The selective detection of C2H5OH using SnO2–ZnO thin film gas sensors prepared by combinatorial solution deposition

Sensing materials for selective detection of C2H5OH were designed using combinatorial solution deposition of SnO2–ZnO thin films. The SnO2–ZnO composite sensor prepared by alternate deposition of 10 droplets of SnO2 and ZnO sols (S50Z50 sensor) showed a high response to 200 ppm C2H5OH (S(ethanol) = Ra/Rg = 4.69, Ra: resistance in air, Rg: resistance in gas) at 300 °C, while the gas responses to 100 ppm C3H8, 100 ppm CO, 200 ppm H2, and 5 ppm NO2 ranged from 1.11 to 1.19. The S(ethanol) value of the S50Z50 sensor was twice that to 200 ppm CH3COCH3 (S(acetone)). In contrast, the S(ethanol) and S(acetone) of pure SnO2 and ZnO thin films were similar to each other. The heterostructure between SnO2 and ZnO was suggested as one of the probable reasons for the successful discrimination between C2H5OH and CH3COCH3.