Layered Double Hydroxide Catalysts for Ozone Decomposition: The Synergic Role of M and M.

In previous work, we successfully prepared a NiFe-layered double hydroxide (LDH) with superior activity and stability for catalytic ozone decomposition, which fundamentally avoids deactivation under high-humidity conditions. However, the role of the metal elements (M and M) in LDH catalysts is not clear. Here, LDH materials containing different metals (NiFe, NiAl, NiMn, CoFe, and MgFe) were prepared by a simple co-precipitation method. It was found that the LDHs containing Ni exhibited catalytic performance far superior to that of Co and Mg for ozone elimination, and NiFe-LDH had the best activity and stability among LDH materials prepared in this study. The NiFe-LDH can maintain 78% catalytic activity within 144 h at room temperature, even under a relative humidity of 65% and a space velocity of 840 L·g·h. Physicochemical characterizations demonstrated that chemical stability in an oxidizing atmosphere and the synergic role of M and M ions are crucial. The result of density functional theory calculation showed that the synergic role of Ni and Fe weakens the interaction between O and H in the O-H bond, which effectively lowers the reaction barrier of ozone decomposition compared with MgFe-LDH.