Electrochemical Pd deposition onto Rh(1 1 1): from cluster to monolayer growth

The electrochemical deposition of Pd onto Rh(1 1 1) from PdCl2 containing solution was investigated by means of STM and cyclic voltammetry. By decreasing the overpotential, a transition from three-dimensional cluster growth to monolayer formation was found. Deposition of Pd slightly above the Nernst potential leads to formation of a flat monolayer. Detailed structural information about the different Pd morphologies has been obtained from STM data. The electrochemical behaviour of the first Pd layer on Rh(1 1 1) is distinctly different from that of bulk Pd, whereas for the second layer onward Pd bulk properties are found.