NiO thin-film formaldehyde gas sensor

The suitability of both pure and Li-doped NiO as a thin-film resistive gas sensor for formaldehyde has been investigated. Pure NiO had a linear formaldehyde sensitivity of 0.825 mV ppm−1 while that for 0.5 at.% Li-doped NiO was 0.488 mV ppm−1 at 600°C. These gas-sensing materials also showed similar sensitivity for methanol and acetone as well as a reduced sensitivity for toluene and ethanol. Chloroform was a poison for these gas-sensing materials. Due to resistive noise, the detection limit for formaldehyde was found to be ≈40 ppm.