Controlled-synthesis of β-MnO2 nanorods through a γ-manganite precursor route

Abstract

As a fascinating nanomaterial, one-dimensional particles have become today's research hotspot and awarded extensive interdisciplinary attention for sustainable development and industrial applications. Single crystal γ-manganite (γ-MnOOH) nanorods were synthesis via a hydrothermal procedure through an oxidation-reduction reaction between potassium permanganate as the precursor and ethane-1,2-diol as the reducing agent and solvent at 120 °C for 10 h. This procedure did not use any templates or surfactants. The structural and morphological control of the product is influenced by the reaction temperature and time. Following lamellar growth, assembly, and ripening routes, the hydrothermal procedure was employed for preparing nanorods of γ-MnOOH. These nanorods were subjected to thermal annealing at 400 °C for 4 h to yield β-MnO2 with single crystallinity, nanorod shape, 30 nm average width, 0.5–1 μm average length, and a [110] growth direction. The nanorod shape is retained during the transformation from γ-MnOOH to β-MnO2 through controlling the thermal annealing temperature. Characterization was carried out based on HRTEM, XRD, FESEM, X-ray photoelectron spectroscopy, and FTIR techniques. Novel properties and applications are expected for the prepared manganese oxide and oxyhydroxide nanorods.