关键词: 电结晶, 铋, 玻碳电极, 成核, 生长, Scharifker公式, Heerman公式

Abstract: The electrocrystallization of bismuth on glassy carbon electrodes (GCEs) from nitrate solutions was studied by cyclic voltammetry and chronoamperometry. Cyclic voltammograms exhibit a crossover between the cathodic and anodic branches, characteristic of the formation of bismuth nuclei on GCEs, and show that the bismuth electrocrystallization on GCEs is a diffusion-controlled reaction. The current transients were analyzed with the Scharifker and the Heerman equations. With the increaseof Bi~(3+)concentration, the non-dimensional plots leaned to the theoretical curve for 3D instantaneous nucleation and growth. The overpotential dependence of nucleation and growth mechanism was also found. With the increase of overpotential, the non-dimensional curve approaches closer the limit for 3D instantaneous nucleation and growth. A quantitative analysis further shows that the nucleation rate constant (A) and the number density of active sites (N_(0 )) exponentially grow with the increase of overpotential, and the diffusion coefficient (D)decays in an exponential mode, which was not reported before. A comparison between the kinetic parameter values obtained from the Scharifker equation and those from the Heerman equation was made, showing the very close N_0 and Dvalues and the distinct Avalues (especially at -300 and -350 mV). However, under the experimental conditions of this work, both of the equations can be used for describing the electrocrystallization of bismuth on GCEs.

Key words: Electrocrystallization, Bismuth, Glassy carbon electrode, Nucleation, Growth, Scharifker (equation), Heerman equation