Electrochemical and electrophoretic deposition of materials obtained by anodic dissolution of metals in water

Electrochemical dissolution of metal anodes in unsupported medium such as water generates metal oxide/hydroxide material which can be deposited onto a suitable substrate connected as a cathode in the electrochemical cell. Depending on the properties of anode-derived material (zeta potential and solubility), metal electroreduction or electrophoretic deposition of anode-derived material can be achieved. Nanostructured deposits can be applied as amperometric and SERS sensors. In the previous works1-3, we showed that anodization of silver and copper in ultrapure water leads to Ag+ resp. Cu2+ cations, reacting with OH- ions available from the autoprotolysis of water to give corresponding hydroxides, eventually transformed by further hydrolytic reactions. This anode-derived material is transported in the interelectrode space by electrophoretic, diffusion and convection induced by density or temperature gradients. After reaching the surface of the counterelectrode (cathode), a deposit is formed. Recently, the above described strategy was used also to deposit nickel and copper-copper nickel alloy onto carbon fiber microelectrodes. In the case of silver and copper the procedure leads to elemental silver resp. copper while material obtained from nickel and copper-nickel alloy is of oxidic nature, as suggested by EDX.