Regensburg 2022 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 38: Solid-Liquid Interfaces 4: Reactions and Electrochemistry
O 38.4: Vortrag
Mittwoch, 7. September 2022, 11:30–11:45, H4
Measuring the reaction volume of an electrochemical surface process: Cu underpotential deposition on Au(111) — •Lisa Hirsch, Bianca Krumm, Tamara Meyer, and Rolf Schuster — Karlsruhe Institute of Technology
Information about the reaction volume of electrochemical surface reactions is rather scarce [1-3] albeit this thermodynamic quantity would allow conclusions on solvent contribution and possible side processes. With a specifically designed electrochemical cell, we determined the variation of the cell potential of a (111)-textured Au-film in CuSO4 / H2SO4 vs a Cu reference electrode, while applying pressure pulses of moderate amplitude (< 10 bar) and durations of several seconds, starting at different rest potentials. According to the pressure dependend potential variation, we calculated the reaction volume ΔRV of the processes at the working electrode. For rest potentials in the Cu UPD region, ΔRV varies only slightly (± 8 cm3/mol) around ΔRV=18cm3/mol, its value for Cu bulk deposition, moderately peaking upon formation of the (√3×√3) Cu UPD structure. Positive of the Cu UPD, in the sulfate adsorption region, ΔRV drops to smaller values. We check the integrity of the measured potential variations by their dependence on the pressure amplitude as well as by measuring the symmetrical Cu|Cu2+,SO42−|Cu cells.
[1] Conway, B. E., Currie, J. C., J. Chem. Soc., 74, 1978, 1390-1402. [2] Loewe, T., Baltruschat, H., Phys. Chem. Chem. Phys., 7, 2005, 379-384. [3] Heusler, K. E., Gaiser, L., Ber. Bunsenges. Phys. Chem., 73, 1969, 1059-1068.