Electrochemical Investigation of Bi-Fe Alloy Thin Films Prepared by Electrodeposition

The electrodeposition of Bi, Fe, and Fe-Bi alloy from an acetate solution at pH 6.50 on a glassy carbon electrode at ambient temperature was studied using cyclic voltammetry, chronoamperometry, and scanning electron microscopy (SEM). The solutions prepared for alloy coating deposition consisted of CH 3 COOH, Bi 5 H 9 N 4 O 22 , FeSO 4 ·7H 2 O, (NH 4 ) 2 SO 4 , Na 3 C 6 H 5 O 7 ·2H 2 O, H 3 BO 3 , and NH 4 OH. The results showed that the simultaneous deposition of Fe and Bi was facilitated by the complexing action of Na 3 C 6 H 6 O 7 and NH 4 OH, effectively reducing the difference in the reduction potentials of the two metals. Cyclic voltammetry results indicate that the deposition processes are diffusion-controlled, with diffusion coefficients for Bi 3+ and Fe 2+ calculated as 1.17 × 10 –4 and 4.97 × 10 –7 cm 2 s −1 , respectively. Based on dimensionless curves and the Scharifker and Hills theory, the nucleation mechanism analysis revealed that Fe 2+ undergoes progressive nucleation, while Bi 3+ and the Bi 3+ -Fe 2+ system transition from instantaneous to progressive nucleation. Surface morphological analysis by SEM of Bi, Fe, and Fe–Bi electrodeposits, performed at 10 and 60 s intervals, further corroborates the conclusions derived from dimensionless plots and the Scharifker and Hills theory. These findings provide valuable insights into these electrochemical systems’ nucleation and growth behavior.