Open-Circuit Deposition of Ultra-Thin Metallic Layers: Surface Limited Reactions under Potential Control

FONTICELLI, M. H.; CORTHEY, G.; SALVAREZZA, R. C.

Manchester

Congreso; Electrochem09; 2009

The growth of Ultra-Thin metal layers has always been a major goal of electrodeposition. Although electroless deposition has demonstrated to be a powerful tool in this matter, these processes are carried out under conditions which are not precisely controlled. On the other hand, the interfacial potential and the deposited amount are magnitudes that should be controlled in order to growth structures in the nanometer range. Underpotential deposition (UPD) is a phenomenon where an atomic layer of a less noble element is deposited on a second, more noble, element, which is a prominent example of an electrochemical surface limited reaction. This strategy, by itself or combined with surface limited redox replacement reactions, allows the formation of a wide variety of homo and heterometallic deposits in very precisely and controlled ways. However, its application requires fixing the potential, in order to regulate the deposited element coverage. Here, a novel synthesis route for Ultra-Thin adlayers preparation is presented. This method consists in the use of a redox couple to control the interfacial potential, fixing it in the UPD range. It allows the deposition of extremely small amounts of metals under equilibrium conditions, both on planar extended and nanoparticles surfaces. Furthermore, thiolate-covered metal surfaces can be modified with adatoms. It is interesting to note that, while bulk deposition generally buries the underlying self-assembled monolayer, in this case the metal protected clusters are still protected. These results make this novel strategy an alternative to produce bimetallic systems.