New insights into the effect of morphology on catalytic properties of MnO(x)–CeO(2) mixed oxides for chlorobenzene degradation

We synthesized four CeO(2)–MnO(x) mixed oxides with different morphologies using simple hydrothermal methods. The catalytic activity for chlorobenzene (CB) degradation decreases in the following order: rod-CeO(2)–MnO(x) > plate-CeO(2)–MnO(x) > polyhedra-CeO(2)–MnO(x) > cube-CeO(2)–MnO(x). CeO(2) and MnO(x) in the mixed oxides are highly dispersed and two new phases of both todorokite (S.G.: P2/m:b) and vernadite (S.G.: I4/m) with a special tunnel-like structure are found. Both rod-CeO(2)–MnO(x) and plate-CeO(2)–MnO(x) exhibit increased lattice microstrains generated from lattice distortion and defects; further, there are more oxygen vacancies and more MnO(x) (Mn(4+) and Mn(2+)) species on the surface, particularly when compared to cube-CeO(2)–MnO(x). Therefore, this promotes deeper oxidation activity for CB. Moreover, the strong interaction between CeO(2) and MnO(x) also promotes the redox ability of CeO(2)–MnO(x) mixed oxides, while their oxygen storage capacity (OSC) properties are not only intrinsic to their structures but also limited to their surfaces and by their particle sizes.