Preparation of Mn5O8 and Mn3O4 nano-rods through cathodic electrochemical deposition-heat treatment (CED-HT)

Abstract

A novel cathodic electrochemical deposition (CED) procedure followed by a heat treatment (HT) step was developed for the preparation of Mn5O8 nano-rods. The CED was performed on a 0.005 M MnCl2 under a galvanostatic condition and a current density of 10 mA cm−2. The products were characterized through x-ray diffraction, FT-IR and SEM analyses, which proved the formation of Mn3O4 nano-rods as intermediates. The probable reactions leading to the CED formation and growth of nano-rods on the cathode surface were evaluated and discussed. To finalize the reaction and convert the Mn3O4 to the end product, the nano-rods were next subjected to the HT stage in an oxygen containing atmosphere to form Mn5O8 nano-rods. The end product of this step was also evaluated by the same analytical techniques as the intermediate product. SEM results indicated that the HT step does not influence the morphology of the intermediate nano-particles, while the DSC-TG analysis of the thermal behavior Mn3O4 nano-rods under the HT step revealed the possibility of physicochemical changes leading to the formation of Mn5O8 and hence the CED-HT method was considered as a novel method for the preparation of both Mn3O4 and Mn5O8 nano-rods with uniform size distribution.