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Sun Y.-F.,Anhui Polytechnic University | Sun Y.-F.,Chinese Academy of Sciences | Sun Y.-F.,Wuhu Returned Overseas Students Enterprise Park | Liu S.-B.,Wuhu Returned Overseas Students Enterprise Park | And 5 more authors.
Sensors | Year: 2012

Metal oxide gas sensors are predominant solid-state gas detecting devices for domestic, commercial and industrial applications, which have many advantages such as low cost, easy production, and compact size. However, the performance of such sensors is significantly influenced by the morphology and structure of sensing materials, resulting in a great obstacle for gas sensors based on bulk materials or dense films to achieve highly-sensitive properties. Lots of metal oxide nanostructures have been developed to improve the gas sensing properties such as sensitivity, selectivity, response speed, and so on. Here, we provide a brief overview of metal oxide nanostructures and their gas sensing properties from the aspects of particle size, morphology and doping. When the particle size of metal oxide is close to or less than double thickness of the space-charge layer, the sensitivity of the sensor will increase remarkably, which would be called "small size effect", yet small size of metal oxide nanoparticles will be compactly sintered together during the film coating process which is disadvantage for gas diffusion in them. In view of those reasons, nanostructures with many kinds of shapes such as porous nanotubes, porous nanospheres and so on have been investigated, that not only possessed large surface area and relatively mass reactive sites, but also formed relatively loose film structures which is an advantage for gas diffusion. Besides, doping is also an effective method to decrease particle size and improve gas sensing properties. Therefore, the gas sensing properties of metal oxide nanostructures assembled by nanoparticles are reviewed in this article. The effect of doping is also summarized and finally the perspectives of metal oxide gas sensor are given. © 2012 by the authors.

Sun Y.-F.,Anhui Polytechnic University | Sun Y.-F.,Hefei University of Technology | Sun Y.-F.,Wuhu Returned Overseas Students Enterprise Park | Sun Y.-F.,Chinese Academy of Sciences | And 7 more authors.
Gongneng Cailiao/Journal of Functional Materials | Year: 2012

Graphene have attracted wide attention for its unique characteristics (e. g. electronic, thermal, mechanical etc.). Graphene oxide not only possesses the intrinsic properties of graphene but also contains many oxygen-containing functional groups such as hydroxyl, epoxy, carboxyl and carbonyl groups. Those oxygen-containing functional groups may improve the adsorbability of graphene oxide to gases which is advantageous for its gas sensing properties. In this investigation, graphene oxide was synthesized by a modified Hummer's method. The gas sensing properties of the as-prepared graphene oxide to NH 3was then investigated. The results indicate that graphene oxide exhibited excellent sensitivities to NH 3 with a well linearly relationship ranging from 1.5×10 -4 to 3.5×10 -4.

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