Facile synthesis of hierarchical Mn 3 O 4 superstructures and efficient catalytic performance.

The development of novel materials with excellent performance depends not only on the constituents but also on their remarkable micro/nanostructures. In this work, manganese oxide (Mn3 O4 ) hausmannite structures with a uniform three-dimensional (3D) flower-like hierarchical architecture have been successfully synthesized by a novel chemical route using surfactants as structure-directing agents. Microstructure analysis indicates that the obtained 3D flower-like Mn3 O4 superstructure consists of a large number of two-dimensional (2D) Mn3 O4 nanosheets, which is different from the reported 3D Mn3 O4 hierarchical structures based on zero-dimensional nanoparticles or one-dimensional nanowires and nanorods. This 3D Mn3 O4 hierarchical architecture provides us with another type of manganese oxide with different superstructural characteristics, which may have potential practical applications in the catalytic degradation of organic pollutants. The catalytic performance of this hierarchical Mn3 O4 superstructure, which was prepared by three different types of structure-directing agents, including cetyltrimethylammonium bromide (CTAB), poly(vinylpyrrolidone) (PVP), and poly(ethylene oxide)-poly(propylene oxide) (P123), was evaluated for the catalytic degradation of organic pollutants, e.g. methylene blue. Interestingly, the hierarchical Mn3 O4 superstructure prepared using CTAB as a template showed efficient catalytic degradation. The formation processes and possible growth mechanism of this novel 3D Mn3 O4 hierarchical superstructure assembled by 2D Mn3 O4 nanosheets are discussed in detail.