Reduction of KMnO_4 to Mn_3O_4 via hydrothermal process

摘要

A simple, inexpensive, low temperature and environmentally benign hydrothermal reduction route has been developed for the synthesis of octahedral Mn_3O_4 nanoparticles by using KMnO_4 and hexamethylenete-tramine (HMT). It has been found that, Mn_3O_4 formation during hydrothermal process involves two steps. In the first step, an intermediate MnOOH is formed under the influence of self generated pressure in the autoclave. In the second step, formic acid produced via hydrolysis followed by oxidation of HMT, reduces MnOOH to Mn_3O_4. The powder X-ray diffraction (XRD) data confirms the formation of tetragonal γ-Mn_3O_4. Scanning electron micrograph images exhibit a good octahedral morphology of the product. The formation γ-Mn_3O_4 is further confirmed by Raman and FTIR spectroscopy.