Spontaneously deposited manganese oxide on acetylene black in an aqueous potassium permanganate solution

Manganese oxide was deposited spontaneously on acetylene black by the simple immersion of the acetylene black into a KMnO4 aqueous solution via a one-step chemical process for application in electrochemical capacitors. Acetylene black was found to act as the reducing agent and substrate for the heterogeneous nucleation of manganese dioxide in an aqueous KMnO4 solution via the in situ monitoring of the reduction potential and pH of the solution and supplementary ultraviolet-visible analysis. The morphology of the acetylene black before and after depositing the manganese oxide was examined using scanning and transmission electron microscopy, which revealed several-nanometer-thick manganese oxide deposits on the acetylene black. X-ray diffraction and Raman spectroscopy showed that the manganese oxide deposited on the acetylene black was the birnessite-type. (c) 2005 The Electrochemical Society.