Hydrothermal synthesis of spherical nanoflower ZnO with highly sensitive isoprene sensing performance

As a typical physiological marker, isoprene has been widely studied for its related applications in breath detection. Pure ZnO samples were prepared using the classical hydrothermal method with varying synthesis parameters. By comparing these parameters, the optimal synthesis conditions and nanostructures were determined. The prepared spherical ZnO nano-flower material (ZnO-S5 sample) exhibited a loose and porous structure. Additionally, the gas sensing sensors were prepared with ZnO-S4 and ZnO-S5 samples respectively, and their gas-sensing characteristics were analyzed comprehensively. The data indicated that spherical nano-flower ZnO sensor (ZnO-S5) exhibited an optimal operating temperature of 260 °C, and the response time is only 5 s when the isoprene concentration is 0.2 ppm. It also demonstrated good repeatability and sustained stability. Notably, even at isoprene concentrations as low as 20 ppb, the ZnO-S5 sample still had obvious response, and the response value was approximately 3.3 times that of ZnO-S4. Simultaneously, when compared with other typical biomarkers such as hydrogen, carbon monoxide, ammonia, ethanol and acetone, ZnO-S5 sample has relatively better selectivity for isoprene. Therefore, the spherical nano-flower-like ZnO sensor holds promise as a low-cost, high-performance isoprene gas detector for the rapid identification of trace isoprene.