Separate current range for appearance of potential oscillation during methanol oxidation on platinum

Abstract

We have found that the current range is divided into two parts for the appearance of potential oscillation during methanol oxidation on polycrystalline platinum at 315K when the methanol concentration is between 10 and 0.03 moldm-3 (M). The current range for oscillation disappearance, named ΔI (od), increases with a decrease in the methanol concentration. At currents below the ΔI (od), the oscillation waveform is always a large-amplitude and long-period (sometimes of the order of an hour) oscillation, named oscillation L. At currents immediately above the ΔI (od), a small-amplitude and short-period oscillation, named oscillation S, is observed for 0.03 to 0.1M methanol and oscillation L is for 0.3 to 10M methanol. For the latter methanol concentrations, oscillation S also becomes observed at higher currents. Such a ΔI (od) has not been found for potential oscillations during formic acid or formaldehyde oxidation and, thus, the existence of the ΔI (od) is distinctive to potential oscillations during methanol oxidation. © The Electrochemical Society of Japan, All rights reserved.