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

Mesoporous α-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 α-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 α-Fe2O3, which is driven by surface anisotropy. Superparamagnetic behavior of mesoporous α-Fe2O3 is also associated with surface spins with blocking temperature around 50 K. When applied as gas sensors, mesoporous α-Fe2O3 nanostructures exhibited high gas sensitivity toward acetic acid and ethanol gas. As anodes in lithium ion cells, mesoporous α-Fe2O3 materials show a high specific capacity of 1360 mAh/g with excellent cycling stability and high rate capacity.