Electrodeposition of Indium on Glassy Carbon from Tetrabutylammonium Chloride Containing Solutions

Abstract

The effectiveness of tetrabutylammonium chloride (TBACh) as inhibition additive of dendritic growth of indium has been investigated by means of cyclic voltammetry and chronoamperometry methods. The rotating disk electrode (RDE) method allowed the calculation of the diffusion coefficient of In3+ ions using the Levich equation, at 25 °C is 4.41 × 10–6 cm2/s. Diffusion coefficient of indium ions determined by chronoamperometry using the Cottrell law (6.63 × 10–6 cm2/s) is in consistent with the value calculated by the Levich equation. The addition of tetrabutylammonium ions to the electrolyte reduces the diffusion coefficient and inhibits the cathodic process by increasing the activation energy from 10.5 kJ/mol to 20.7 kJ/mol. The indium nucleation and growth on glassy carbon in chloride solutions was studied by single potentiostatic pulse techniques. The nucleation mechanism was evaluated by analyzing the influence of different TBACh ion concentration and applied potentials. The electrocrystallization mechanisms were determined by fitting the experimental non-dimensional current transients on the basis nucleation and growth model developed by Scharifker-Hills. The type of nucleation corresponding to the progressive three-dimensional nucleation with diffusion control is determined. Based on theoretical models of 3D multiple nucleation from the potentiostatic current transients were calculated nucleation characteristics, such as the stationary nucleation rate, saturation nucleus density and the average grains radius of indium deposits. The leveling action of TBACh on the electrodeposition of indium at concentration of 10-4 M was found.