Trimethylamine sensing properties of nano-SnO_2 prepared using microwave heating method

摘要

The precursor was obtained through the reaction between SnCl_4 5H_2O and NaOH in the presence of PEG400 (polyethylene glycol, M = 400). Tin oxide (SnO_2) nano-powders were prepared by heating the precursor with microwave method. SnO_2 thick film sensors were fabricated using SnO_2 nano-materials as sensing materials. The phase composition and morphology of the material particles were characterized through X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The average particle sizes of the samples obtained with 616 W microwave heating and 800 Wmicrowave heating (20 min) are about 5 and 15 nm, respectively. The influence of the heating duration and heating power on the gas-sensing properties of sensors based on SnO2 nano-materials were investigated. The sensitivities of the sensors based on SnO_2 nano-materials heated with 616 and 800 W for 20 min were higher than those of the sensors based on SnO_2 nano-materials heated with 136, 264 and 440 Wfor 20 min. When operating at 200–310℃, the sensor based on SnO_2 heated with 616 Wfor 20 min exhibits highest sensitivities in all sensors based on SnO_2 heated with 616 W for different duration. The sensitivity to a few kinds of organic gases, such as (CH_3)_3N and (CH_3)_2CO were studied. It was found that the sensor based on SnO_2 nano-materials (with 616 Wmicrowave heating for 20 min) exhibited good performance characterized by high sensitivity and short response time to dilute trimethylamine when operated at 255℃. The sensitivity to 0.001 ppm (CH_3)_3N at 255℃ was 3. The response time and recovery time were about 30 and 100 s, respectively.