Room temperature gas sensor based on porous NiO nanoplates modified with rGO nanosheets and SnO2 nanoparticles for accurate and rapid ppb-level NO2 detection
Haineng Bai, Cheng Feng, Yiru Chen, Yunxiao Du, Yamin Feng, Kuili Liu, Yali Yan, Jia Liu, Baohua Zhang, Jin Wang, Dunjun Chen, Youdou Zheng, Fuqiang Guo
Abstract
The porous NiO nanoplates modified with rGO nanosheets and SnO 2 nanoparticles are developed for accurate and rapid ppb-level NO 2 detection. The developed SnO 2 /NiO/rGO sensor towards 50 ppm NO 2 gas demonstrates an excellent gas-sensing response of 14.8 at 23 °C, which is 3.03 times that of NiO/rGO sensor (4.89) and 6.49 times that of NiO sensor (2.28), respectively. The developed SnO 2 /NiO/rGO sensor exhibits faster response/recovery speed (12.7/32.8 s @5 ppm), with extra-low theoretical detection limit of 0.15 ppb at room temperature. More fascinatingly, our sensors indicate great sensitivity, outstanding repeatability and long-term stability for longer than 7 weeks. Additionally, it also suggests that 1 °C and 1 % relative humidity have the same effect on the SnO 2 /NiO/rGO sensor signal as approximately 13 ppb and 7.0 ppb NO 2 gas change, respectively. Such excellent properties are mainly attributed to the large surface-to-volume ratio, which provides active sites to NO 2 gas spread, adsorption and diffusion on material surface in redox reaction. Moreover, the ternary heterojunctions formed by NiO, rGO and SnO 2 may serve as highly conductive channels to accelerate carrier transfer and abundant oxygen vacancies to reduce the adsorption energy for O 2 and NO 2 gas, thus further improving performance of the sensors.