Berlin 2024 – scientific programme

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O: Fachverband Oberflächenphysik

O 39: Poster: Metal Substrates

O 39.5: Poster

Tuesday, March 19, 2024, 18:00–20:00, Poster D

On-top hydrogen adsorption on Pt(111): A complementary studies by LEED, TPD and sum-frequency generation spectroscopy — •Zhipeng Huang, Tobias Roos, Yujin Tong, and R. Kramer Campen — Faculty of Physics and Center of Nanointegration (CENIDE), University of Duisburg-Essen

Studying the hydrogen (H) adsorption on a metal surface is important for understanding the hydrogen evolution and oxidation reactions occurring at catalytic metal surfaces. However, there remain controversies on whether hydrogen can be adsorbed on-top sites stably even for the most-stable and close-packed (111) surface of platinum (Pt) under well-defined UHV conditions.

Here we present our studies on hydrogen adsorption on Pt(111) by the surface sensitive thermal desorption spectroscopy (TDS), low-energy electron diffraction (LEED) and vibrational-resonant sum-frequency generation spectroscopy (VSFG). We found that the stable adsorption sites of hydrogen on Pt(111) depend strongly on the substrate temperature when dosing hydrogen. The on-top adsorbed hydrogen is observed by both LEED and VSFG when dosing hydrogen with the substrate temperature at 210 K. We systematically studied the on-top adsorbed hydrogen on Pt(111) under different coverages using VSFG and revealed how the lateral interaction affects the on-top hydrogen-Pt vibrational frequency. Our results indicate that the prepared on-top adsorbed hydrogen might be accessed through a local equilibrium and different than that predicted by current generations of theory.

Keywords: LEED; VSFG; hydrogen adsorption