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Room Temperature CO ad Desorption/Exchange Kinetics on Pt Electrodes—A Combined In Situ IR and Mass Spectrometry Study
Author(s) -
Heinen Martin,
Chen YanXia,
Jusys Zeas,
Behm Rolf Jürgen
Publication year - 2007
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.200700425
Subject(s) - chemistry , desorption , electrolyte , analytical chemistry (journal) , mass spectrometry , kinetics , adsorption , partial pressure , electrode , inorganic chemistry , chromatography , organic chemistry , physics , quantum mechanics , oxygen
The room temperature desorption and exchange of CO in a saturated CO adlayer on a Pt electrode, at potentials far below the onset of oxidation, was investigated by isotope labeling experiments, using a novel spectroelectrochemical setup, which allows the simultaneous detection of adsorbed species by in situ IR spectroscopy and of volatile (side) products and reactants by online mass spectrometry under controlled electrolyte flow conditions. Time‐resolved IR spectra show a rapid, statistical exchange of pre‐adsorbed 13 CO ad by 12 CO ad in 12 CO containing electrolyte; mass spectrometric data reveal first‐order exchange kinetics, with the rate increasing with CO partial pressure. The increasing CO ad desorption rate in equilibrium with a CO containing electrolyte is explained by a combination of an increasing CO ad coverage upon increasing the CO pressure, and a decrease of the CO adsorption energy with coverage, due to repulsive CO ad –CO ad interactions.