Low temperature solution-based synthesis of porous flower-like α-Fe₂O₃ superstructures and their excellent gas-sensing properties

A facile solution approach was employed to synthesize flower-like α-FeOOH precursors by using FeSO₄·7H₂O and CO(NH₂)₂ as raw materials at 80 °C for 6 h without any template and surfactant. After annealing in air at 500 °C for 2 h, the porous flower-like α-Fe₂O₃ superstructures were successfully obtained, whose morphological feature is characterized as self-assembled by porous nanorods with an average length of 0.1-1.0 μm and diameter of 50-150 nm. Transmission electron microscopy (TEM) images show that there are many porous walls with a pore size of about 10 nm on the surface. As a demonstration of potential application for gas-sensing materials, the porous flower-like superstructures exhibited short response/recovery time within 6/3 s, and presented a much higher gas response than α-Fe₂O ₃ nanoparticles aggregations towards different concentrations of ethanol, methanol and acetone.