Kinetic analysis of electrosorption using fast Fourier transform electrochemical impedance spectroscopy:: underpotential deposition of Bi3+ in the presence of coadsorbing ClO4- on gold

We demonstrate a relatively simple method for studying various kinetic aspects of metal electrodeposition in the presence of coadsorbing anions on an electrode surface. This method combines cyclic voltammetry (CV) with fast Fourier transform electrochemical impedance spectroscopy (FFT-EIS), where both steady state and transient behaviors of the interface are probed simultaneously. As a model surface reaction, we use electrodeposition of Bi3+ in the presence of ClO4- adsorption from an aqueous solution onto a gold electrode. The voltage range for underpotential deposition (UPD) of Bi3+ is determined with potential step (PS) experiments. The voltage dependent UPD coverage of Bi on Au is determined by analyzing the CV data. The relevant kinetic parameters of both Bi3+ and ClO4- deposition reactions under the conditions of CV are measured with FFT-EIS, and analyzed using a complex nonlinear least square method. The differences and similarities between the electrosorption characteristics of Bi3+ and ClO4- on Au are discussed in terms of these kinetic parameters. (C) 2002 Elsevier Science Ltd. All rights reserved.