Thermal characterisation of chemically reduced electrolytic manganese dioxide

Summary

Samples of electrolytic manganese dioxide (EMD) were chemically reduced using 2-propanol under reflux (82°C) for 1, 2, 3, 6 and 24 h intervals. XRD analysis showed that the γ-MnO₂ structure was preserved although the lattice dimensions were observed to increase with increasing degree of reduction to accommodate the intercalation of protons. The exception was the 24 h reduced sample which contained two phases; γ -MnO₂ and γ -MnOOH. Three regions of decomposition in the range of 50 to 1000°C were observed using thermogravimetric analysis coupled with mass spectrometry (TG-MS) and were accounted for as water removal below 390°C, reduction of MnO₂ to Mn₂O₃ between 400 and 600°C, and Mn₂O₃ to Mn₃O₄ between 600 and 1000°C. Again the exception proved to be the 24 h reduced sample which was observed to decompose predominantly in one step between 400 and 600°C directly to Mn₃O₄.