Increases in reaction rates and improvement of current¯potential characteristics in the electrochemical oxidation of formic acid

In current-control experiments, perturbing an aqueous solution containing 0.10 M formic acid and 0.50 M HClO4 by including a small amount of HBF4 causes more than a 60% increase in the value of the applied current for which low-valued stationary potentials remain stable. The current increases by more than 50% at relevant potential values in potential-control experiments. Current¯potential characteristics inferior to those of the HCOOH + HClO4 solution are obtained with other solutions made by adding small amounts of a strong acid or salt. Properties that exist among the anions present in the latter solutions are possessed by BF4-. Nonlinear behavior exhibited by formic acid oxidation is changed drastically by the presence of a small amount of any one of the anions studied. These results and other arguments support the hypothesis that HBF4 enhances current¯potential characteristics by causing the formation of surface anion complexes possessing OH components at low potentials.