Synthesis of Mesoporous α-Fe2O3 Nanostructures for Highly Sensitive Gas Sensors and High Capacity Anode Materials in Lithium Ion Batteries

Mesoporous alpha-Fe2O3 materials were prepared in large quantity by the soft template synthesis method using the triblock copolymer surfactant F127 as the template. Nitrogen adsorption desorption isothermal measurements and transmission electron microscope observation revealed that the as-prepared mesoporous alpha-Fe2O3 nanostructures have large mesopores in a wide size range of 5-30 nm. It has been found that the Morin transition depends on thermal history of mesoporous alpha-Fe2O3, which is driven by surface anisotropy. Superparamagnetic behavior of mesoporous alpha-Fe2O3 is also associated with surface spins with blocking temperature around 50 K. When applied as gas sensors, mesoporous alpha-Fe2O3 nanostructures exhibited high gas sensitivity toward acetic acid and ethanol gas. As anodes in lithium ion cells, mesoporous alpha-Fe2O3 materials show a high specific capacity of 1360 mAh/g with excellent cycling stability and high rate capacity.