The catalytic degradation of ethylene by δ-MnO2 at room temperature and its application in the postharvest preservation of Prunus salicina ‘Wushan Plum’ fruit

This study developed two δ-MnO₂ catalysts synthesized via isopropanol reduction (MnO₂-iso) and ammonium chloride hydrothermal treatment (MnO₂-NH₄Cl) for room-temperature ethylene catalytic degradation. Characterizations, e.g., scanning electron microscope, X-ray diffraction and N₂ adsorption-desorption analysis, are employed to investigate the underlying mechanism of their ethylene-degradation differences. X-ray photoelectron spectroscopy indicates that the enhanced performance of MnO₂-iso primarily stems from its abundant surface defects, elevated Mn³⁺, and reactive oxygen species, relative to MnO₂-NH₄Cl. At 100 ppm ethylene over 8 h, MnO₂-iso achieves 66.9 % degradation efficiency compared to 46.1 % for MnO₂-NH₄Cl. Furthermore, when incorporated into composite labels for postharvest treatment of Prunus salicina ‘Wushan Plum’ fruit, both catalysts significantly reduce ethylene production by (28.5 % and 20.3 % by 12th day), delay respiration peaks by 2 d, better preserve fruits' key quality attributes, and extend fruits' shelf life by 3–5 d. These findings highlight δ-MnO₂ as an eco-friendly alternative for ambient ethylene oxidation in fruit preservation.