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The Nature of Hydrated Protons on Platinum Surfaces
Author(s) -
Kim Youngsoon,
Noh Chanwoo,
Jung YounJoon,
Kang Heon
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201703882
Subject(s) - overlayer , chemistry , proton , adsorption , hydrogen , electrolysis of water , metal , dissolution , ion , platinum , inorganic chemistry , density functional theory , spectroscopy , chemical physics , electrolysis , computational chemistry , catalysis , electrolyte , biochemistry , physics , organic chemistry , electrode , quantum mechanics
The nature of hydrated protons formed at water/metal interfaces is one of the most intriguing research questions in the field of interfacial chemistry. We prepared coadsorption layers of hydrogen and water on a Pt(111) surface in ultrahigh vacuum and studied the ionization of adsorbed hydrogen atoms to H + ions by employing a combined experimental and theoretical approach. Spectroscopic evidence obtained by mass spectrometry and reflection absorption infrared spectroscopy as well as corresponding density functional theory calculations consistently show that adsorbed hydrogen atoms ionize into multiply hydrated proton species (H 5 O 2 + , H 7 O 3 + , and H 9 O 4 + ) on the surface, rather than H 3 O + . Then, upon addition of a water overlayer, the metal‐bound hydrated protons spontaneously evolve into three‐dimensional fully hydrated proton structures through proton transfer along the water overlayer. The stability of hydrated protons on the Pt surface and their bulk dissolution behavior suggest the possibility that surface hydrated protons are a key intermediate in electrochemical interconversion between adsorbed H atoms and H + (aq) in water electrolysis and hydrogen evolution reactions.