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Identification of Non‐Faradaic Processes by Measurement of the Electrochemical Peltier Heat during the Silver Underpotential Deposition on Au(111)
Author(s) -
Frittmann Stefan,
Halka Vadym,
Schuster Rolf
Publication year - 2016
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201600337
Subject(s) - underpotential deposition , electrochemistry , chemistry , cyclic voltammetry , inorganic chemistry , standard molar entropy , thermoelectric effect , hydroxide , deposition (geology) , electrochemical potential , adsorption , analytical chemistry (journal) , standard enthalpy of formation , electrode , thermodynamics , organic chemistry , physics , sediment , biology , paleontology
We measured the heat which is reversibly exchanged during the course of an electrochemical surface reaction, i.e., the deposition/dissolution of the first two monolayers of Ag on a Au(111) surface in (bi)sulfate and perchlorate containing electrolytes. The reversibly exchanged heat corresponds to the Peltier heat of the reaction and is linearly related to its entropy change, including also non‐Faradaic side processes. Hence, the measurement of the Peltier heat provides thermodynamic information on the electrochemical processes which is complementary to the current–potential relations usually obtained by conventional electrochemical methods. From the variation of the molar Peltier heat during the various stages of the deposition reaction we inferred that co‐adsorption processes of anions and Ag do not play a prominent role, while we find strong indications for a charge neutral substitution reaction of adsorbed anions by hydroxide, which would not show up in cyclic voltammetry.