Ground-level ozone is an irritant and is harmful to human respiratory and nervous systems. Thus, four manganese oxides with different crystals were hydrothermally synthesized to decompose residual ozone (deO3) in an ozone synergistic-oxidation system. Among them, a cactus-like MnO2-IV nanosphere exhibited the highest deO3 activity, with excellent tolerance to water vapor and SO2/H2O, which could maintain >88% deO3 efficiency in the high-humidity and sulfur-containing conditions. It benefits from the unique morphology, high specific surface area, superior redox properties, oxygen chemisorption capabilities, abundant surface-active hydroxyl species, and low valence Mn species. More importantly, the detailed interference mechanism of O2/O3/H2O/SO2 molecules on MnO2-IV was revealed utilizing in situ diffused reflectance infrared Fourier transform spectroscopy and X-ray photoelectron spectroscopy. H2O generally caused recoverable deactivation, but that caused by SO2 was irreversible. The synergistic effect of SO2/H2O promoted the formation of an unstable sulfate species, thereby deepening the deactivation but inhibiting the irreversible poisoning. Finally, nine specific steps to decompose ozone via surface-active hydroxyl/intermediates were established.
© 2022 The Authors. Published by American Chemical Society.