Ozone Decomposition below Room Temperature Using Mn-based Mullite YMn 2 O 5 .

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