NO2 sensing studies of WO3 and Ag doped WO3 prepared through sol-gel route

Paper reports sensing studies of NO
2
gas by WO
3
(prepared through sol-gel route) and Ag doped WO
3
for operating temperatures 200°C, 250°C and 300°C, for NO
2
gas concentration of 0 to 100 ppm. Both pure WO
3
and Ag doped WO
3
show better sensitivity for the operating temperature of 200°C. WO
3
and Ag doped WO
3
both show increase in value of sensitivity with increasing concentration (ppm) of NO
2
. For concentration of 100 ppm, sensitivity for sensing element of Ag doped WO
3
over WO
3
increased by 25% for operating temperature 200°C. Response time of sensors depend on operating temperatures both for pure WO
3
and Ag doped WO
3
. Least response time was obtained for operating temperature of 200°C.