Bonding MnO2/Fe3O4 shell-core nanostructures to catalyze H2O2 degrading organic dyes

Shell-core nanostructures with both high catalytic activation and recyclability have been becoming hot property in nano-catalysis. By respectively using co-precipitation method, sol-gel method, and homogeneous precipitation method we manufactured shell-core nano-particles of Fe3O4 core and MnO2 shell. The Bonding mechanism of the composite is discussed in detail, and the efficiency and nature of the particles to degrade methyl orange by catalyzing H2O2 is also demonstrated. We show that by using homogeneous precipitation method one can obtain morphologically uniform nano-particles of about 5-6 nm MnO2 shell and 13-14 nm Fe3O4 core. The characteristic peak of Fe3O4 in the Infrared spectra of the composite particles was blue shifted, and a novel peak appears at 775.68 cm(-1) referring to occurrence of new bond. X-ray Photoelectron Spectroscopy analysis showed that the bonding energy of Fe2p and Ols was increased due to the combination of the MnO2 shell and the Fe3O4 core, suggesting a new bond of Fe-O-Mn occurred in the composite. The MnO2 shell has abundant hydroxyl radicals and exhibits high chemical activity in catalyzing H2O2 and degrading methyl orange with a degree of greater than 95%. On the other hand, the shell-core nanostructures are super-paramagnetic, and the saturated magnetization reaches 33.5 eum/g, which is sufficient for the catalyst to be recycled.