New insights into the effect of morphology on catalytic properties of MnO -CeO mixed oxides for chlorobenzene degradation.

We synthesized four CeO-MnO mixed oxides with different morphologies using simple hydrothermal methods. The catalytic activity for chlorobenzene (CB) degradation decreases in the following order: rod-CeO-MnO > plate-CeO-MnO > polyhedra-CeO-MnO > cube-CeO-MnO . CeO and MnO in the mixed oxides are highly dispersed and two new phases of both todorokite (S.G.: 2/:) and vernadite (S.G.: 4/) with a special tunnel-like structure are found. Both rod-CeO-MnO and plate-CeO-MnO exhibit increased lattice microstrains generated from lattice distortion and defects; further, there are more oxygen vacancies and more MnO (Mn and Mn) species on the surface, particularly when compared to cube-CeO-MnO . Therefore, this promotes deeper oxidation activity for CB. Moreover, the strong interaction between CeO and MnO also promotes the redox ability of CeO-MnO 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.