[3E01-11] Surface Science / Chemical Property (SS2)

9:15 AM - 9:30 AM JST(12:15 AM - 12:30 AM UTC)

[3E02] Interfacial Water Organization at Hydrogen-Covered Pt(111): Insights from Phase-Sensitive SFG and TPD

*Yuta Takahara^1,2, Hibiki Tsunekawa^1,2, Tatsuto Mochizuki^1,2, Shota Takahashi², Tsuneto Kanai², Atsunori Sakurai^1,2, Toshiki Sugimoto^1,2 (1. Graduate Institute for Advanced Studies, SOKENDAI (Japan), 2. Institute for Molecular Science (Japan))

We investigated interfacial water organization on hydrogen-covered (H-covered) Pt(111) under ultra-high vacuum conditions, using this surface as a well-defined model of Pt-H interfaces relevant to key intermediates in the hydrogen evolution reaction (HER). Phase-sensitive vibrational sum-frequency generation spectroscopy provides direct evidence that first-layer water molecules exhibit a net H-down orientation even on an H-covered Pt surface under zero-bias conditions. TPD measurements and vibrational frequency analysis demonstrated that hydrogen preadsorption weakens water–Pt interactions, while the H-down interfacial water structure remains robust. The experimentally observed organization is consistent with recent electrochemical simulations of interfacial water on H-covered Pt(111) and provide key structural insight into interfacial water organization, advancing mechanistic investigations of HER and related electrochemical reduction reactions.

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