Anomalous gas sensing behaviors to reducing agents of hydrothermally grown alpha-Fe2O3 nanorods

Year: 2018

Authors: Donarelli M., Milan R., Rigoni F., Drera G., Sangaletti L., Ponzoni A., Baratto C., Sberveglieri G., Comini E.

Autors Affiliation: SENSOR Lab., Department of Information Engineering, University of Brescia, Via Branze 38, 25123, Brescia, Italy; National Institute of Optics, National Research Council (CNR-INO), Unit of Brescia, Via Branze 45, 25123, Brescia, Italy; Division of Materials Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, SE-971 87, Luleå, Sweden; Department of Mathematics and Physics, Catholic University of Sacred Heart, Via dei Musei 41, 25121, Brescia, Italy; NASYS srl, Via Branze 38, 25123, Brescia, Italy

Abstract: alpha-Fe2O3 nanorods have been grown by hydrothermal method, dispersed in ethanol and drop casted on a pre patterned alumina substrate with Pt electrodes. Their morphology, crystalline and electronic properties have been investigated by Scanning Electron Microscopy, Raman and X-ray Photoelectron Spectroscopies and X-ray Diffraction. The so-fabricated devices have been used for hydrogen gas sensing, showing their ability to detect H-2 at operating temperatures > 200 degrees C, at relative humidity values comprised from 0% to 50%. The sensing behavior of alpha-Fe2O3 nanorods is compatible with an n to p conductivity transition when the operating temperature is increased up to 300 degrees C. Outstanding p-type hydrogen sensing performances of alpha-Fe2O3 have been observed and reported. Besides H-2 detection, the alpha-Fe2O3 nanorods-based device is a good humidity sensor, at room temperature (n-type) and at 400 degrees C (p-type). CO and ethanol sensing performances have been investigated at different operating temperatures and relative humidity values. CO and ethanol anomalous acceptor-like behaviors at 200 degrees C in humid air has been explained by the interactions of these target gases with the water molecules adsorbed on the metal oxide surfaces.


Volume: 273      Pages from: 1237  to: 1245

KeyWords: Hematite; n-p transition; Hydrothermal; Hydrogen sensing;
DOI: 10.1016/j.snb.2018.07.042

Citations: 12
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