In-situ raman spectroscopy of manganese dioxide during the discharge process

Abstract

The discharge reduction process of an electrodeposited MnO2 layer was measured by Raman spectroscopy under in-situ conditions with MnO2/Au electrodes. The Raman spectrum of the MnO2 layer on Au changes with potential in a reversible manner. From 0.80 V to 0.20 V there are almost no changes in the Raman spectrum, although a small cathodic current of a few μA flows on the voltammogram, as shown in Fig. 3. The small amount of cathodic charge in this potential region may not introduce any important change in the MnO2 lattice. At potentials more negative than 0.20 V the Raman peak disappears. It may therefore be suggested that the reduction in this potential exceeds a critical point for the transformation of the MnO2 + MnOOH single phase, beyond which the reduction product cannot maintain the same lattice structure as that of the oxidized form of MnO2. © 1988.