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Journal of Nanomaterials
Volume 2015 (2015), Article ID 820509, 8 pages
Research Article

Effects of Niobium-Loading on Sulfur Dioxide Gas-Sensing Characteristics of Hydrothermally Prepared Tungsten Oxide Thick Film

1Program in Materials Science, Faculty of Science, Maejo University, Chiang Mai 50290, Thailand
2National Electronics and Computer Technology Center, National Science and Technology Development Agency, Pathum Thani 12120, Thailand
3Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand

Received 7 August 2014; Revised 4 November 2014; Accepted 11 November 2014

Academic Editor: Rupesh S. Devan

Copyright © 2015 Viruntachar Kruefu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Nb-loaded hexagonal WO3 nanorods with 0–1.0 wt% loading levels were successfully synthesized by a simple hydrothermal and impregnation process and characterized for SO2 sensing. Nb-loaded WO3 sensing films were produced by spin coating on alumina substrate with interdigitated gold electrodes and annealed at 450°C for 3 h in air. Structural characterization by X-ray diffraction, high-resolution transmission electron microscopy, and Brunauer-Emmett-Teller analysis showed that spherical, oval, and rod-like Nb nanoparticles with 5–15 nm mean diameter were uniformly dispersed on hexagonal WO3 nanorods with 50–250 nm diameter and 100 nm–5 µm length. It was found that the optimal Nb loading level of 0.5 wt% provides substantial enhancement of SO2 response but the response became deteriorated at lower and higher loading levels. The 0.50 wt% Nb-loaded WO3 nanorod sensing film exhibits the best SO2 sensing performances with a high sensor response of ~10 and a short response time of ~6 seconds to 500 ppm of SO2 at a relatively low optimal operating temperature of 250°C. Therefore, Nb loading is an effective mean to improve the SO2 gas-sensing performances of hydrothermally prepared WO3 nanorods.