title: Identification of Non-Faradaic Processes by Measurement of the Electrochemical Peltier Heat during the Silver Underpotential Deposition on Au(111).
abstract: 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.
authors.affiliation: Institut für Physikalische Chemie, Karlsruhe Institute of Technology, Kaiserstrasse 12, 76131 Karlsruhe, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Frittmann
authors.affiliation: Institut für Physikalische Chemie, Karlsruhe Institute of Technology, Kaiserstrasse 12, 76131 Karlsruhe, Germany.
authors.forename: Vadym
authors.initials: V
authors.lastname: Halka
authors.affiliation: Institut für Physikalische Chemie, Karlsruhe Institute of Technology, Kaiserstrasse 12, 76131 Karlsruhe, Germany. rolf.schuster@kit.edu.
authors.forename: Rolf
authors.identifier: http://orcid.org/0000-0003-3136-6403
authors.initials: R
authors.lastname: Schuster
keywords: Peltier heat; calorimetry; electrochemistry; electrodeposition; reaction entropy