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 WO_4~-2 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.