Highly Sensitive and Selective Gas Sensors for Ethanol Based on Mn Doped ZnO Nanoflakes

Low-operating temperature gas sensors play a pivotal role in environmental and health safety. Here, we investigate the performance of hexagonal ZnO nanostructures for detecting hazardous ethanol gas. Pure and 3% Mn doped ZnO thin films were synthesized by a spray pyrolysis method. The study focused on investigating structural, morphological, chemical composition, optical and gas sensing properties of these films. By adding 3% Mn doping, the structural, morphological and optical properties of ZnO film notably changed. The 3% Mn-doped ZnO thin film exhibits a high response of 360 compared to undoped ZnO (154) towards 50 ppm of ethanol at room temperature. This may be due to the increased surface reactivity and defects sites. The response/recovery time of the Mn-doped ZnO to ethanol is found to be 18/40s. Gas sensing studies suggest that the 3% Mn-doped ZnO thin film has good reproducibility, stability and selectivity. The sensing mechanism of ethanol by Mn-doped ZnO thin films is studied and discussed. These findings suggest that Mn-doped ZnO thin films are promising candidates for low temperature ethanol sensing application.