Kinetics of Ni-W Alloy Electro-deposition in Acidic Sulphate Electrolyte

Cyclic voltammetry curves (CV) and chronoamperometry(CA) in conjunction with the Scharifker-Hills model (SH) were used to study the initial stage of Ni-W alloy electro-deposition. The results indicated that the electro-deposition of the Ni-W alloy on glassy carbon electrode consisted of nucleation and growth. The crystal nucleation of plating improved as the concentration of WO42- increased and its reduction intermediate products could be considered as favorable sites of the Ni-W alloy. According to the analysis of Scharifker-Hills model, the pure Ni nucleation process follows a three dimension-instantaneous mechanism, while the Ni-W alloy is a progressive nucleation mechanism at a lower over-potential, which slightly deviats from the progressive nucleation curve at higher over-potential and shows a instantaneous nucleation mechanism.