Manganese (Mn2+) doped hexagonal prismatic zinc oxide (ZnO) nanostructures for chemiresistive NO2 sensor

Low-operating temperature gas sensor is of great significance in a range of environmental and health safety. Here, we present the operation and performance of hexagonal prismatic ZnO nanostructures (NSs) for detection of toxic nitrogen dioxide (NO2). Mn nanoparticles (NPs) were incorporated into ZnO at various concentrations, and X-ray diffraction (XRD) patterns delineated a wurtzite hexagonal phase. From Tauc's plot, the band gap (Eg) for the NSs found to be ∼3.15–3.17 eV. The photoluminescence (PL) spectra showed a strong near-band edge emission (NBE) concordant with the calculated Eg. The NO2 response measurements showed a significant perceptual behavior of NO2. The NO2 responses increased with increasing Mn dopant concentrations. The maximum response of 152.3 % and 126.9 % was acquired for 2 % and 4 % Mn-doped ZnO at 75 °C. The response and recovery times for the sensor towards ten ppm NO2 are 107 s and 158 s. Better repeatability was achieved with good stability. These results bring promise to low operating temperature, low cost NO2 sensor based on ZnO, which could possibly used as real time monitoring.