The key elements in the mechanism of the formic acid oxidation reaction on platinum have been completely elucidated, not only for the direct path through an active intermediate, but also for the CO formation route.

Abstract.The effects of solution pH and anion adsorption for the formic acid oxidation reaction on the Pt(111) electrode have been examined using electrochemical techniques. Regarding the pH effects, it has been found that oxidation currents for this reaction increases as the pH increases, which indicates that solution formate is involved in the reaction mechanism.Unexpectedly, the adsorption of sulfate on the Pt(111) electrode has a positive effect on the oxidation of formic acid, which also suggests that adsorbed anions are also involved in the mechanism. The activation energy calculated from temperature dependent measurements diminishes with the solution pH and also in the presence of adsorbed sulfate. These measurements corroborate the involvement of solution formate and anions in the oxidation mechanism. Using these results, a rate equation for the oxidation of formic acid is proposed.The current values calculated from this equation are in very good agreement with the experimental currents in perchloric acid solutions.

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In order to improve catalytic processes, elucidation of reaction mechanisms is essential. Here, supported by a combination of experimental and computational results, the oxidation mechanism of formic acid on Pt(111) electrodes modified by the incorporation of bismuth adatoms is revealed. In the proposed model, formic acid is first physisorbed on bismuth and then deprotonated and chemisorbed in formate form, also on bismuth, from which configuration the C−H bond is cleaved, on a neighbor Pt site, yielding CO 2 . It was found computationally that the activation energy for the C−H bond cleavage step is negligible, which was also verified experimentally.

The engineered search for new catalysts requires a deep knowledge about reaction mechanisms. Here, supported by a combination of computational and experimental results, the oxidation mechanism of formic acid on Pt(111) electrodes modified by adatoms of the pblock is elucidated for the first time. DFT calculations reveal that some adatoms, such as Bi or Pb, have positive partial charge when adsorbed on the bare surface whereas others, Se or S, remain virtually neutral. When the partial charge is correlated with previously reported experimental results for the formic acid oxidation reaction, it is found that the partial positive charge is directly related to the increase in catalytic activity of the modified surface. Further, it is obtained that such a positive partial charge is directly proportional to the electronegativity difference between the adatom and Pt. Thus, the electronegativity difference can be used as an effective descriptor for the expected electrocatalytic activity. Furthermore, this partial positive