2018 Volume 126 Issue 11 Pages 906-913
Manganese dioxide having nanorod and nanoflake morphologies have been successfully prepared by electrolysis of KMnO4 at a temperature of 60°C. The acidity of the solution substantially influenced the particle morphology. The particles had nanorod morphology at a very acid solution (pH 0.2) whereas they had nanoflake shape at the base condition (pH 9). X-ray diffraction analysis revealed that the particles generated at very acid condition were α-MnO2. On the other hand, the particles synthesized at base condition were amorphous MnO2. The electrocatalytic activity towards oxygen reduction reaction (ORR) of the materials was studied in oxygen-saturated 0.6 M KOH solution. The electrons transferred per oxygen molecules of ORR for nanorod and nanoflake MnO2 particles were 2.23 and 1.75, respectively. The results suggest that nanorod MnO2 particles exhibit better ORR activity corresponding to 2-electron transferred ORR mechanism.