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In Situ Video‐STM Studies of Adsorbate Dynamics at Electrochemical Interfaces
Author(s) -
Tansel Tunay,
Taranovskyy Andriy,
Magnussen Olaf M.
Publication year - 2010
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200900939
Subject(s) - chemical physics , chemistry , diffusion , scanning tunneling microscope , electrochemistry , metastability , surface diffusion , sulfur , lattice (music) , adsorption , quantum tunnelling , in situ , electrode , analytical chemistry (journal) , materials science , nanotechnology , thermodynamics , physics , optoelectronics , organic chemistry , chromatography , acoustics
The dynamic behavior of individual adsorbates at electrochemical interfaces was studied directly by in situ high‐speed scanning tunneling microscopy, using sulfur adsorbed on Cu(100) electrodes in 0.01 M HCl solution as an example. By dosing from diluted Na 2 S solutions S ad coverages of a few percent can be prepared, with the sulfur adsorbates occupying positions within the c (2×2) lattice of coadsorbed chloride. S ad tracer diffusion occurs via hopping between neighboring c (2×2) lattice sites at considerably higher rates than those of sulfur on Cu(100) under UHV conditions, indicating a pronounced influence of the electrochemical environment on the adsorbate surface dynamics. The diffusion barrier linearly increases by 0.5 eV per V with potential and is strongly affected by neighboring S ad and surface defects. The S ad S ad interactions extend over ≈7 Å. They are repulsive between nearest‐neighbor and attractive between next‐nearest‐neighbor sites, respectively, and result in significantly reduced diffusion barriers. S ad on the upper terrace side of steps are transiently trapped and exhibit lower diffusion rates, leading to the formation of small metastable p (2×2) domains. Attractive interactions between S ad and domain boundaries in the c (2×2) adlayer result in boundary pinning as well as transient trapping and enhanced diffusion of S ad along the boundary.