纳米棒
热液循环
煅烧
单斜晶系
三氧化钨
材料科学
水热合成
化学工程
三氧化钼
钨
纳米技术
晶体结构
钼
结晶学
化学
催化作用
有机化学
冶金
工程类
作者
Shouli Bai,Kewei Zhang,Ruixian Luo,Dianqing Li,Chung Chiun Liu
摘要
Tungsten trioxide (WO3) nanorods with an aspect ratio of ∼50 have been successfully synthesized by hydrothermal reaction at a low temperature of 100 °C. The crystal structure, morphology evolution and thermal stability of the products are characterized in detail by XRD, FESEM, FTIR, and TG/DTA techniques. The diameter evolution and distribution of WO3 nanorods strongly depend on hydrothermal temperature and time. Hydrothermal conditions of 100 °C and 24 h ensure the formation of well-defined WO3 nanorods. The transition of the crystal structure from monoclinic WO3 to hexagonal WO3 occurs after calcination at 400 °C. The appropriate calcination conditions of the WO3 nanorods are defined to be 600 °C and 4 h for gas-sensing applications. Response measurements reveal that the WO3 sensor operating at 200 °C exhibits high sensitivity to ppm-level NO2 and small cross-sensing to CO and CH4, which makes this kind of sensor a competitive candidate for NO2-sensing applications. Moreover, impedance measurements indicate that a conductivity mechanism of the sensor is mainly dependent on the grain boundaries of WO3 nanorods. A possible adsorption and reaction model is proposed to illustrate the gas-sensing mechanism.
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