Structure Revealing H/D Exchange with Co-Adsorbed Hydrogen and Water on Gold.
A fundamental understanding of the interactions between coadsorbed water and hydrogen on metallic surfaces is critical to many chemical processes including catalysis and electrochemistry. Here, we report on the strong and intricate interactions between coadsorbed H/D and water on the close-packed (111) surface of gold. Deuterium isotopic labeling shows H/D exchange in H-D2O and D-H2O systems, indicating water dissociation and suggesting a nonrandom scrambling process by revealing the origin of hydrogen evolution (from surface H atoms or from water molecules) during annealing. In this reaction, the protonation of the H-bonding ice network (i.e., the formation of (H2O)nH(+)) is energetically favorable and is responsible for water dissociation. Density functional theory (DFT) modeling suggests that the thermodynamics and structure of the protonated clusters are predominant factors for yielding the traceable H2 desorption features from the surface interaction with H atoms, providing insights into reaction mechanisms.
Departments of Chemical Engineering and Chemistry and Biochemistry, Center for Electrochemistry, and Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, Texas 78712-0231, United States.
Ming
M
Pan
Departments of Chemical Engineering and Chemistry and Biochemistry, Center for Electrochemistry, and Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, Texas 78712-0231, United States.
Zachary D
ZD
Pozun
Departments of Chemical Engineering and Chemistry and Biochemistry, Center for Electrochemistry, and Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, Texas 78712-0231, United States.
Wen-Yueh
WY
Yu
Departments of Chemical Engineering and Chemistry and Biochemistry, Center for Electrochemistry, and Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, Texas 78712-0231, United States.
Graeme
G
Henkelman
Departments of Chemical Engineering and Chemistry and Biochemistry, Center for Electrochemistry, and Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, Texas 78712-0231, United States.
C Buddie
CB
Mullins
density functional theory; gold catalysis; gold surface chemistry; interaction of water and hydrogen; isotope effect; protonated water clusters; temperature-programmed desorption