Abstract
In this study, we reported a successful synthesis of a nanocomposite based on SnO2 nanoneedles anchored to NiO microsphere by a simple two-step hydrothermal route. The results show that the SnO2/NiO nanocomposite-based sensor exhibits more prominent performances than the pristine NiO microsphere to NO2 such as larger responses and more outstanding repeatability. The improved properties are mainly attributed to the p–n heterojunctions formed at the SnO2–NiO interface, leading to the change of potential barrier height and the enlargement of the depletion layer. Besides, the novel and unique nanostructure provides large and effective areas for the surface reaction. In addition, a plausible growth mechanism and the enhanced sensing mechanism were proposed to further discuss the special nanostructure which will benefit the exploration of high-performance sensors.
Highlights
Metal-oxide semiconductor sensor, which plays an important role among the most necessary devices in our everyday life, has been extensively applied in various areas of gas analysis such as the identification of hazardous gases, the monitoring of air quality and the detection of environmental pollution [1,2,3,4,5]
Sun and his co-authors reported a facile hydrothermal synthesis of TiO2 nanorods decorated with NiO nanopartieles, and the sensor based on the materials showed ultrahigh sensitivity towards 200 ppm acetone in comparison to that of the pure NiO [26]
To confirm the synthesis of the composite, it is obvious from another result that the diffraction peaks around 26.7◦, 33.9◦, 52.6◦, and 62.0◦ could be indexed to (110), (101), (211), and (002) planes of the SnO2 (JCPDS 41-1445), verifying the coexistence of SnO2 and NiO
Summary
Metal-oxide semiconductor sensor, which plays an important role among the most necessary devices in our everyday life, has been extensively applied in various areas of gas analysis such as the identification of hazardous gases, the monitoring of air quality and the detection of environmental pollution [1,2,3,4,5]. Traditional pristine NiO-based sensors have limited gas-sensing performances such as high working temperature, low sensitivity and unsatisfactory repeatability, which may impose restrictions on the fabrication of high-performance sensors [18]. In this regard, considerable efforts have been devoted to breaking through this limitation like morphology control [19,20], metal doping [21,22], nanocompositing [23,24] and so on. Zhu et al synthesized hierarchical NiO/ZnO nanoflower, and the ethanol sensor based on the nanocomposite presented large gas responses and prominent repeatability due to the formation of the p–n heterojunction [27]
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