Ozone Decomposition below Room Temperature Using Mn-based Mullite YMn<sub>2</sub>O<sub>5</sub>
Xiang Wan, Lijing Wang, Shen Zhang, Haozhe Shi, Juntao Niu, Gen Wang, Weifang Li, Da Chen, Haijun Zhang, Xiaomeng Zhou, Weichao Wang
Abstract
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 O22– 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.