A New Approach to the High Resolution Electrodeposition of Metals via the Feedback Mode of the Scanning Electrochemical Microscope

Gold and palladium electrodeposition in polymer films immersed in solution with high resolution has been accomplished using the scanning electrochemical microscope (SECM). The SECM was used in the feedback mode, where hexaamminoruthenium(III), Ru(NH₃)₆³⁺, was reduced at an ultramicroelectrode (UME) and diffused to a protonated polyvinyl pyridine-coated surface. When metal anions, e.g., AuCl₄^- or PdCl₄², were incorporated in the polymeric matrix, the diffusion of reduced mediator, Ru(NH₃)²⁺, from the UME to the polymer film resulted in metal deposition. The different factors that determine the size and pattern of deposited metal were examined. The difference between gold and palladium deposition was studied by several techniques and interpreted in terms of kinetic and thermodynamic properties of the mediator and the metal complex.