Study on sensing mechanism of CuO–SnO2 gas sensors

The preparations of SnO2 and CuO powders and the manufacture of CuO–SnO2 gas sensors are described in some details. The CuO content was chosen as 1.5 mol.% (sample 1), 4.4 mol.% (sample 2), 8.4 mol.% (sample 3) and 12.5 mol.% (sample 4), respectively. The resistance of all samples in air and their sensitive properties to H2S, alcohol vapor, C4H10 and CH2 were measured in the temperature range 20–300 °C, respectively. The results show that the resistance of all samples decreases exponentially with increasing temperature, when the temperature is >31 °C and it increases with an increase in CuO content at a given temperature. Sample 3 exhibits the best sensitive property in the case of the same H2S–air mixture concentration and excellent selectivity. The sensitive mechanisms of these samples to different gases are discussed in details.