C2H5OH and LPG sensing properties of α-Fe2O3 microflowers prepared by hydrothermal route

Abstract

The flower-like micron-structure of α-Fe₂O₃ was synthesized via hydrothermal treatment at 140 °C for 24 h using Fe(NO₃)₃.9H₂O and Na₂SO₄ as the precursors. A thin film constructed by the as-prepared material was created by spin coating technique. The structure, morphology, and composition of the samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM). The α-Fe₂O₃ microflowers (MFs) with average diameter of several micrometers are assembled of nanorods which possess average diameter and length of 40 nm and hundred nm, respectively. The gas sensing properties of α-Fe₂O₃ film were tested with ethanol (C₂H₅OH) and liquefied petroleum gas (LPG) at the operating temperatures of 225–400 °C. The sensor response of the α-Fe₂O₃ film reached highest sensitivity to C₂H₅OH and LPG at 275 °C and 350 °C, respectively. The thin film exhibited higher sensitivity and lower working temperature to C₂H₅OH than those to LPG. The film can detect minimum concentration of 250 ppm C₂H₅OH. The response time of the film to C₂H₅OH is approximately 30 s.