Analysis of the initial stages of electrocrystallization of Fe, Co and Fe-Co alloys in chloride solutions

the electrodeposition of fe, co and fe-co alloys onto pt has been investigated from chloride solutions at ph 2.0. the fe-co alloys were deposited from solutions with molar ratio of 1:10, 1:1 and 10:1. electrocrystallization of metals was studied by potentiostatic steps. the scharifker and hills model was used to analyze current transients. a progressive nucleation mechanism was found to fit the experimental results for both co and fe-co alloys deposited from 1:10 solution. in the case of pure fe and fe-co alloy, deposited from 1:1 and 10:1 solutions, the nucleation process occurred by the instantaneous mechanism. the nuclei number densities and rate of nucleation were calculated and their values were 2.6 to 19.1 x 103 cm-2 for fe and 0.10 to 15.8 x 106 cm-2 s-1 for co deposition.