Potential oscillations during methanol oxidation at Pt-electrodes .1. Experimental conditions

Potential oscillations during anodic methanol oxidation are studied by galvanostatic step experiments. Two types of galvanostatic step experiments are conducted by starting from an initial potential of approximately 450 and 20 mV respectively. Owing to the variation of the initial potential two potential regions are observed with oscillations of different shapes, frequencies and amplitudes. Oscillations, which occur at more negative potentials are generated by a small cathodic current before the galvanostatic step is performed. By applying a small cathodic current at the electrode the potential is kept below 50 mV, in a potential region where no methanol residues are formed. The type of oscillation, which occurs at higher potentials is independent of the initial experimental procedure. These results show that obviously different mechanisms are responsible for the observed oscillations.