Manganese Dioxide Electrode: Part 1.—Hydrogen Ion Response in the Absence of other Cations

Abstract

Potential against pH plots have been obtained for a “hydrogen form” electrodeposited γ-manganese dioxide and for a “hydrogen form”β-manganese dioxide ore. The electrolyte solution was hydrochloric acid; no cations other than hydrogen ions were present. The plots were straight lines with a slope of –0.059 V/pH and changes of pH caused no hysteresis. Changing the electrolyte to sulphuric acid did not affect the potential against pH relationship. When other cations are present, the effects on the potential against pH plot caused by ion exchange between the manganese dioxide and these cations, can be minimised by an extrapolation procedure.

The potential determining reaction for manganese dioxide is most probably MnO2+ H++ e ⇌ MnOOH.