Model for nickel-iron alloy electrodeposition on a rotating disk electrode

A model for Ni-Fe alloy electrodeposition from a sulfate bath onto a rotating disk electrode was developed. The model is based on an alternate description of electrode kinetics. The model assumed Ni exp 2+ and Fe exp 2+ as the electroactive species and that NiOH exp + and FeOH exp + are not involved. Transport of each dissolved species was assumed to occur via diffusion, convection, and migration. Comparison of simulations with experimental data showed that the model can predict characteristic features of the nickel-iron system such as anomalous codeposition and occurrence of a maximum in iron content in the deposit at intermediate currents. The computed changes in surface pH agreed well with experimental near-surface pH measurement data reported in literature but were too low for NiOH exp + and FeOH exp + to be present in sufficient amounts.