SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 94: Poster Session VII: Poster to Mini-Symposium: Electrified solid-liquid interfaces II
O 94.4: Poster
Donnerstag, 4. März 2021, 10:30–12:30, P
Under potential deposited Hydrogen on Pt(111) is both terminal and bridge-bonded — Gregor Zwaschka1,2, Yujin Tong1,2, and •R. Kramer Campen1,2 — 1Fritz Haber Institute of the Max Planck Society, Berlin, Germany — 2University of Duisburg-Essen, Duisburg, Germany
Despite decades of effort, finding catalysts for either half reaction of electrolytic water splitting that are reactive, stable and inexpensive has proven remarkably challenging. For the hydrogen evolution half reaction (HER) in acidic solution platinum meets the first and second of these goals remarkably well but understnading why it does so, i.e. understanding the mechanism of the HER on Pt, has proven challenging.
H adsorbs on Pt at potentials positive of those at which H2 appears. Understanding the potential-dependent structure of this under-potential-deposited (UPD) H, how it differs from H adsorbed on Pt in UHV, and its relationship to H2 generation is a necessary step in understanding the HER mechanism. Here we perform vibrational sum frequency spectroelectrochemistry to collect the potential dependent Pt-H spectral response on single crystal Pt(111) electrodes in acidic solution. In contrast to suggestions from UHV and previous infrared spectroelectrochemical studies, we find that both terminal and bridge-bonded H appear throughout the UPD region and that, depending on the defect density, distinct types of terminal-bonded hydrogen can be observed. Intriguingly, for pristine Pt(111) surfaces we also observe an interfacial hydronium species heretofore only predicted in calculation.