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

Abstract CuO (1–10 mol%) and ZnO (3 mol%) were independently or simultaneously added to SnO 2 to change the selectivity between CO and H 2 gases of pellet-type SnO 2 sensor. The effects of the additives on the electrical conductivity and thus the sensitivity to 200 ppm CO and 200 ppm H 2 gases were examined in the temperature range from 80 to 450°C. The electrical conductivity of SnO 2 was drastically decreased by the addition of either CuO or ZnO. CuO addition to SnO 2 lowered the temperature showing the maximum sensitivity value for either CO or H 2 gases. On the other hand, ZnO addition made SnO 2 to be more sensitive to H 2 gas at higher temperatures. Consequently, SnO 2 sensor co-doped with ZnO and CuO showed a high selectivity to CO gas (S CO /S H 2 ∼5) at ∼160°C.