OXYGEN REDUCTION ON A ROTATING PT DISC ELECTRODE IN FORMIC ACID-CONTAINING SOLUTIONS

The effect of HCOOH on the reduction of oxygen in sulfuric acid soluti on is investigated by using a rotating Pt disc electrode. The reductio n of oxygen and the oxidation of HCOOH during the negative potential s weep interfere with each other. When the concentration of HCOOH is les s than 0.01 mol dm(-3), the reduction of oxygen is not affected at hig her potentials. However, the oxidation of HCOOH is completely suppress ed, probably owing to the consumption of adsorbed HCOOH fragments thro ugh reaction with oxygen. The results show that the electrode activity for the reduction of oxygen becomes unacceptable when the HCOOH conce ntration is higher than 0.1 mol dm(-3), since the potential for the on set of the reduction of oxygen shifts in a very negative direction. It is suggested that the decrease in the activity of the reduction of ox ygen is due to the adsorption of HCOOH fragments on the electrode sufa ce. However, there is no evidence that the mechanism of the reduction of oxygen is altered by the adsorption of HCOOH.