Exploring the determination of the standard rate constant in electrochemical metal deposition: theory and experiment

A detailed investigation of the electrochemical metal deposition was carried out using both simulation and experimental cyclic voltammetry (CV). Kinetic curves were developed to relate peak-to-peak potential separation (Δ<i>E</i> _p) to the cathodic charge transfer coefficient (<i>α</i>) and the standard rate constant (<i>k</i> ⁰). From these curves, interpolation equations were derived to estimate <i>k</i> ⁰, taking into account the effect of the transfer coefficients sum (<i>α</i> + <i>β</i>), whether equals to or different from 1. The validity of the equations was confirmed through the reduction of silver, copper and rhenium ions in various electrolytes, yielding <i>k</i> ⁰ values of 14.51 × 10^-6 m s^-1 for Ag⁺/Ag, 5.98 × 10^-7 m s^-1 for Cu⁺/Cu and 10.59 × 10^-8 m s^-1 for Re⁶⁺/Re. According to the Matsuda-Ayabe criteria for assessing electron-transfer reversibility, the Ag⁺/Ag and Cu⁺/Cu redox couples are regarded as quasi-reversible, while the Re⁶⁺/Re couple is classified as irreversible. The simulated CVs showed strong agreement with experimental results.