MECHANISTIC STUDIES OF THE POTENTIAL OSCILLATION AND INDUCTION PERIOD IN THE OXIDATION OF FORMIC-ACID ON PLATINUM

The reaction mechanism of the potential oscillation and its induction period of formic acid oxidation on platinum is studied using a voltammogram. The reaction conditions are galvanostatic and the solution is acidic. The induction period is caused by an insufficient amount of adsorbed poisonous species, labelled D1, which has been identified as CO linearly adsorbed on Pt. Although slow potential increases at around 0.5 vs rhe during the oscillation are due to the accumulation of D1, rapid increases and decreases between 0.6 and 0.8 V are due to a different adsorbed species, labelled D2. This species is mainly poisonous at approximately 0.6 V, while it is mainly reactive to D1 at the upper oscillation potential limit, 0.7 0.8 V. The most probable candidate for D2 is water adsorbed adjacent to CO.