New insight into the anomalous codeposition of alloys

A new model for the anomalous codeposition of alloys is based on the kinetic characteristics of metal electrodeposition and th effect of hydrogen evolution accompanying the deposition. The less noble metal has intrinsically faster kinetics and so tis deposition rate can be controlled manly by diffusion mass transfer in a certain range of over potentials; the convection induced by hydrogen evolution can speed up the relative deposition rate of this less noble metal when it is mainly diffusion-influenced. In contrast with previous models, such as the hydroxide suppression hypothesis, the monohydroxide-discharge-controlled mechanism, and the competitive adsorption effect, our model can explain naturally and completely anomalous codeposition, i.e. the preferential deposition of the less-noble metal, oa problem in alloy electrodeposition that has persisted for a century