Aqueous Synthesis of Mn₃O₄ Nanoparticle@MnOOH Nanobelt Heterostructures

A combined heterostructures with Mn3O4 nanoparticles attached to MnOOH nanobelts were prepared via an aqueous oxidation method at 90 °C with H2O2 as oxidant. The crystalline structures and morphologies of the as-prepared samples were detected by X-ray powder diffraction (XRD), field emission scanning electron microscope (FESEM) and high resolution transmission electron microscope (HRTEM) analysis, and the forming mechanism of Mn3O4@MnOOH nanomaterials was discussed. Crystalline composition and morphologies of samples changed with reaction time and crystallinity of Mn(OH)2 precursor. β-MnOOH nanoplates can be obtained in the initial reaction, then it transformed to γ-MnOOH nanobelts and/or Mn3O4 nanoparticles as reaction time increasing. The ratio of Mn3O4 in Mn3O4@MnOOH nanomaterials increased with the better crystallinity of Mn(OH)2 precursor. The as-prepared Mn3O4@MnOOH nanomaterials with varied compositions were used for degradation of Rhodamine B (RhB) in acid condition. The degradation reactions carried out in acid condition without stimulated light sources. The results showed that the manganese heterostructures had good activity based on synergy of Mn3O4 and MnOOH nanocrystals.