Highly selective ethanol detection on sheet-like ZnO sensor synthesized by microemulsion

Sheet-like ZnO nanoparticles (SZNs) were synthesized using a microemulsion method and characterized by XRD, BET, DRS, and FESEM techniques. These nanoparticles were then utilized as selective ethanol sensors operating at temperatures between 300 and 450 °C. When precursor ZnO concentrations were high, the average particle size of the SZNs increased, which was reflected in the sharper diffraction peaks observed in the XRD results. The low band gap of SZNs, attributed to their 2D morphology, was confirmed by the Tauc diagram. The SZN sensors demonstrated a remarkable selectivity for ethanol, with response levels up to 77 times higher than for CO and 3700 times higher than for CH₄, achieving a limit of detection between 2.7 and 13.3 ppm. By fine-tuning the microemulsion conditions, the SZN4 sensor achieved an exceptionally high response to ethanol, about 106 times, and up to 30 times higher compared to TCE, toluene, and propane. Furthermore, the SZN4 and SZN5 sensors exhibited a relative insensitivity to humidity, with only a 26% and 17% reduction in ethanol response, respectively.