Ozone Decomposition below Room Temperature Using Mn-based Mullite YMn₂O₅

A super-low-temperature ozone decomposition is realized without energy consumption on a ternary oxide catalyst mullite YMn₂O₅ for the first time. The YMn₂O₅ oxide catalyzed ozone decomposition from a low temperature of -40 °C with 29% conversion (reaction rate: 1534.2 μmol g^-1 h^-1) and quickly reached 100% (5459.5 μmol g^-1 h^-1) when warmed up to -5 °C. The superior low-temperature performance over YMn₂O₅ could surpass that of the reported ozone decomposition catalysts. The structure and element valence characterizations confirmed that YMn₂O₅ remained the same after 100 h of room-temperature reaction, indicating excellent durability of the catalyst. O₂-TPD (O₂-temperature-programmed desorption) showed that the active sites are the Mn³⁺ sites bonded with singly coordinated oxygen on the surface. Combined with in situ Raman measurements and density functional theory calculations, we found that the ozone decomposition reaction on YMn₂O₅ showed a barrier of only 0.29 eV, following the Eley-Rideal (E-R) mechanism with a rate-limiting step of intermediate O₂^2- desorption. The low barrier minimizes the accumulation of intermediate products and realizes the fast O₃ decomposition even at super-low temperatures. Fundamentally, the moderate Mn-O bonding strength in the low-symmetry ternary oxides is crucial to produce singly coordinated active species on the surface responsible for the efficient ozone degradation at low temperatures.