fe2O3 architectures. The products were characterized by using X-ray diffraction ( XRD), scanning electron microscopy ( SEM), transmission electron microscopy ( TEM), Raman spectroscopy, and X-ray photoelectron spectroscopy ( XPS).