Anodized nanoporous WO3 Schottky contact structures for hydrogen and ethanol sensing

Rosmalini Ab Kadir; Wei Zhang; Yichao Wang; Jian Zhen Ou; Wojtek Wlodarski; Anthony P. O'Mullane; Gary Bryant; Matthew Taylor; Kourosh Kalantar-zadeh

doi:10.1039/C4TA06286H

Anodized nanoporous WO₃ Schottky contact structures for hydrogen and ethanol sensing†

Rosmalini Ab Kadir,*^a Wei Zhang,^a Yichao Wang,^a Jian Zhen Ou,^a Wojtek Wlodarski,^a Anthony P. O'Mullane,^b Gary Bryant,^c Matthew Taylor^c and Kourosh Kalantar-zadeh*^a

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* Corresponding authors

^a School of Electrical and Computer Engineering, RMIT University, Melbourne, Victoria 3001, Australia
E-mail: rosmalini@gmail.com, kourosh.kalantar@rmit.edu.au

^b School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, Queensland 4001, Australia

^c Centre for Molecular and Nanoscale Physics, School of Applied Sciences, RMIT University, Melbourne, Victoria 3001, Australia

Abstract

This paper reports the development of nanoporous tungsten trioxide (WO₃) Schottky diode-based gas sensors. Nanoporous WO₃ films were prepared by anodic oxidation of tungsten foil in ethylene glycol mixed with ammonium fluoride and a small amount of water. Anodization resulted in highly ordered WO₃ films with a large surface-to-volume ratio. Utilizing these nanoporous structures, Schottky diode-based gas sensors were developed by depositing a platinum (Pt) catalytic contact and tested towards hydrogen gas and ethanol vapour. Analysis of the current–voltage characteristics and dynamic responses of the sensors indicated that these devices exhibited a larger voltage shift in the presence of hydrogen gas compared to ethanol vapour at an optimum operating temperature of 200 °C. The gas sensing mechanism was discussed, associating the response to the intercalating H⁺ species that are generated as a result of hydrogen and ethanol molecule breakdowns onto the Pt/WO₃ contact and their spill over into nanoporous WO₃.

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Article information

DOI: https://doi.org/10.1039/C4TA06286H
Article type: Paper
Submitted: 19 Nov 2014
Accepted: 01 Mar 2015
First published: 04 Mar 2015

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J. Mater. Chem. A, 2015,3, 7994-8001

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Anodized nanoporous WO₃ Schottky contact structures for hydrogen and ethanol sensing

R. Ab Kadir, W. Zhang, Y. Wang, J. Z. Ou, W. Wlodarski, A. P. O'Mullane, G. Bryant, M. Taylor and K. Kalantar-zadeh, J. Mater. Chem. A, 2015, 3, 7994 DOI: 10.1039/C4TA06286H

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Journal of Materials Chemistry A