Photon-Assisted Ultra-Selective Formaldehyde Sensing by Defect Induced NiO-Based Resistive Sensor

Indoor air quality (IAQ) monitoring is essential to maintain healthy human life. Among different pollutants affecting IAQ, formaldehyde is one of the toxic volatile organic compounds (VOC) that needs to be monitored. In this paper, hierarchical NiO nanostructure sensing layer was used as highly sensitive formaldehyde sensor in the presence of light. The response was found to be 292% in the presence of 190 ppm formaldehyde with a fast response ~24 s and recovery ~42 s time. The sensor was found to be highly specific towards formaldehyde compared to other VOCs. The LOD calculated for the sensor was as low as 910 ppb. The optimum operating temperature was found to be ~300°C, much less than the conventional NiO-based sensors (~600°C). The sensing layer was found to be optically active due to the induced defects in the NiO nanostructure. Thus, the fabricated light-assisted sensor shows potential for future commercial formaldehyde sensor.