Open AccessCO Adsorption and Disproportionation on Smooth and Defect-Rich Ir(111)
Author(s) -
Xia Li,
Thomas Haunold,
Stefan Werkovits,
Laurence D. Marks,
Peter Blaha,
Günther Rupprechter
Publication year - 2022
Publication title -
journal of physical chemistry. c./journal of physical chemistry. c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.401
H-Index - 289
eISSN - 1932-7455
pISSN - 1932-7447
DOI - 10.1021/acs.jpcc.2c01141
Subject(s) - disproportionation , x ray photoelectron spectroscopy , auger electron spectroscopy , adsorption , density functional theory , dissociation (chemistry) , low energy electron diffraction , chemistry , analytical chemistry (journal) , electron diffraction , spectroscopy , infrared spectroscopy , diffraction , materials science , nuclear magnetic resonance , computational chemistry , optics , biochemistry , physics , organic chemistry , chromatography , quantum mechanics , nuclear physics , catalysis
CO adsorption and dissociation on "perfect" and "defect-rich" Ir(111) surfaces were studied by a combination of surface-analytical techniques, including polarization-dependent (PPP and SSP) sum frequency generation (SFG) vibrational spectroscopy, low-energy electron diffraction (LEED), Auger electron spectroscopy, X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations. CO was found to be ordered and tilted from the surface normal at high coverage on the "perfect" surface (e.g., θ = 30° at 0.70 ML), whereas it was less ordered and preferentially upright (θ = 4-10°) on the "defect-rich" surface for coverages of 0.55-0.70 ML. SFG, LEED, and XPS revealed that CO adsorption at low pressure/high temperature and high pressure/low temperature was reversible. In contrast, upon heating to ∼600 K in near mbar CO pressure, "perfect" and even more "defect-rich" Ir(111) surfaces were irreversibly modified by carbon deposits, which, according to DFT, result from CO disproportionation.