Metal Deposition by Inducing a Microgalvanic Cell with the Scanning Electrochemical Microscope (SECM)

A new mechanism of metal deposition on conducting surfaces is presented. But in contrast to former procedures where metal ions were deposited by electrolysis on a conducting cathodically polarised surface, now the deposition occurs without any additional electrochemical energy even if the substrate metal is more noble than the deposited metal. This phenomenon can be explained by the formation of a microgalvanic cell as a consequence of the tip reaction. The process is similar to the effects of a local element well known in corrosion science. The latter one is an undesirable effect due to surface impurities whereas the former one can be targeted on generating microstructures. In this paper, we will show that the mechanism of deposition is congenerous to that one of the positive feedback, since both may occur on a nonpolarised conducting surface. Both are “tip-induced” electrochemical cells with a positive electromotive force.