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High-Response Room-Temperature NO₂ Sensor and Ultrafast Humidity Sensor Based on SnO₂ with Rich Oxygen Vacancy

Zhong, Yujia, Li, WeiWei, Zhao, Xuanliang, Jiang, Xin, Lin, Shuyuan, Zhen, Zhen, Chen, Wenduo, Xie, Dan, Zhu, Hongwei
ACS applied materials & interfaces 2019 v.11 no.14 pp. 13441-13449
ambient temperature, annealing, carbon, humidity, nanosheets, nitrogen dioxide, oxygen, tin, tin dioxide, transmission electron microscopy
SnO₂ nanosheets with abundant vacancies (designated as SnO₂–ₓ) have been successfully prepared by annealing SnSe nanosheets in Argon. The transmission electron microscopy results of the prepared SnO₂ nanosheets indicated that high-density SnO₂–ₓ nanoplates with the size of 5–10 nm were distributed on the surface of amorphous carbon. After annealing, the acquired SnO₂–ₓ/amorphous carbon retained the square morphology. The stoichiometric ratio of Sn/O = 1:1.55 confirmed that oxygen vacancies were abundant in SnO₂ nanosheets. The prepared SnO₂–ₓ exhibited excellent performance of sensing NO₂ at room temperature. The response of the SnO₂–ₓ-based sensor to 5 ppm NO₂ was determined to be 16 with the response time and recovery time of 331 and 1057 s, respectively, which is superior to those of most reported room-temperature NO₂ sensors based on SnO₂ and other materials. When the humidity varied from 30 to 40%, ΔR/R was 0.025. The ultrafast humidity response (52 ms) and recovery (140 ms) are competitive compared with other state-of-art humidity sensors. According to the mechanistic study, the excellent sensing performance of SnO₂–ₓ is attributed to its special structure.