Rational design of MnO2@MnO2 hierarchical nanomaterials and their catalytic activities

Hierarchically structured materials have special properties and possess potential in applications in the catalytic and electrochemical fields. Herein, two kinds of hierarchical core shell nanostructures, lavender-like alpha-MnO2@alpha-MnO2 and balsam pear-like alpha-MnO2@gamma-MnO2, were prepared by a facile room temperature method using alpha-MnO2 nanowires as a backbone under acidic and alkaline conditions, respectively. When being used as a catalyst for dimethyl ether combustion, alpha-MnO2@gamma-MnO2 exhibited a better performance than alpha-MnO2@alpha-MnO2 (T-10 = 171 vs. 196 degrees C; T-90 = 220 vs. 258 degrees C, SV = 30, 000 mL g(-1) h(-1)). It is concluded that the larger surface area, higher reducibility/oxygen mobility, richer surface oxygen species, and the relatively smaller apparent activation energy are responsible for the superior performance of alpha-MnO2@gamma-MnO2.