Oxygen Incorporation during the Electrodeposition of Ni, Fe, and Ni‐Fe Alloys

This study sought to quantify the oxygen content of electrodeposited Ni, Fe, and Ni‐Fe alloys and to identify mechanisms by which the oxygen is incorporated in the deposits. In the absence of boric acid in the bath, the oxygen content of electrodeposited Ni increases with increasing applied current density. This behavior corresponds to a significant increase in the pH of the solution adjacent to the cathode, which results in the precipitation of on the cathode and occlusion of this material in the growing deposit. The incorporation of oxygen during Ni‐Fe electrodeposition is similar, except that an increase in the concentration in the bath reduces the oxygen content. This behavior results from buffering provided by that accompanies the in this system. When boric acid is present in the bath, oxygen incorporation is low in all three electrodeposition systems. This observation is consistent with buffering of the cathode pH resulting from boric acid's ability to complex with , which generates as a by‐product. The oxygen that is incorporated may be attributed to hydroxide ion that fails to leave the surface following its participation in the electroreduction process. In Ni‐Fe electrodeposition, oxygen incorporation by particle codeposition is shown to play an insignificant role.