Kinetics of hydrogen evolution on copper electrode in acetic and gluconic acid solutions

Abstract

Linear potential sweep (LPS) voltammetry was applied to study the kinetics of hydrogen evolution on the copper electrode in the systems containing acetic or gluconic acid as proton donors. To determine the kinetic parameters, different methods of analysis were used: convolution of experimental voltammograms with the following construction of normalized Tafel plots, as well as analysis of the voltammetric extremes (peak current and potential). The effective exchange current density of the same order (~1 nA cm–2) was obtained for both systems. The effective diffusion coefficients (D), determined for the acetate system by convolution procedures, are in good agreement with literature data, whereas 2 times reduced D values follow from a similar analysis applied to the gluconate system. In the latter case, considerable variations in the values of the charge transfer coefficient are also observed. The reason for insufficient reliability of parameters determined for the gluconate system is its unsufficient lability, which requires taking into account the kinetics of chemical steps of the total electrochemical process.