Improved and excellent ethanol sensing properties of SnO2/multiwalled carbon nanotubes

Abstract

SnO 2 /multiwalled carbon nanotubes (MWNTs) have been studied as gas sensing materials. Compared with pure SnO 2 , SnO 2 /MWNTs exhibit improved ethanol sensing properties such as higher sensitivity and quicker response/recovery at 300°C. The sensitivity is 35, 65, 166 and 243 to 500, 1000, 2000 and 3000 ppm ethanol, respectively. The response time is about 1 s, and the recovery time is about 5 s. The sensing improvement is explained in terms of the appropriate basal resistance and enhanced signal transfer brought by MWNTs. metal oxide semiconductors, gas sensors, SnO 2 , multiwalled carbon nanotubes, ethanol Citation: Liu L, Zhuang J, Liu K X, et al. Improved and excellent ethanol sensing properties of SnO 2 /multiwalled carbon nanotubes.Metal oxide semiconductor-based gas sensors have attracted much focus owing to their tiny structure, low cost, and high compatibility with microelectronic processing [1]. Hitherto, the impressive and promising results regarding the synthesis, fabrication, chemical and physical properties of these metal oxide semiconductor sensing materials have been achieved [2][3][4]. The investigation of a good gas sensor is focused on the improvement of many requirements, including low basal resistance (resistance in air), high sensitivity, and quick response/recovery [5]. These properties are strongly dependent on the morphology and structure of materials, namely, grain size, surface area, dimension, as well as the type of grain network or porosity [6]. Thus extensive studies have been carried out on improving the sensing performance by adding catalysts, doping metals and metal oxides, decreasing grain size, controlling pore and surface defects, etc.[6].Recently, one-dimensional (1D) nanostructures have been proved to be promising sensing materials due to their high density of surface sites, increased surface-to-volume ratio (and hence are expected to be more sensitive), and the nanoscale size (likely to allow complete depletion from charge carriers) [7]. Researchers in the sensor field are nowadays oriented towards these kinds of nanostructures, in order to investigate the real capabilities of these novel 1D structures to improve the performance of bulk and thin/thick film chemical sensors [8]. Many 1D nanostructures such as ZnO nanobelts, TiO 2 nanofibers, SnO 2 nanorods, single-walled carbon nanotubes (SWNTs), and multiwalled carbon nanotubes (MWNTs) have been employed for sensing applications [8][9][10]. However, few papers on sensing performance of particle/1D nanostructure compounds have been explored. Additionally, the synthesis of high sensitive materials with quick response /recovery and low cost is still in great demand.Here, we report the ethanol sensing properties of SnO 2 /MWNTs. SnO 2 has been chosen in our experiment for its excellent sensing properties for the detection of both reducing and oxidizing gases [11,12]. On the other hand, MWNTs with high conductivity and large surface-to-volume

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