Formic Acid Oxidation on Shape-Controlled Pt Nanoparticles Studied by Pulsed Voltammetry

Pulsed voltammetry was used to study formic acid electrooxidation on Pt nanoparticles with well-characterized surfaces. Polyoriented and preferential (100), (100-111), and (111) Pt nanoparticles were characterized and employed to evaluate the influence of the surface structure and shape of the Pt nanoparticles on this model electrochemical reaction. The results pointed out that, in agreement with fundamental studies with Pt single crystal electrodes, the surface structure of the electrodes plays an important role on the reactivity and kinetics of formic acid oxidation. Thus the electrocatalytic properties for this reaction strongly depend on the dominant structure on the surface of the nanoparticles, in particular on the presence of domains with (100) and (111) symmetry. Among the Pt nanoparticles studied, those containing (100) domains are clearly the most active toward formic acid electrooxidation via the active intermediate path, but also exhibit the highest poisoning rate. (111) Pt nanoparticles show the lowest CO formation constant in the series and a moderate reaction rate via the active intermediate reaction path.