| Abstract: Potassium manganese oxides were prepared by cathodic deposition from aqueous KMnO4 solution on an indium tin oxide slide. The products were characterized by XRD, XPS and SEM techniques. The as-prepared products were potassium manganese oxides with different manganese valence states. The component, morphology and size of the products could be controlled through adjusting the preparation parameters such as deposition potential, deposition time and acidity of the electrolyte. The results show that the deposition of potassium manganese oxide from aqueous KMnO4 is a pH value dependent procedure. Due to the facilitating of intercalation and deintercalation of cations, the specific capacitance of the products deposited for 500 s is higher than that of 3 000 and 6 000 s. At a scan rate of 2 mV·s-1 in 0.2 mol·L-1 K2SO4 aqueous electrolyte, the specific capacitances of products are 119.4, 99.5 and 109.0 F·g-1 corresponding to the deposition time of 500, 3 000 and 6 000 s, respectively. Electrochemical experiments indicate that the reversibility and performance of these potassium manganese oxides are also changed with the deposition time. |
