Electrode resistance in the electrochemical cell; analysis of size effect theory with the specific adsorption of Br − and I − on polycrystalline gold films

• Published in: Surface science 1984, Vol.136 (1), p.195-216
• Main Authors: Rath, David L., Hansen, Wilford N.
• Format: Article
• Language: English
• Subjects: Analysing. Testing. Standards; Applied sciences; Chemistry; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; General and physical chemistry; Materials science; Measurement of properties and materials state; Metals, semimetals and alloys; Metals. Metallurgy; Nondestructive testing; Physics; Solid-liquid interface; Specific materials; Surface physical chemistry
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/0039-6028(84)90665-4

The effects of specific adsorption on the in situ resistance measurement are studied using polycrystalline gold film electrodes of various thicknesses. A differential technique is developed where the instantaneous changes in the electrode resistance are correlated to the voltammetric current in linear sweep voltammetry. With the successful separation of the interfacial processes on these measurements, it is shown that the electrode resistance has a linear response to the coverage of the specifically adsorbed Br − and I − ions, independent of the electrochemical parameters. While the sensitivity of the resistance to adsorption depends strongly on the intrinsic properties of the gold film, it is shown that the ratio of the resistance responses to these halides on the same electrode is invariant. In the framework of the scattering hypothesis of Wedler and Wissman, the apparent scattering cross section of iodide on gold is approximately 0.015 nm 2 as determined by an extrapolation of the resistance response to infinite thickness. With the electrosorption valency of bromide as −0.81, the corresponding apparent scattering cross section is accurately determined to be 0.66 times that for iodide.