Methanol-Sensing Property Improvement of Mesostructured Zinc Oxide Prepared by the Nanocasting Strategy

Journal of Nanomaterials, Feb 2013

The specific structure and morphology often play a critical role in governing the excellent intrinsic properties of the compound semiconductor. Herein, mesostructured ZnO with excellent methanol-sensing properties was prepared by a structure replication procedure through the incipient wetness technique. The investigation on the crystal structure and morphology of the resultant material shows that the product consists of hexagonally arranged mesopores and crystalline walls, and its structure is an ideal replication of CMK-3 template. Consequently, mesostructured ZnO was fabricated as a gas sensor for methanol. The excellent methanol-sensing performance was achieved at a relatively low operating temperature of 120°C. In comparison with the nonporous ZnO prepared through conventional coprecipitation approach, mesostructured ZnO material shows the higher sensitivity and stability. Furthermore, it shows the discrimination between methanol and ethanol sensitivity, which makes it a good candidate in fabricating selective methanol sensor in practice.

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Methanol-Sensing Property Improvement of Mesostructured Zinc Oxide Prepared by the Nanocasting Strategy

Methanol-Sensing Property Improvement of Mesostructured Zinc Oxide Prepared by the Nanocasting Strategy Qian Gao,1 Wei-Tao Zheng,1 Cun-Di Wei,1 and Hui-Ming Lin2 1College of Material Science and Engineering, Jilin University, Changchun 130022, China 2Key Laboratory of Semiconductor Nanocomposite Materials of Ministry of Education, College of Chemistry and Chemical Engineering, Harbin Normal University, Harbin 150025, China Received 20 December 2012; Accepted 9 January 2013 Academic Editor: Xiang Wu Copyright © 2013 Qian Gao 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. Abstract The specific structure and morphology often play a critical role in governing the excellent intrinsic properties of the compound semiconductor. Herein, mesostructured ZnO with excellent methanol-sensing properties was prepared by a structure replication procedure through the incipient wetness technique. The investigation on the crystal structure and morphology of the resultant material shows that the product consists of hexagonally arranged mesopores and crystalline walls, and its structure is an ideal replication of CMK-3 template. Consequently, mesostructured ZnO was fabricated as a gas sensor for methanol. The excellent methanol-sensing performance was achieved at a relatively low operating temperature of 120°C. In comparison with the nonporous ZnO prepared through conventional coprecipitation approach, mesostructured ZnO material shows the higher sensitivity and stability. Furthermore, it shows the discrimination between methanol and ethanol sensitivity, which makes it a good candidate in fabricating selective methanol sensor in practice. 1. Introduction Zinc oxide has been widely investigated because of the hopes it raises for a wide range of technological applications such as catalysts [1, 2], transparent conductors [3], field-emission devices [4], optoelectronic devices [5–7], and also for its fundamental scientific significance. However, besides its excellent intrinsic properties, the structure-activity relationship plays quite an important role in most of its numerous applications [8, 9]. As one important application, semiconducting zinc oxide is a promising material for sensing various gases [10–15]. Since semiconductor gas sensors are based on surface-chemical interaction between the gas molecules and the crystalline materials [14, 16]. With large surface-to-volume ratios and well-defined pore structures, mesostructured metal oxides are particularly desired for improving sensing performance [17–19]. As we known, it is difficult to prepare mesostructured metal oxides by directing soft-template method. The hard template method makes it possible to synthesize mesostructured metal oxides with excellent gas-sensing properties [20–22]. At present, many mesostructured metal oxides have been obtained by the utilization of nanoporous silica as matrices, including In2O3 [18, 23], Fe2O3 [24], Co3O4 [25, 26], and Cr2O3 [26]. However, it is impossible to get ZnO mesostructures by nanocasting of mesoporous silica, because ZnO is an amphoteric oxide, and its structure will be destroyed in both acidic and alkali solution during the removal of the hard template. Although mesoporous carbon instead of silica could be used as structure matrix, the hydrophobic character of the carbon template is incompatible with the aqueous precursor solution. For the difficulty in obtaining ZnO with highly ordered mesostructures, the synthesis of ordered mesoporous ZnO through nanocasting was not reported until 2007 [27]. For this reason, to the best of our knowledge, few investigations on the sensing properties of ordered mesoporous ZnO have been reported [28]. In this research, the methanol-sensing properties of ordered mesoporous ZnO were investigated. As we known, methanol is a kind of widely used organic solvent with a broad application in power sources and the manufacturing of dyes, drugs, perfumes, and so forth. However, it is highly toxic and is often fatal to humans [29]. Thus, it is imperative to develop highly selective sensor for the detection of methanol. Herein, we present the synthesis of ZnO with ordered mesostructure for methanol sensor. The methanol-sensing test reveals that the sensor fabricated from mesostructured zinc oxide exhibits high sensitivity and selectivity towards methanol at a relatively low working temperature of 120°C, which is much better than that of the corresponding nonporous materials synthesized by conventional approach. Furthermore, in contrast to the reported ZnO materials which are applied as ethanol sensors [10, 13, 30, 31], this mesostructured ZnO material with uniform mesoporous structure shows higher response to methanol than ethanol without doping any additive and promoter. The discrimination between methanol and ethanol sensiti (...truncated)


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Qian Gao, Wei-Tao Zheng, Cun-Di Wei, Hui-Ming Lin. Methanol-Sensing Property Improvement of Mesostructured Zinc Oxide Prepared by the Nanocasting Strategy, Journal of Nanomaterials, 2013, 2013, DOI: 10.1155/2013/263852