UV-Induced Room-Temperature Ethylene Sensors Based on Ag-Decorated ZnO Nanoflowers for Fruit Ripeness Monitoring

Monitoring of plant hormone ethylene plays a crucial role in managing the growth and development of plants, especially in the ripening of fruits and the opening of flowers. Here, a highly sensitive ethylene sensor is demonstrated using silver nanoparticle (Ag NP)-decorated zinc oxide nanoflowers (ZnO NFs), prepared through a facile and low-temperature chemical synthesis. The results indicate that Ag NP decoration on the surface of ZnO NFs improved the ethylene sensing properties under ultraviolet (UV) illumination. With an optimized UV light intensity of 5 mW/cm², the sensing response to 40 ppm of ethylene gas increased from 13.27% to 52.83%. The sensors exhibit a strong linear response to ethylene gas within the range of 10–70 ppm, with a low detection limit of 5 ppm. Moreover, the Ag-decorated ZnO NFs sensors demonstrated good repeatability, excellent long-term stability, and high selectivity toward ethylene gas. The sensing mechanism is attributed to the catalytic effectiveness and localized surface plasmon resonance of Ag NPs. These results suggest that UV-induced Ag-decorated ZnO NFs are promising for practical application in fruit ripening monitoring for supply chain management.