Potential oscillations in formic acid oxidation in electrolyte mixtures: Efficiency and stability

Potential oscillations were used to probe effects on the oxidation of formic acid from varying the fractions of H2SO4 and HClO4 in the supporting electrolyte. Two types of experiments were conducted. In one type the potential was induced to travel from low to high values by applying a large constant current. Results on the time of passage show the reaction process is more efficient with mixtures of the inorganic acids than with only H2SO4 or HClO4 in the supporting electrolyte. Oscillations accompanying the potential evolution reveal the rate of formation of species that inhibit reaction is less when mixtures of acids are used. In the second type of experiment, the applied current took the form of a staircase function. The current at each step was held at its constant value for no less than 15 min. It was found that the range of stability for behaviors seen with only H2SO4 or HClO4 in the supporting electrolyte is considerably shorter than the stability range of a behavior obtained using mixtures of the two acids.