Highly sensitive and selective NO<inf>2</inf> sensor based on Au-impregnated WO<inf>3</inf> nanorods

• Main Authors: Kabcum S., Kotchasak N., Channei D., Tuantranont A., Wisitsoraat A., Phanichphant S., Liewhiran C.
• Format: Journal
• Published: 2017
• Online Access: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85020677407&origin=inward; http://cmuir.cmu.ac.th/jspui/handle/6653943832/41128
• Institution: Chiang Mai University

© 2017 Elsevier B.V. In this work, Au-impregnated WO 3 nanorods with high-aspect-ratio were synthesized by a modified precipitation/impregnation method and systematically investigated for NO 2 detection. Characterizations by electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy revealed the formation of 5–20 nm spherical and oval Au nanoparticles loaded on the surface of polycrystalline WO 3 nanorods. WO 3 sensing films with varying Au loading levels from 0 to 2 wt% fabricated by powder pasting and spin coating were tested towards NO 2 over operating temperatures ranging from 25 to 350 °C. It was found that an optimal Au loading of 0.5 wt% led to significant enhancement of NO 2 -sensing performances. In particular, the optimal Au-loaded WO 3 sensing film exhibited the highest response of 836.6 with response time of 64.2 s to 5 ppm NO 2 at the optimal operating temperature of 250 °C. Moreover, the sensor displayed high NO 2 selectivity against NO, N 2 O, C 2 H 5 OH, CO, NH 3 , SO 2 and H 2 . The observed enhancement could be attributed to the formation of metal-semiconductor ohmic junctions and electronic sensitization effects of Au nanoparticles on the porous network of WO 3 nanorods. Therefore, the Au-impregnated WO 3 nanorods are highly potential for sensitive and selective NO 2 detection.