Controlled synthesis of various Fe2O3 morphologies as energy storage materials.

Air pollution from vehicle emissions is a major problem in developing countries. Consequently, the use of iron-based rechargeable batteries, which is an effective method of reducing air pollution, have been extensively studied for electric vehicles. The structures and morphologies of iron particles significantly affect the cycle performance of iron-based rechargeable batteries. The synthesis parameters for these iron materials also remarkably influence their structures, shapes, sizes, and electrochemical properties. In this study, we fabricated α-Fe2O3 materials with various shapes and sizes via a facile hydrothermal route and investigated the effects of raw materials on their structures, morphologies, and properties. The structural characteristics of the synthesized iron oxides were studied via X-ray diffraction using scanning electron microscopy. Results indicate that changing the concentration of raw materials modified the structure and morphology of the synthesized α-Fe2O3 particles, that is, the desired shape and size of α-Fe2O3 can be controlled. The effects of the structure and morphology of α-Fe2O3 particles on their electrochemical characteristics were investigated. The results show that the morphology and shape of the iron oxide particles remarkably affected the redox reaction rate and discharge capacity of the Fe2O3/C composite electrodes. Among the synthesized α-Fe2O3 materials, the cubic-shaped α-Fe2O3 exhibited the highest discharge capacity. This material is a potential candidate for application in iron-based aqueous batteries. Our results may facilitate not only the controlled synthesis of α-Fe2O3 nanoparticles for potential technical applications but also the production of electrode materials with high capacity and good cycle performance for iron-based rechargeable batteries.