Colloidal quantum dot-based surface acoustic wave sensors for NO2-sensing behavior

Li, Min, Kan, Hao, Chen, Shutian, Feng, Xiaoying, Li, Hui, Li, Chong, Fu, Chen, Quan, Aojie, Sun, Huibin, Luo, Jingting, Liu, Xueli, Wang, Wen, Liu, Huan, Wei, Qiuping and Fu, Yong Qing (2019) Colloidal quantum dot-based surface acoustic wave sensors for NO2-sensing behavior. Sensors and Actuators B: Chemical, 287. pp. 241-249. ISSN 0925-4005

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Abstract

Surface acoustic wave (SAW) sensors have great advantages in real-time and in-situ gas detection due to their wireless and passive characteristics. Using nanostructured sensing materials to enhance the SAW sensor’s responses has become a research focus in recent years. In this paper, solution-processed PbS colloidal quantum dots (CQDs) were integrated into quartz SAW devices for enhancing the performance of NO2 detection operated at room temperature. The PbS CQDs were directly spin-coated onto ST-cut quartz SAW delay lines, followed by a ligand exchange treatment using Pb(NO3)2. Upon exposure to 10 ppm of NO2 gas, the sensor coated with untreated PbS CQDs showed response and recovery times of 487 s and 302 s, and a negative frequency shift of -2.2 kHz, mainly due to the mass loading effect caused by the absorption of NO2 gas on the surface of the dense CQD film. Whereas the Pb(NO3)2-treated sensor showed fast response and recovery times of 45 s and 58 s, and a large positive frequency shift of 9.8 kHz, which might be attributed to the trapping of NO2 molecules in the porous structure and thus making the film stiffer. Moreover, the Pb(NO3)2-treated sensor showed good stability and selectivity at room temperature.

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