Photon assisted ultra-selective Formaldehyde sensing by defect induced NiO nanostructured sensing layer

Indoor air quality (IAQ) monitoring is quite essential to maintain healthy human life. Among different pollutants effecting IAQ, formaldehyde is one toxic VOC that needs to be monitored. In this work, hierarchical NiO nanostructured thin film devices are used as highly selective and sensitive formaldehyde sensor in presence of light. The response in presence of light was obtained as 291.7% at 190 ppm with a fast response time of similar to 24 s and recovery time of similar to 42 s (at 190 ppm of formaldehyde). The sensor was found to be highly specific towards formaldehyde compared to other VOCs. The optimum operating temperature was similar to 300 degrees C, much less than the conventional NiO based sensors (similar to 600 degrees C). The sensing layer was made optically active by inducing defects which resulted in the dependence of the sensing response on light irradiation to a considerable amount (similar to 82.4% in dark and similar to 291.7% in light for 190 ppm formaldehyde). Thus, the fabricated light assisted sensor shows potential to develop future commercial formaldehyde sensor.