Highly sensitive ethanol sensors based on nanocrystalline SnO2 thin films

This paper reports on a simple and inexpensive ultrasonic spray pyrolysis method to synthesize agglomerate-free nanosized SnO2 particles with a size smaller than 10 nm. Scanning electron microscopy, transmission electron microscopy and high resolution X-ray diffraction studies were used to characterize the morphology, crystallinity, and structure of the SnO2 particles. Under the optimized experimental conditions, the prepared SnO2 sensor shows the high response (S = 491) towards 100 ppm ethanol gas at 300 °C, linearity in the range of 100–500 ppm, quick response time (2 s), recovery time (60 s) and selectivity against other gases. The response of the sensor was monitored in a 250–450 °C temperature range. The seven fold enhancement in gas response and selective detection of C2H5OH in the presence of other gases such as CH3OH and CH3CHOHCH3 are the significant points in this investigation. These results demonstrate that pure nanocrystalline SnO2 thin film can be used as the sensing material for fabricating high performance ethanol sensors.