The relationship between surface open cells of α-MnO2 and CO oxidation ability from a surface point of view. Issue 39 (27th September 2017) - Li, Kezhi
Abstract : Open cells at the surface of α-MnO2 provide adsorption and oxidative sites for CO oxidation. Abstract : α-MnO2 is a widely reported material for catalysis reactions. However, due to its complicated structure with 2 × 2 tunnels, knowledge of the surface structure and its relationship with the catalytic performance for α-MnO2 is limited, even though the understanding of this is key for developing better catalysts. Herein, a surface-focused structure–performance relationship regarding the oxidation of CO is established in this work. It is shown that the 2 × 2 tunnels are open at the surface {100} planes via transmission electron microscopy (TEM), TEM simulation, and CeO2 probe deposition experiments. Since α-MnO2 is rod-like and wrapped with {100} planes, the surface of α-MnO2 consists mainly of this open cell structure. The open cells are rich in adsorption sites for O2 . Furthermore, these surface sites are also highly oxidative in nature. Owing to the fact that CO can react with surface oxygen species to yield CO2, the promoted adsorption of O2 and the oxidative surface sites will benefit CO oxidation over α-MnO2 . Thus, the superior performance for CO oxidation can be related to the open cell structure. This work not only establishes the surface structure–performance relationship, but also provides a new point of view for the understanding of the structure of α-MnO2 by emphasising the surface open cells.