Catalytic Decomposition of Residual Ozone over Cactus-like MnO(2) Nanosphere: Synergistic Mechanism and SO(2)/H(2)O Interference

[Image: see text] 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 (deO(3)) in an ozone synergistic–oxidation system. Among them, a cactus-like MnO(2)-IV nanosphere exhibited the highest deO(3) activity, with excellent tolerance to water vapor and SO(2)/H(2)O, which could maintain >88% deO(3) 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 O(2)/O(3)/H(2)O/SO(2) molecules on MnO(2)-IV was revealed utilizing in situ diffused reflectance infrared Fourier transform spectroscopy and X-ray photoelectron spectroscopy. H(2)O generally caused recoverable deactivation, but that caused by SO(2) was irreversible. The synergistic effect of SO(2)/H(2)O 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.