Fig. 3a shows the comparison of response of ZnO for 1000 ppm of CO and 250 ppm of ethanol as well as acetaldehyde at different testing temperatures.
The highest response for CO gas is 4.93 at 200 °C testing temperature.
The response increases from 100 to 200 °C and then sharply decreased at 300 °C while again increased at 400 °C.