Highly sensitive and selective detection of ethanol vapor using flame-spray-made CeOx-doped SnO2 nanoparticulate thick films

- Flame-made SnO2 nanoparticles were incorporated with 0-1 wt% Ce.
- Structural analyses suggested that CeOx crystallites with mixed Ce4+ and Ce3+ states were soluted in SnO2 matrix.
- Response to 200 ppm ethanol at 350 °C was greatly enhanced from 25 to 2654 with 0.5 wt% Ce.
- The optimal sensor exhibited high ethanol selectivity against C3H6O, CH4, H2, NO2, H2S and H2O.
- The results were attributed to distributed n-n heterjunctions, strong CeOx catalytic activity and reduced structural sizes.

In the present work, flame-spray-made CeOx-doped SnO2 nanoparticles with 0.1-1 wt% Ce contents were systematically studied for ethanol detection. Structural characterizations by electron microscopy, Nitrogen adsorption and X-ray analysis indicated that SnO2 nanoparticles were highly crystalline with tetragonal structure and CeOx crystallites with mixed Ce3+ and Ce4+ oxidation states should form a solid solution with SnO2 matrix. The sensing films were tested towards 3-200 ppm ethanol at operating temperatures ranging from 200 to 400 °C in dry air. Gas-sensing results demonstrated that the SnO2 sensing film with the optimal Ce content of 0.5 wt% exhibited a very high response of ∼2654-200 ppm ethanol with a short response time of 1.1 s at the optimal operating temperature of 350 °C. Moreover, the optimal sensor displayed high ethanol selectivity against C3H6O, CH4, H2, NO2, H2S and H2O. Therefore, the flame-made CeOx-doped SnO2 sensor is a promising candidate as a sensitive and selective ethanol detector for drunk-driving and biomedical applications.

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