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Alternating Current Measurements in Scanning Electrochemical Microscopy, Part 2: Detection of Adsorbates
Author(s) -
Trinh Dao,
Keddam Michel,
Novoa Xosé Ramón,
Vivier Vincent
Publication year - 2011
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.201001085
Subject(s) - scanning electrochemical microscopy , nyquist plot , adsorption , analytical chemistry (journal) , chemistry , electrochemistry , sulfuric acid , dielectric spectroscopy , capacitance , hydrogen , relaxation (psychology) , scanning probe microscopy , materials science , inorganic chemistry , electrode , nanotechnology , chromatography , organic chemistry , social psychology , psychology
A scanning electrochemical microscope (SECM) in ac mode is used for the characterisation of the adsorption process during the hydrogen evolution reaction (HER) in sulfuric acid solution. It is shown that this technique allows quantitative analysis of the adsorption process, and measurements of the differential capacitance with the frequency as parameter are obtained. The time constant for relaxation of adsorbed hydrogen (H ads ) is approximately 2 Hz, and analysis of the Nyquist plot allows direct evaluation of the charge involved. In addition, the direct comparison of the usual electrochemical impedance data and ac‐SECM results obtained simultaneously permits characterisation of processes occurring at the surface and in solution.