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O: Fachverband Oberflächenphysik

O 25: Metal substrates: Adsorption of organic / bio molecules III

O 25.8: Vortrag

Dienstag, 23. März 2010, 12:15–12:30, H36

Oxidation of Formic Acid on Pt(111) — •Wang Gao and Timo Jacob — Universität Ulm, Albert-Einstein-Allee 47, D-89069 Ulm, Germany

Oxidation of formic acid (HCOOH) on Pt(111) surfaces, which can be considered a benchmark reaction to probe the corresponding electrocatalytic HCOOH conversion in fuel cells, has been studied using density functional theory. The effects of water and adsorption coverage on the process from HCOOH to CO₂ were investigated in detail. For each reaction pathway we evaluated relative energies under different environmental conditions, including activation barriers, reaction energies, and intermediate and transition state structures. Our results indicate that while the direct conversion is energetically unfavorable both HCOO and COOH could be reactive intermediates. Moreover, surrounding or co-adsorbed water turned out to play a key role in the whole process, which drastically influences the stability of reactants and products on Pt(111), as well as the correlated reaction barriers. Meanwhile, the entire catalytic process additionally varies with surface coverage, making the formic acid oxidation a rather complex reaction. Based on our energetics, future analysis of the reaction kinetics will elucidate preferred reaction mechanisms.