A Study of <scp>N</scp>ickel <scp>E</scp>lectrodeposition on <scp>P</scp>araffin‐<scp>I</scp>mpregnated <scp>G</scp>raphite <scp>E</scp>lectrode

Abstract

Abstract The aim of the present work was to elucidate the mechanism of electrolytic deposition of Ni on paraffin‐impregnated graphite electrode (PIGE). This process is influenced by H 2 evolution, which occurs in the same potential region. On the basis of the results obtained by linear and cyclic voltammetry, elimination voltammetry with linear scan (EVLS) was used to evaluate both processes. H 2 Evolution alone was studied in sulfate supporting electrolyte, and the previously suggested mechanism for this process according to Volmer–Heyrovsky was confirmed by EVLS. It was found that both the Ni 2+ concentration and pH affect the polarization behavior of PIGE significantly. Two separated cathodic peaks were observed at low Ni 2+ and high H + concentrations, and the separation was better at higher scan rates. EVLS confirmed the most‐probable mechanism of Ni deposition as being controlled by slow transfer of the first electron under formation of [NiOH] + as an intermediate. EVLS also indicated slow reduction of H + preceding the reduction of Ni 2+ . The same was confirmed by studying the anodic dissolution at different switching potentials. The results were complemented by scanning electron microscopy (SEM).