Controlled synthesis of hierarchical Sn-doped α-Fe2O3 with novel sheaf-like architectures and their gas sensing properties

Abstract

Monodisperse Sn-doped α-Fe₂O₃ with novel wheat sheaf-like hierarchical architectures were synthesized by a facile one-step hydrothermal method. Field emission scanning electron microscopy and transmission electron microscopy images revealed that these sheaf-like microstructures were built from filamentary crystals-stacked nanoparticles. The high resolution transmission electron microscopy image from a single “filament” showed that all the nanoparticles were highly oriented. The morphology and size of products could be controlled by simply adjusting the concentration of Sn⁴⁺. A possible formation mechanism involving oriented aggregation and Ostwald ripening was proposed on the basis of the results of time-dependent experiments. To demonstrate the usage of such α-Fe₂O₃ hierarchical architectures, the obtained sample was applied to fabricate a gas sensor which was then tested for response to three kinds of gases (ethanol, methanol, and formaldehyde). Results of that test showed that the sensor had high response, and rapid response kinetics to ethanol at the operating temperature of 250 °C.