The influence of frequency on fractal dimension of adsorbed layers

Abstract

Ac voltammetry and electrochemical impedance spectroscopy are often the methods of choice for use in study of adsorption of organic molecules. The adsorption of organic molecules on interface may results in formation of fractal structures, whose fractal dimension can be estimated using the method of scaling the hanging mercury drop electrode (HMDE). The aim of present study was to check whether the estimated fractal dimension, D (or for that matter the fractal ordering of the adsorbed layer)shows any correlation (dependence) with change of applied frequency, and second, to check the possibility to extend the method to broad frequency spectrum compatible with impedance spectroscopy. The investigation included two surfactants nonionic Triton-X-100 (T-X-100) and anionic sodium dodecyl sulfate (SDS) and alcohol tertbutanol. All measurements were performed on HMDE at thermodynamic equilibrium employing broad frequency spectrum. The validity of the approach was checked by measurements on pure electrolyte and by comparison with previously obtained results for fractal layers. The results of the investigations show that: (1) the method of scaling the HMDE to obtain the fractal dimension of adsorbed layer is compatible with impedance spectroscopy and the combination of these methods can be used as a powerful tool to investigate fractal aspect of adsorption of organic molecules; (2) fractal ordering of adsorbed layer and the value of fractal dimension is not influenced by the frequency of applied sinusoidal voltage perturbations.

Square‐Wave Voltammetry of Electroinactive Surfactants

“…Similar effects, i.e. the dependence of AC experimental results on the reactant concentration were previously observed by other authors 29 and ascribed to different types of molecular associations. In order to avoid the mentioned “complications”, all other measurements were performed at c (SDS)≤2×10 −5 mol/L.…”

Electrochemical Noise Chaotic Analysis of NiCoAg Alloy in Hank Solution

“…Generally, if the D fs value falls around 2.0, this indicates that the metal surface is smooth and homogeneous; otherwise, if the value is lower than 3.0, it is because the metal surface is heterogeneous and rugged. Gasparovic et al [45] explained the surface of an electrode by using the fractal geometry [33]. It has been demonstrated that the fractal dimension of an electrode can be determined by means of electrochemical impedance measurements and correlated with atomic force microscopy [35].…”

A combined electrochemical and theoretical study of N,N′-bis(benzimidazole-2yl-ethyl)-1,2-diaminoethane as a new corrosion inhibitor for carbon steel surface

“…Gasparovic [49] explained the surface of electrode by using the fractal geometry of the electrode, thus we used this technique as a powerful tool to study the organic molecule adsorption over the metal surface.…”