Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 17: Solid-liquid interfaces: Reactions and electrochemisty I (joint session O/CPP)

O 17.5: Vortrag

Montag, 12. März 2018, 16:00–16:15, MA 144

Driving hyrodrogen evolution and oxidation on Pt with femtosecond laser pulses — •Gregor Zwaschka, Yujin Tong, Martin Wolf, and R. Kramer Campen — Fritz Haber Institute of the Max Planck Society, Berlin, Germany

The Hydrogen Evolution and Oxidation Reactions (HER/HOR) on Pt have been studied for decades due to their fundamental interest and importance in applications such as electrolyzers and fuel cells. Despite much effort there is no clear view of the mechanism of these reactions that can explain the large dependence of their rates on surface structure, pH and electrolyte. Because the HER/HOR on Pt are fast, one possible explanation for the challenge in obtaining such mechanistic insight is that intermediates exist on the Pt electrode surface at very low concentrations under steady state reactive conditions. In principle such a limit can be overcome by rapidly and transiently increasing the amount of reactants present and characterizing their effect. Here we present our efforts to trigger the HER/HOR on Pt using femtosecond laser pulses. The resulting, laser-induced voltammogram clearly shows that the femtosecond pulse train induces HER/HOR and that the magnitude of this effect depends on crystal face in a manner rationalizable by the surface electronic structure. Control experiments varying pulse lengths, energies and the frequencies of the incident field suggest that we induce the HER/HOR by creating a population of hot electrons. Theses results offer a novel experimental window on the HER/HOR and are a first step in experimentally characterizing the mechanisms of these important reactions.