Microwave-assisted synthesis and humidity sensing of nanostructured α-Fe2O3

Nanocrystalline α-Fe2O3 has been prepared on a large-scale by a facile microwave-assisted hydrothermal route from a solution of Fe(NO3)3·9H2O and pentaerythritol. A systematic study of the morphology, crystallinity and oxidation state of Fe using different characterization techniques, such as transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy was performed. It reveals that nanostructured α-Fe2O3 comprises bundles of nanorods with a rhombohedral crystalline structure. The individual nanorod has 8–10 nm diameter and ∼50 nm length. The as-prepared nanostructured α-Fe2O3 (sensor) gives selective response towards humidity. The sensor shows high sensitivity, fast linear response to change in the humidity with almost 100% reproducibility. The sensor works at room temperature and rejuvenates without heat treatment. The as-prepared nanostructured α-Fe2O3 appears to be a promising humidity sensing material with the potential for commercialization.