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Journal of Nanomaterials
Volume 2013 (2013), Article ID 136145, 9 pages
Research Article

Synthesis of Nanosized Zinc-Doped Cobalt Oxyhydroxide Parties by a Dropping Method and Their Carbon Monoxide Gas Sensing Properties

Department of Safety Health and Environmental Engineering, Chung Hwa University of Medical Technology, Tainan 717, Taiwan

Received 22 August 2012; Revised 21 December 2012; Accepted 23 December 2012

Academic Editor: Jinquan Wei

Copyright © 2013 Jian-Wen Wang and Yi-Ming Kuo. 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.


Two nanostructures of cobalt oxyhydroxide (CoOOH) and Zinc-(Zn-) doped CoOOH (1–4% Zn) are prepared from Co(NO3)2 solution via microtitration with NaOH and oxidation in air. The X-ray diffraction (XRD) analysis results show that a pure state of nano-CoOOH can be obtained at an alkalinity (OH/Co+) of 5 with 40°C heat treatment after 6 h. The Zn ions preferentially substitute Co ions in the CoOOH structure, resulting in a decrease of its crystallinity. The disc-like CoOOH nanostructure exhibits good sensitivity to carbon monoxide (CO) in a temperature range of 40–110°C with maximum sensitivity to CO at around 70–80°C. When CoOOH nanostructure is doped with 1% Zn, its sensitivity and selectivity for CO gas are improved at 70–80°C; further Zn doping to 2% degraded the CO sensing properties of nano-CoOOH. The results of a cross-sensitivity investigation of the sensor to various gases coexisting at early stages of a fire show that the sensitivity of Zn-doped nano-CoOOH is the highest toward CO. Zn-doped nano-CoOOH film exhibits a high sensitivity to CO at room temperature, making it a promising sensor for early-stage fire detection.