基于电纺丝法的In2O3/CdO复合材料的制备及甲醛气敏特性

用静电纺丝法制备了In(NO₃)₃/聚乙烯吡咯烷酮(PVP)纺丝前驱物, 然后分别在500、600、700℃时烧结得到三种In₂O₃ 纳米纤维. 通过X 射线衍射(XRD)仪、热重差热分析(TG/DTA)、场发射扫描式电子显微镜(FE-SEM)表征结果得知, 500℃时In₂O₃的晶相已经形成, 且粒径为最小, 约为24 nm, 纳米纤维呈介孔结构.将三种烧结温度的In₂O₃纤维制作成气敏元件, 测试对比了三种元件对甲醛气体的敏感特性, 结果表明, 500℃烧结得到的In₂O₃纳米纤维在工作温度为240℃时响应最好, 对浓度为10×10^-6 (体积分数, φ)甲醛的响应为7.用静电纺丝法合成了CdO 纳米颗粒, 通过XRD、SEM 表征得知CdO 呈粒径约为68 nm 的颗粒. 将In₂O₃和CdO以不同摩尔比(1:1, 10:1, 20:1)复合, 对比测试了纯In₂O₃及三种In₂O₃/CdO复合材料对应的气敏元件对甲醛的气敏特性, 测试结果表明当In₂O₃纳米纤维与CdO纳米颗粒以摩尔比10:1 复合时, 元件的工作温度较低(200℃), 且对甲醛表现出最佳的气敏特性, 对浓度为10×10^-6甲醛的响应为13.6, 响应/恢复时间为140 s/32s. 最后对不同摩尔比复合的In₂O₃/CdO对甲醛的气敏机理进行了初步分析.

Preparation of Electrospun In2O3/CdO Composite and Its Formaldehyde-Sensing Properties

In(NO₃)₃/polyvinyl pyrrolidone (PVP) nanofiber precursors were synthesized using a traditional electrospinning method, and were then annealed at 500, 600, and 700℃ to form In₂O₃ nanofibers. The as-prepared In₂O₃ nanofibers were characterized using X-ray diffraction (XRD), thermal gravimetry and differential thermal analysis (TG/DTA), and field-emission scanning electron microscopy (FE-SEM). The results show that the In₂O₃ nanofibers crystallize well, with a small average grain size (about 24 nm) and a good mesoporous structure, when annealed at 500℃. The In₂O₃ nanofibers annealed at the three temperatures were further used to fabricate gas sensors. The test results show that the sensor based on In₂O₃ annealed at 500℃ has the highest response (about 7) to 10×10^-6 (volume fraction, φ) formaldehyde (HCHO) at an operating temperature of 240℃. CdO nanoparticles were also prepared using the same method; XRD and FE-SEM show that the average grain size of CdO is about 68 nm. Finally, the as-prepared In₂O₃ nanofibers were mixed with the as-prepared CdO in molar ratios of 1:1, 10:1, and 20:1, and the mixtures were used to fabricate gas sensors. The HCHO-sensing properties of the sensors based on pure In₂O₃ and In₂O₃/CdO composites with different molar ratios were investigated at each optimum temperature. The results show that the In₂O₃/CdO composite with a molar ratio of 10:1 has excellent sensing properties: the response to 10×10^-6 HCHO is 13.6, the response/recovery time is 140 s/32 s, and the selectivity is better at a lower operating temperature of 200 °C. In addition, the HCHO-sensing mechanism of the sensors based on the In₂O₃/CdO composites was briefly analyzed.