Stationary voltammogram for oxidation of formic acid on polycrystalline platinum

The stationary voltammogram does not depend on the sweep rate and shows the same curves in the positive and negative sweep directions. We successfully obtain, strictly speaking, a quasi one, for the oxidation of formic acid in a sulfuric acid solution at 42 °C at a sweep rate of 0.1 mV s - 1 . It takes a very long time to obtain one at lower temperatures. The voltammogram consists of a single current peak at 0.6 V in both the positive and negative sweep directions in the potential range between 0.05 and 1.4 V. It is quite different from the one measured at a normal sweep rate, e.g., 100 mV s - 1 , in that the latter has four current peaks in the same potential region. The shape of the stationary voltammogram is hardly affected by the temperature and the concentration of formic acid. Both the shape and current are hardly affected by the concentration of sulfuric acid, by the adsorption of anions, and by the mass transfer in solution. We have obtained electrochemical evidence that at the current peak potential, the adsorbed CO, the one reaction intermediate, is oxidized to produce CO 2 in the positive sweep direction and is formed in the negative sweep direction.