Branched Mesoporous Mn3O4 Nanorods: Facile Synthesis and Catalysis in the Degradation of Methylene Blue

Branched MnOOH nanorods with diameters in the range of 50150 nm and lengths of up to tens of micrometers were prepared by using potassium permanganate (KMnO4) and PEG 400 (PEG=polyethylene glycol) as starting materials through a simple hydrothermal process at 160 degrees C. After annealing at 300 degrees C under a N2 atmosphere for 5 h, MnOOH nanorods became gradually dehydrated and transformed into mesoporous Mn3O4 nanorods with a slight size-shrinking. The as-obtained mesoporous Mn3O4 nanorods had an average surface area of 32.88 m2?g-1 and a mean pore size of 3.7 nm. Through tuning the experimental parameters, such as the annealing atmosphere and temperature, beta-MnO2, Mn2O3, Mn3O4, MnO, and Mn5O8 were selectively produced. Among these structures, mesoporous Mn3O4 nanorods were efficient for the catalytic degradation of methylene blue (MB) in the presence of H2O2 at 80 degrees C.