Electrodeposition of Binary Iron‐Group Alloys

Thin films of and have been galvanostatically electroplated onto a platinum rotating disk electrode from simple sulfate baths containing 0.5 M of the more noble metal sulfate and 0.1 M of the less noble metal sulfate. The experimental results are compared to those of previous studies of codeposition in order to study the anomalous codeposition behavior of the binary iron‐group alloys. Comparison of the electrodeposition results indicates that codeposition of these binary alloys is not totally analogous. It was found that codepositions of and show more mass‐transfer effects than does deposition within the range of current densities studied. A model of anomalous codeposition put forth previously for was applied to the electrodeposition of and to determine the extensibility of the model, which assumes metal monohydroxides, , are the important charge‐transfer species. This model was unable to characterize fully either or electrodeposition. However, with minor changes to the hydrolysis constants used in the model, the model predictions were found to agree with the data for codeposition and greatly improve the fit for the results.