Selective CO gas detection of CuO- and ZnO-doped SnO2 gas sensor

CuO (1-10 mol%) and ZnO (3 mol%) were independently or simultaneously added to SnO2 to change the selectivity between CO and H gases of pellet-type SnO2 sensor. The effects of the additives on the electrical conductivity and thus the sensitivity to 200 ppm CO and 200 ppm 1-12 gases were examined in the temperature range from 80 to 450 degreesC. The electrical conductivity of SnO2 was drastically decreased by the addition of either CuO or ZnO. CuO addition to SnO2 lowered the temperature showing the maximum sensitivity value for either CO or H-2 gases. On the other hand. ZnO addition made SnO2 to be more sensitive to H-2 gas at higher temperatures. Consequently, SnO2 sensor reserved.