NegativelyDoped SingleWalled Carbon Nanotubes Decorated with Carbon Dots for Highly Selective NO2 Detection
- NegativelyDoped SingleWalled Carbon Nanotubes Decorated with Carbon Dots for Highly Selective NO2 Detection
- 변영태; 임남수; 이재성
- Carbon dots; singlewalled carbon nanotubes; nitrogen dioxide; gas sensor
- Issue Date
- VOL 10-2509-11
- In this study, we demonstrated a highly selective chemiresistivetype NO2 gas sensorusing facilely prepared carbon dot (CD)decorated singlewalled carbon nanotubes (SWCNTs). TheCDdecorated SWCNT suspension was characterized using transmission electron microscopy(TEM), Xray diffraction (XRD), and UVvisible spectroscopy, and then spread onto an SiO2/Sisubstrate by a simple and costeffective sprayprinting method. Interestingly, the resistance of oursensor increased upon exposure to NO2 gas, which was contrary to findings previously reported forSWCNTbased NO2 gas sensors. This is because SWCNTs are strongly doped by the electronrichCDs to change the polarity from ptype to ntype. In addition, the CDs to SWCNTs ratio in the activesuspension was critical in determining the response values of gas sensors; here, the 2:1 deviceshowed the highest value of 42.0% in a sensing test using 4.5 ppm NO2 gas. Furthermore, the sensorselectively responded to NO2 gas (response ~15%), and to other gases very faintly (NO, response~1%) or not at all (CO, C6H6, and C7H8). We propose a reasonable mechanism of the CDdecoratedSWCNTbased sensor for NO2 sensing, and expect that our results can be combined with those ofother researches to improve various device performances, as well as for NO2 sensor applications.
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