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The Nature of Hydrogen Adsorption on Platinum in the Aqueous Phase
Author(s) -
Yang Guoju,
Akhade Sneha A.,
Chen Xi,
Liu Yue,
Lee MalSoon,
Glezakou VassilikiAlexandra,
Rousseau Roger,
Lercher Johannes A.
Publication year - 2019
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201813958
Subject(s) - adsorption , hydronium , chemistry , aqueous solution , hydrogen bond , platinum , hydrogen , standard molar entropy , ion , platinum nanoparticles , inorganic chemistry , molecule , standard enthalpy of formation , catalysis , organic chemistry
The thermodynamic state of H 2 adsorbed on Pt in the aqueous phase was determined by kinetic analysis of H 2 reacting with D 2 O to HDO, HD, and D 2 , and by DFT‐based ab initio molecular dynamics simulations of H 2 adsorption on Pt(111), Pt(110), and Pt nanoparticles. Dissociative adsorption of H 2 on Pt is significantly weakened in the aqueous phase compared to adsorption at gas–solid interfaces. Water destabilizes the adsorbed H atoms, decreasing the heat of adsorption by 19–22 kJ m o l H 2- 1while inducing an additional entropy loss of 50–70 J m o l H 2- 1 K −1 . Upon dissociative adsorption of H 2 , the average distance of water from the Pt surface increases and the liquid adopts a structure that is more ordered than before close to the Pt surface, which limits the translation mobility of the adsorbed H atoms. The presence of hydrated hydronium ions next to the Pt surface further lowers the H−Pt bond strength.