Influence of tetrabutylammonium chloride on the electrodeposition of indium from chloride solution on a glassy carbon electrode

Abstract

In this paper, the electrochemical reduction of indium on a glassy carbon electrode (GCE) in a chloride electrolyte in the presence of tetrabutylammonium chloride (TBACh) was studied using the rotating disk electrode method, chronoamperometry and scanning electron microscopy. It was found that the addition of TBACh inhibits the electroreduction of indium by increasing the activation energy of the process by 17 kJ mol−1, and also shows leveling action at its low concentrations. The diffusion coefficient of indium (III) ions found from Levich equation at 25 °C, was 4.93 × 10−6 cm2 s−1. The In3+ diffusion coefficient determined using the Levich equation are consistent with the values determined by the Cottrell law and universal Stokes-Einstein equation. The addition of 10−4 M TBACh to the electrolyte reduces the diffusion coefficient to 2.13 × 10−6 cm2 s−1. The type of crystallization corresponding to the progressive 3D nucleation with diffusion control has been established. Using the Scharifker-Hills, Scharifker-Mostany and Mirkin-Nilov-Heerman-Tarallo models nucleation parameters were calculated, which correlate well with the results of scanning electron microscopy. Addition of TBACh increases the nucleation rate at −0.90 V from 9.19 × 106 cm−2 s−1 to 48.09 × 106 cm−2 s−1 and reduces the average radius of grains of indium coatings from 18.0 μm to 6.8 μm.