Zundel- and Eigen-like Surface Hydrated Protons on Pt(111)

  • Kim, Youngsoon (Department of Chemistry, Seoul National University) ;
  • Park, Youngwook (Department of Chemistry, Seoul National University) ;
  • Shin, Sunghwan (Department of Chemistry, Seoul National University) ;
  • Kang, Heon (Department of Chemistry, Seoul National University)
  • Published : 2016.02.17

Abstract

The interaction between adsorbed water and hydrogen on metallic surfaces is important for fundamental understanding of heterogeneous catalysis and electrode surface reactions in acidic environment. Here, we explore a long-standing question of whether hydronium ion can exist or not on a Pt surface coadsorbed with atomic hydrogen and water. Studies based on mass spectrometry and infrared spectroscopy show clear evidence that hydrogen atoms are converted into hydrated protons on a Pt(111) surface. The preferential structures of hydrated protons are identified as multiply hydrated $H_5O_2{^+}$ and $H_7O_3{^+}$ species rather than as hydronium ions. The multiply hydrated protons may be regarded as two dimensional zundel ($H_5O_2{^+}$) and Eigen cation ($H_7O_3{^+}$) in water-metal interface. These surface-bound hydrated protons may be key surface intermediates of the electrochemical interconversion between adsorbed hydrogen atoms and solvated protons.

Keywords