Reduction of KMnO4 to Mn3O4 via hydrothermal process

Abstract A simple, inexpensive, low temperature and environmentally benign hydrothermal reduction route has been developed for the synthesis of octahedral Mn3O4 nanoparticles by using KMnO4 and hexamethylenetetramine (HMT). It has been found that, Mn3O4 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 Mn3O4. The powder X-ray diffraction (XRD) data confirms the formation of tetragonal γ-Mn3O4. Scanning electron micrograph images exhibit a good octahedral morphology of the product. The formation γ-Mn3O4 is further confirmed by Raman and FTIR spectroscopy.